Embed Size (px)
Citation preview
SECTION 4_MATERIALS
4.1 General
4.1.1 Miscellaneous informat¡on is conta¡ned ¡n 4.1.1.1 through 4.1.1.4.
4.1.'1.1 See the Data Sheet for material specifications.
4.1.1.2 R¡mmed or capped steels are not perm¡tted.
4.1.1.3 Use of cast iron for any pressure part or any part attached to the tank by welding is prohibited.
4.1.1.4 Because of hydrogen embrittlement and toxicity concerns, cadmium-plated components shall not be usedwithout the expressed consent of the Purchaser.
¿1.1.2 Materials used in the construct¡on of tanks shall conform to the specif¡caüons listed ¡n th¡s section, subject tothe modificaüons and limitations indicated in this standard. Material produced to specifications other than those listedin th¡s sect¡on may be employed, prov¡ded that the mater¡al is cenif¡ed to meet all of the requirements of an applicablemater¡al specilicat¡on l¡sted in th¡s standard and the material's use ¡s approved by the Purchaser. The Manufacturer'sproposal shall ¡dentify üe material spec¡fications to be used. When this standard does not address rnaterialrequirements for miscellaneous items and appurtenarrces, the Purchaser and/or the Manufacturer shall supplyaddit¡onal riaterial requirements using a supplement to the Data Sheet.
4.1.3 When any new or unused plate and pipe material cannot be completely ident¡f¡ed by records that aresaüsfactory to the Purchaser as material conforming to a specificaüon listed ¡n th¡s standard. the material or productmay be used in the construcüon of tanks covered by this standard only if the material passes the tests prescribed ¡n
Annex N.
4.1.4 Where mater¡als of construcüon are used that are certif¡ed to two or more rnaterial specificaüons, the mater¡alspecif¡cation chosen for the des¡gn calculaüons shall also be used cons¡stently in the applicaüon of all otherprovisions of this standard. The Purchaser shall be notjfied of th¡s cho¡ce and rece¡ve conf¡rmat¡on that the materialfully compl¡es with the chosen material specification ¡n all respects.
4.1.5 When a tank is designed to üe requirements of this standard us¡ng plate material from Group-l throughGroup-lllA steels, the tank Manufacturer responsible for any proposed material subst¡tution to use GrouFlV throughGroup-Vl steels must do the follow¡ng.
a) Maintain all of the orig¡nal design criteria for the lower süess Group-l through Group lllA steels.
b) Obiain the prior written approval ofthe Purchaser.
c) Ensure that all of the design, fabr¡caüon, erection, and inspection requ¡remenb for the material be¡ng subsütutedwill meet the lower stress Group I through Group lllA specifications for items ¡nclud¡ng but not limited to:
1) material properties and production process methods;
2) allowable stress levels;
3) notch toughness;
4) welding procedures and consumables;
5) thermal stress relief;
4-1
API STANDARo 650
6) temporary and permanent attachment detrils and Procedures;
7) nondesructive examinations.
d) Include the pen¡nent ¡nformaüon ¡n the documents proúded to the Purchaser, including a certmcat¡on statementthat the substiuited material fully complies w¡th 4.1.5 ¡n all respects, and prov¡de all other records covered by the
work pocesses applied to thé material such as ¡mpact test¡ng, weld procedures, nondestructive examinaüons,
and heat Eeaúnents.
4.2 Plates
4.2.1 General
4.2.1.1 Except as otherw¡se provided for in 4.1, plates shall conform to one of the specmcat¡ons listed ¡n 4.2.2
through 4.2.6, subject to the modifications and limitations ¡n this standard.
4.2.1.2 plate for shells, roofs, and bottoms may be ordered on an edge-th¡ckness basis or on a weight (kgm2 [lb/ftzl)
basis, as spcified in 4.2.1 .2.'1, 4.2.'1.?.2, and 4.2.'1.2.3.
4.2.1,2.1 fhe edge üickness ordered shall not be less than lhe computed design thickness or üe minimum
permitted thickness.
4.2.1.2.2 rhewe¡ght ofdered shall be great enough to pfovide an edge th¡ckness not less than the computed des¡gn
th¡ckness or the m¡n¡mum perm¡tted thickness.
4.2.1.2.3 Whether an edge-thickness or a we¡ght bas¡s ¡s used, an undem¡n not more than 0.3 mm (0.01 in ) from
the computed de§¡gn th¡ckness or the minimum permitted thickness is acceptable.
4.2.1.3 All plates shall be manufactured by the open-hearth, electric-furnace, or basic oxygen process' Steels
produced Uy the tnermo-mechanical control process CIMCP) may be used, provided that the combination of
tnemicat cónposition and ¡ntegrated controls of the steel manufacturing ¡s mutually acceptable to. the Purchaser
and the Manuiacturer, and provided that the specif¡ed mechanical propert¡es in the required plate thicknesses are
achieved. Copper-bearing steel shall be used if spec¡fied by the Purchaser.
,f.2.1.4 Shell plates are l¡mited to a maximum thickness of 45 mm (1.75 ¡n.) unless a lesser th¡ckness ¡s statéd in this
standard or in ü|e plate specification. Plates used as inserts or flanges may be thicker than 45 mm (1 75 in.). Plates,
as designated ¡n ¿.Z.lO.i anO thicker than 40 mm (1.5 in.), shall be normal¡zed or quench temPered, killed, rnade to
f¡ne-gra¡n practice, and ¡mpact tested.
¡t.2.1.5 plate components not listed in 4.2.10.1 (i.e. nonpressure boundary compression .components) shall be
limited to the max¡mum thickness as designated by ASTM, CSA, lSO, EN, or other recogn¡zed nat¡onal standard.
4.2.2 ASTMSpecifications
plates that conform to the following ASTM specif¡cations are acceptable as long as the plates are within the stated
limitatiom.
a) ASTM A36ÍWA36 for ptates to a max¡mum thickness of 40 mm (1.5 ¡n.). None of the spec¡fications for the'
ujprrt"nunt ,"terials listed in Table 1 of ASTM A361VUA36 are considered accePtable for tanks consúucted under
tti¡i standard unless it is expressly stated in this standard that the specificaüons are acceptable.
b) ASTM A131t/uA131, Grade A, for plates to a maximum th¡ckness of 13 mm (0 5 in'); Grade B for plates to a
maximum th¡ckness of 25 mm (1 in.); and Grade EH36 for plates to a max¡mum th¡ckness of 45 mm (1 75 in )
(¡nsert plates and flanges to a max¡mum th¡ckness of 50 mm [2 in.l).
wEroED TANKS FoR OrL SToRAGE
c) ASTM A283M/A283, Grade C, for plates to a maximum thickness of 25 mm (1 ¡n.).
O ASTM A285fWA285, Grade C, for plates to a maximum thickness of 25 mm (1 in.).
e) ASTM A516M Grades 380, 415, 450, 485/A516, Grades 55.60,65, and 70, for plates to a maximum thickness of40 mm (1.5 ¡n.) (insert plates and flanges to a max¡mum thickness of l0o mm [4 in.D.
0 ASTM A537t\i4lA537, Class 1 and Class 2, for plates to a maximum th¡ckness of 45 mm (1.75 ¡n.) (¡nsert plates toa maximum th¡ckness of 100 mm [4 in.l).
g) ASTM A573M Grades 400, 450, 485/A573, Grades 58, 65, and 70, for plates to a maximum thickness of 40 mm(1.5 in.)-
h) ASTM A633M/A633, Grades C and D, for p¡ates to a maximum thickness of 45 mm (1.75 in.) (insert plates to amaximum thickness of 100 mm [4.0 in.]).
¡) ASTM A662t\r1A662, Grades B and C, for plates to a maximum thickness of 40 mm (1.5 in.).
j) ASTM A678tvUA678, Grade A, for plates to a max¡mum th¡ckness of 40 mm (1.5 in.) (insert plates to a maximumthickness of 65 mm [2.5 in.]) and Grade B for plates to a maximum ü¡ckness of 45 mm (1.75 ¡n.) (insert plates to amaximum th¡ckness of 65 mm [2.5 in.D. Boron add¡tions are not permined.
k) ASTM 4737t\illA737, Grade B, for plates to a maximum th¡ckness of 40 mm (1.5 ¡n.).
l) ASTM A841fWA841 Grade A, Class 1 and Grade B, Class 2 for plates to a maximum thickness of 40 mm (1.5 in.)(insert plates to a maximum thickness of 65 mm [2.5 in.l).
4.2.3 CSASpecif¡cations
Plate fumished ro csA G40.21 in Grades 260W(38Vy), 300W(44W), and 350W(50W) is acceptabte within rhel¡mfraüons stated below. (lf impact tests are requ¡red, Grades 260W[38VV|, 300W[44W, and 350W[50W aredesignated as Grades 260WT/[38UrL 30oWT/[44WTl, and 350WT/[50Wfl, respecüvely.) lmperial unit equivalenrgrades of CSA Spec¡fication G40.21, shown ¡n parenthes¡s, are also acceptable.
a) The W grades may be semi-k¡lled or fully kilted.
b) Fully killed steel made to fine-gra¡n practice must be specif¡ed when required.
c) Elements added for gra¡n refin¡ng or strengthen¡ng shall be restricted ¡n accordance w¡th Table 4.1 .
d) Plates shall have tensile strengths that are not more than 140 MPa (20 ksD above the m¡n¡mum specified for thegrade.
e) Grades 260W(38W) and 300W(44\ /) are acceptable for plate to a max¡mum thickness of 25 mm (1 in.) if sem¡-k¡lled and to a max¡mum th¡ckness of 40 mm (1.5 ¡n.) if fully killed and made to f¡ne-gra¡n pract¡ce.
Grade 350W(50w) is acceptable for plate to a maximum thickness of 45 mm (1.75 ¡n.) (insert plates to a rnaximumthickness of 10O mm [4 in.D if fufly k¡lled and made to f¡ne-gra¡n pract¡ce.
4.2.4 lSOSpec¡f¡cations
Plate furnished to ISO 630 in Grades E275 and E355 is acceptable within rhe follow¡ng limitaüons:
\- a) Grade E275 ¡n Qualiües C and D for plate to a maximum thickness of 40 mm (1.5 in.);
4-3
API STANoARD 650
Table 4.1-Maximum Perm¡ss¡ble Alloy Content
Alloy Heat Analys¡s (%) Notes
Columbium 0.05 1,2,3
Vanad¡um 0.10 1,2,4
Columb¡um (< 0.05 o/.) plus Vanad¡um 0.10 | 1,2.3
Nitrogen 0.015 I 1,2,4
Copper 0.35 1,2
Nickel 0.50 '1, 2
Chromium 0.25 I 1,2
Molybdenum 0.08 't, 2
NóTE 1 when the use of these allovs or clmbinations of them ¡s not irrcluded in the maleria¡ spec¡ficaÜon, theiru+ shall be at the oDtron of the olate óroducer, sub¡ect to the approval ol the Purchaser' These elements shall be.epone¿ wtren reqüeSed by the pürchase¡. Whén rnore rctiEictive limhaüons are ¡ncluded in the materialspecificat¡on, those shall govem.
NOTE 2 On product analys¡s, the rnaterial shall confom to these requirements, subjecl to the product analys¡stderances of úle specfication.
NOTE 3 When colúnbium ¡s added either s¡nqty or ¡n combination with vanadium, it shall be restricted to platesot 13 rñm (0.50 in.) maximum thickness unless c'oinb¡ned with 0 15 % minimum s¡l¡con.
NOTE 4 when niboqen (<O.Ol5%) is added as a supplement to vanadium, it shall be reported, and themin¡mum ratio o{ vanadíum to nitrogen shall be 4:1.
b) Grade E3SS ¡n Quatiües C and D for plate to a maximum th¡ckness of 45 mm (1.75 in.) (¡nsert plates to amaximum th¡ckness of 50 mm [2 in.]).
4.2.5 ENSpecif¡cat¡ons
plate tum¡shed to EN 10025 in Grades 5275 and 5355 ¡s acceptable within the following l¡mitations:
a) Grade 5275 ¡n Qual¡ües JO and J2 for plate to a max¡mum th¡ckness of 40 mm (1.5 ¡n.);
b) Grade 5355 in Qualities JO, JZ and K2 for plate to a maximum thickness of 45 mm (1.75 ¡n-) [¡nsert plates to a
maximum thickness of 50 mm (2 ¡n.)1.
4.2.6 NationalStandards
plates produced and tested in accordance with the requirements of a recogn¡zed national standard and with¡n the
mecha;ical and chemical l¡mitations of one of the gradés listed in Table 4.2 are acceptable when approved by the
eurcttaser. tne requ¡remenE of this group do not apply to the ASTM, CSA, lSO, and EN specif¡cations l¡sted in 4.2.2,
4.2.3, 4.2.4, and 4.:2.s. for üe purpoies bf this stanáárd, a naüonal standard is a standard that has been sancüoned
by the govemment of the country from wh¡ch the standard originates.
4.2.7 General Requ¡rements for Delivery
4.2.7.1 fhe marerial furnished shall conform to the appl¡cable requirements of the l¡sted specmcaüons but is not
restricted with respect to the location of the place of manufacure.
1.2.7.2 fhis material is ¡ntended to be suitable for fusion weld¡ng. Welding technique ¡s of fundamental ¡mportance,
and welding procedures rrust provide welds whose strength anó toughness are consistent with the.plate rnaterial
ü¡rg ñir"ü.hn welding pelormed to repair surface defú1s shall be done w¡th low-hydrogen welding elecrodes
comóáüue in chem¡stry, stfength, and quality with the plale rnaterial'
4-4
wELoED TaNKS FoR O[ SToMGE 4.5
4.2.7.3 When spec¡fied by the plate purchaser, the steel shall be fully killed. When specified by the pla¡e purchaser,
fully killed steel shall be made to fine-grain practice.
4.2.7.4 For plate that is to be made to specil¡caüons that limit the max¡mum manganese content to less than 1 .60 %,
üe limit of thé manganese content may be ¡ncreased to 1.60 7" (heat) at the option of the date producer to ma¡nta¡n
the requ¡red strength level, provided that the maximum carbon content is reduced to 0.20 % (heat) and the weldabil¡ty
of the ilate ¡s given cons¡deration. The mater¡al shall be marked "Mod'follow¡ng the specificaüon l¡sting. The material
shall conform to the product analysis tolerances of fable B ¡n ASTM A6lvUA6'
4.2.7,5 The use or presence of columbium, vanadium, nitrogen, copper, n¡ckel, chromium, or molybdenum shall not
exceed the l¡mitations of fable 4.1 for all Group Vl mater¡als (see Table 4.4a and Table 4.4b) and ISO 630, Grade
E355.
4.2.8 Heat Treatment of Plates
4.2.8.1 When specmed by the plate purchaser, fully killed plates shall be heat treated to produce grain ref¡nement by
e¡ther normal¡zing or heat¡ng uniformly for hot forming. lf the requ¡red treatrnent is to be obiained ¡n conjunction withhot fom¡ng, the temperature to which the plates are heated for hot forming shall be equ¡valent to and shall not
s¡gnif¡cantly exceed the normal¡zing temperature. lf the treatment of the plates ¡s not specmed to be done at the plate
producer's plant, testing shall be canied out ¡n accordance with 4.2.8.2.
,f.2.8.2 When a plate purchaser elects to perform the required normal¡z¡ng or fabricates by hot form¡ng (see 4.2.8.1),
the plates shall be accepted on the bas¡s of m¡ll tests made on full-thickness spec¡mens heat treated ¡n accordancewith the plate purchaser's order. lf the heat-¡reatment temperatures are not ¡nd¡cated on the contracl the sPecimens
shall be heat treated under condit¡ons cons¡dered appropriate for grain refnement and for rneeting the testrequirements. The plate producer shall ¡nform the plate purchaser of the procedure followed in treating the specimensat the steel m¡ll.
4.2.8.3 On the purchase ordet the plate purchaser shall ¡nd¡cate to the plate producer whether the producer shallperfom the heat treatment of the plates.
4.2.8.4 The tensile tests shall be pelormed on each plate as heat treated.
Table 4.2-Acceptable Grades of Plate Material Produced to Nat¡onal standafds (see 4.2.6)
Mechanical Properl¡es Chemical Compos¡tion
Tensile Strengtha
Minimumc Maximum
Gradeb MPa ksi MPa ks¡ MPa ks¡ mm ¡n. Heat Producl Heat f'roduct
?o 0.75 0.20 0.24 0.04 0.05
40 1.5 0.23 0.21 0.04 0.05
40 1.5 0.25 0.29 0.04 0.05
MinimumYield
StrengthcMax¡mumThickness
Max¡mumPercentcarbon
MaximumPercent
Phosphorus andSulfur
235d 360 52 510 74
zfi 4m 58 530 17
275 430 62 560 81
235 34
250 36
215 40
a fhe loc¿lbn and number of tes specirlens, elongatioo and bend tests, and acceptance criteria are to be ¡n accoldarce wilh lhe appropr¡ate
mtimal gandard, ISO star¡dard, o. ASTM specification
b Semlki[ed or fu y kiled quality; as rolled or TMCP (20 mm [0.75 in.] rnax¡mLm wñen TMCP is used in place of rprmalized steel), ormfmalized.
c yield srength = tensle srength s 0.75, based on üe minirum specif¡ed yield and ten§le súengiñ unless aclual te$ values are requ¡red by
the Pufchasef.
d Nonrimming only.
.l
API STANoARD 650
4.2,9 lmpact Testing of Plates
,[.2.9.1 When required by the Purchaser or by 4.2.10, a set of Charpy V-notch ¡mpact spec¡mens shall be takenfrom plates after heat treatment (if the plates have been heat treated), and the spec¡mens shall futf¡ll the statedenergy requ¡rements. Test coupons shall be obtained adjacent to a tens¡on-test coupon. Each full-size impactspec¡men shall have iE central ax¡s as close to the plane of one-quaner plate th¡ckness as the plate th¡ckness w¡llpermit.
4.2.9.2 When it ¡s necessary to prepare test specirnens from separate coupons or when plates are furnished by theplate producer in a hot-rolled cond¡tion w¡ü subsequent heat treatTent by the fabricator, the procedure shall conformtO ASTM A2O.
4,2.9,3 An ¡mpact test shall be performed on three spec¡mens taken from a s¡ngle test coupon or test locat¡on. Theaverage value of the specimens (with no rnre than one spec¡rnen value be¡ng less than the specif¡ed min¡mumvalue) shall comply with the specmed minimum valué. lf rnore than one value is less than the specified min¡mumvalue, or if one value ¡s less than two-th¡rds the spcmed m¡n¡mum value, three add¡t¡onal specimens shall be tested,and each of these must have a value greater than or equalto the specif¡ed m¡n¡mum value.
4.2.9.4 The test specinens shall be Charpy V-notch Type A spec¡mens (see ASTM A370), with the notchprpend¡cular to the surface of the plate being tested.
4.2.9.5 For a plate whose thickness is insuffic¡ent to permit preparaüon of full-size spec¡n¡ens [10 mm x 10 mm(0.394 ¡n. x 0.394 ¡n.1, tests shall be made on the largest subs¡ze spec¡mens that can be prepared from the plate.Subs¡ze spec¡mens shall have a údth along the notch of at least 80 % of the material th¡ckness.
¡1.2.9.6 The impact energy values obtained from subs¡ze spec¡rnens shall not be less than values that areproportional to the energy values requ¡red for full-size spec¡mens of the same mater¡al.
¡t.2.9.7 The testing apparatus, ¡ncluding the cal¡bration of impact machines and the perm¡ss¡ble variations ¡n thetempera[Íe of specimens, shall conform to ASTM A370 or an equivalent testing apparatus confom¡ng to nat¡onal
standards or ISO standards.
4.2.10 Toughness Requ¡rements
4.2.10.1 The üickness and des¡gn metal temperature of all shell plates, shell reinforcing plates, shell ¡nsert plates,
bonom plates welded to the shell, dates used for manhole and nozzle necks, plate-ring shell-nozzle flanges, blindflanges. and manhole cover plates shall be ¡n accordance with F¡gure 4.1a and Figure 4.1b. Notch toughnessevaluation of plate-r¡ng flarEes, blind flanges, and manhole cover plates shall be based on "governing th¡ckness" asdefined in 4.5.4.3. ln addition, plates more than 40 mm (1.5 in.) thick shall be of k¡lled steel made to fine-grain practice
and heat treated by normal¡z¡ng, normaliz¡ng and temper¡ng, or quench¡ng and temper¡ng, and each plate as heattreated shall be ¡mpact tested accofdlng to 4.2.11.2. Each TMCP A841 plate-as-rolled shall be impact tested. lmpacttest temperatJre and required energy shall be ¡n accordance with 4.2.11.2 ¡n lieu of the default temperatrre and
energy gúen in A841.
4.2.10.2 Subjecl to üe Purchaser's approval, thermo-rnechanical-conúol-process (IMCP) dates (plates podrcedby a mechan¡cal-thermal rolling process designed to enhance notch toughness) may alternaüvely be used wherehéat treated plates are normally required by 4.2.10.1 because of thickness over 40 mm (1.5 ¡n.). ln this case, each
TMCP plate-as-rolled shall receive Charpy V-notch ¡mpact energy testing ¡n accordance with 4.2.9, 4.2.10, and4.2.1'1. When TMCP steels are used, cons¡derat¡on should be given to the service condit¡ons outlined ¡n 5.3.3.
4.2,10.3 Plates less than or equal to 40 mm (1 .5 in.) th¡ck may be used at or above the design metal temperaires¡nd¡ca¡ed in F¡gure 4.1a and F¡gure 4.1b without be¡ng impact tested. To be used at des¡gn metal temperatures lower
than the temperatures indicated ¡n F¡gure 4.la and Figure 4.1b, plates shall demonstfate adequate notch toughnessin accordance with 4.2.11.3 unless 4.2 .11.2 or 4.2.11.4 has been specmed by the Purchaser. For heat-feated matefial
\A/ELoEo T^NKS FoR OT- SToRAGE
10
_10
p
E -r5E.9 -20E
: -2s-9r
ó -30
r020
fh¡cknBss, hduding coÍos¡on allo,vance
NOTE 1 The Group ll and Group V lines coiñcire at üi;kn$ses less han t3 mm.
NOÍE 2 The Group lll and Group lllA l¡nes co¡nc¡de ai lhiroess€s hss than 13 mm.
NOÍE 3 The materiab in eacfi gloup are listed ¡n Table 4.4a and Table ¿t.¡lb.
NOTE 4 OobLd.
NOTE 5 Use üle Group llA and Group VlA.¡¡rves tur p¡pe and larggs (s€e,t.5.4.2 and 4.5.¡t,3).
NOTE 6 . Linear equat¡ons provired ¡n Table 4.3a can be us€d lo calculate Des¡gn Metal TemperatuG (OtufD for eaá API malerial groupand the hk*ness .anoe.
Figure ¡l,la- lnlmum P.7mis3lblo Dés¡gn ¡l.tal Tompeatur€ for MateriaE Used ¡n Tank Shelb withoutlmpact T$üng (Sl)
(normalized, nomalized and temp€red, or quenched and tempered), notch toughness shall be demonstrated on eachplate as heat treated when 4.2.11.2 requirements are specified. lsothermal lines of lowest one.day mean temperafureare shown in Figure 4.2.
4.2.10.4 Plate used to reinforce shell open¡ngs and ¡nsert plates shall be of the same material as the shell plate towhich they are attached or shall be of any appropriate material l¡sled ¡n Table 4.4a, Table 4.4b, F¡gure 4.1a, andFigure 4.1b. Except for noz¿e and manway necks, the material shall be of equal or greater yield and tens¡le strengüand shall be compat¡ble with the adjacent shell material (see 4.2.10-1 and 5.7.2.3, ltem d).
4.2.'10.5 The requirements in 4.2.10.4 apply only to shell nozzles and manholes. Materials for roof nozzles andmanholes do not require spec¡al toughness.
0mm 56
4-7
t3t5
4-8 API §ANoaRo 650
60 60
50
,o
30
20
'10
0
-t0-11
-20
-30
-40
-50
-60
e
§. ,oE
EOE
.6 -roo
á
o$3)'::- -"*-/- _a-/-.¿-
-'-:2v'6,») --rl-Z'-§ -./
7 g,""
-3
See NotE 1
GlY
,,1
n8
I-n\\
- -
s9I" 6,owvr{$vlA
I
Group lllA
.* I"l 2
0.3750.00 in. 1.25 1.50
Th¡ckness, ¡ndud¡¡g conos¡or allowance
NOTE I Th€ Group ll and Gror¡p V l¡nes cdncire at ti¡do€ss€§ le3s than 1/, ¡n.
NOTE 2 th€ Grot¡p lllarx, Group lllA l¡nes coindd€ st tlid(ng§s€s hss ülan r/2 ¡n.
NOTE 3 The mabdsb ¡n each 0roup are l¡sbd ¡n Table 4..la and Tabls.l.4b.
NOTE 4 Del.n d.
NOTE 5 Use th€ Gloup llA 8nd Group \4A curves tur pipo and fames (§€e,a.5.¡t2 and ¡1.5.,1.3).
NOTET L¡near equalions Fovided ¡n Tabl€,ú.3b can bs us€d to cálo¡hb O€8¡gn Metal femperature (OMf) br eadr APlmaterialgroup andü€ h¡ckness rangs.
F¡gurr 4.lH¡n¡mum Pem¡ss¡ble DG¡gn lÍotal Temperat¡ro for matorla¡s Us6d ln Tank Shells úthoutlmpact Te3üng (USC)
4.¿l1 ToughnessProceduE
¿L2.11.1 Vvhen a material's toughness must b6 detérminéd, it shall be done by one of the procedures described in4.2.11.2,4.2.11.3, and 4.2.11.¡+, as specmed in ¿1.2.10.
¡L2.'t1.2 Each pláe as mlled or heat feated shall be ¡mpad tested in accordancs with 4.2.9 at or belo/v the designmetal temperature to show Charpy V-notcñ longitud¡nal (or transverse) values thal fumll the m¡nimum requ¡rements ofTable 4.5a and Table 4.5b (see 4.2.9 for the m¡n¡mum values for one specimen and for subsize specimens). As usedhere, the tem plate as rolled refers to the unit plate rolled tom a slab or direcüy from an ¡ngot ¡n its relat¡on to thelocation and number of spec¡mens, not to the condiüon of lhe plate.
1.00
' n"'P]
wELoEo TaNts EoR OtL SToRAGE 1- 11
Table 4.4a-Material GrouPs (Sl)
(See F¡gure 4.1a and Note'l below)
Group I
As Rolled,Semi-Killed
Grorp llAs Rolled,
Killed or Sem¡-Killed
GrouP lllAs Rolled, Killed
F¡ne-Grain Practice
GrouP lllANormalized, K¡lledFineGra¡n Practice
Mater¡al Notes Material Notes Maler¡al Notes Málerial Notes
A283M C 2 4131M B 6 A573M-400 A573lvl-400 IA285M C 2 A36M A516M-380 A516M-380 9
A131r\¡ A 2 G40.21-260W A516M-415 A5',l6M-4.15 IA36M Grade 250 7 G40.2',1-260W I G40.21.260W 8,9
Grade 235 3 Grade 250 Grade 250 8,9
Grade 250 5
Group lVAs Rolled, K¡lled
Fine-Gra¡n Practice
Group IVAAs Rolled, Killed
Fine.Grain Pract¡ce
Group VNormal¡zed, K¡lledF¡neGra¡n Pract¡ce
Group VlNormalized or
Quenched and Temp€red,Killed Fine-Gra¡n Practice
Reduced Carbon
Mater¡al Notes Material Notes Mater¡al Notes Material Notes
A573M-450 A662M C A573M-485 9 A]31M EH 36
A573M-485 A573M-485 10 A516M,450 I A633lvl C
A516M-450 G40.21-300W 8, 10 4516M-485 I 4633M D
A516M-485 G40.21,350W 8, 10 G40.21-300W A537M Class 1
A662M B E275 D G40.21,350W 8,9 A537M Class 2 12
G40.21-300W 8 E355 D A678M A
G40.21-350W B s27 5 )2 8 A678tvl B 12
E2't5 C B5355 (J2 or
K2)B A737M B
E355 C
s275 J0
s355 J0
8
8
8
A841M, Grade A, Class 1
A841M, Grade B. Class 2
11,12,1311, 12, 13
crade 215 INOTES1 Mr¡sr of ttle ti§ed máreriat soecif¡cation numbers refer to ASTM soecif¡cations (includhq Grade or Clas§); Úlere are, however, some"
áñel*m!, c¿ó.il tir¡clu¿¡nó'éáoél ¡s a csA sDec¡f¡caüm; Grades E2?5 and E355 (¡rrclLÚ¡rE Qualrty) are contained ¡n lso 630; Grades5ii{án¿ §¡sltrrcütng quiúÍáié órna¡n"¿ ín ENlm25; and Grade 235, Grade 250. andcrade 275 are related to natiqral slandards(see 4.2.6).
2. Mr6t be sem¡-k¡lhd or kill€d.
3. Thickness s 20 mm.
4. Ddet€d.5. Mámánese corlem shall be O.8O % to 1.2 % bv heat analvsis for th¡cknesses Ceater than 20 mrn, excepl that for each reduclbn oÍ 0.01 %-
¡eloü ü'lá soecme¿ carbon maxirrum, an ir¡creáse of 0.06 % .rEnOanese abqre-ü|e speciñed maximum will be perrÚned up to the maximumof L35 %. fhickr¡esses < 20 rfm shall have a rnarEanese conteniof 0.80 % to 1.2 % by heat anatys¡s.
6. Th¡ckness s 25 mm.
7. Must be k¡lled.
8. Musr be k¡lled and made to fine-gra¡n praclhe.
9. Must be normal¡zed.
10.Mrst have chemisry (heat) riodifed to a max¡mum carbon cooteff ofO.m and a marimun Íuinganese contem ol1.60 % (see 4.2.7.4).
11. Prodrced by the ttErrño-riechanical conúd process CrMCP).
12. See 5.7.¡i.6 for tests on s¡mulated tes¡ coupons for rEterial used in súess-relieved ass€rnbl¡es.
1 3. S€e ,1.2.1 0 for ¡mpacr Gst requiremeris (each date-as-rolled tested).
4-12 API STANDARo 650
(See Figure 4.1b and Note 1 below.)
Group I
As Rolled,Sem¡-killed
Group llAs Rolled,
K¡lled or Sem¡-ki¡led
Group lllAs Rolled, K¡lled
Fine-Grain Pract¡ce
Group lllANormal¡zed, KilledFine-Gra¡n Practice
Mater¡al Notes Mater¡al Notes Material Notes Material Notes
4283 C 2 A131 B 6 4573-s8 4573-58 I4285 C 2 436 2q 4516-55 4516-55 I4131 A 2 G40.21-38W 45r6,60 4516,60 9
436 )1 Grade 250 1 G40.21-38W B G40.21-38W 8,9Grade 235 3 Grade 250 I Grade 250 8,9Grade 250 5
Group lVAs Rolled, K¡lled
F¡necra¡n Practice
Group IVAAs Rolled, K¡lled
Fine.Grain Pract¡ce
Group vNofmal¡zed, KilledF¡ne-Grain Pracl¡ce
Group VlNormalized or
Quenched and Tempered,K¡lled F¡ne-Grain Pract¡ce
Reduced Carbon
Material Notes Mater¡al Notes Material Notes Material Notes
A573-6s A662 C 4573-70 9 A131 EH 36
4573-70 4573-70 10 4516-65 9 4633 C
45r6.65 G40.21,44W 8, '10 4516-70 9 4633 D
4516-70 G40.21-50W 8, 10 G40.2'l-44W 8.9 4537 Class 1
4662 B E215 0 G40.2'r-50W 8,9 4537 Class 2 12
G40.2'1,44W I E355 D 4678 A
G40.21-50W B s215 J2 8 4678 B 12
E275 C 8 5355 (J2 or K2) 8 4737 B
E355 C
s275 J0
s355 J0
8
8
8
4841, Grade A, Class 1
4841, Grade B, Class 2
11,12, 13
11,12, 13
Grade 215 8
NOTES
1. Most ol úle listed rnaterial speciñcatixr nunü€rs refer to ASTM specificalbos (¡nclud¡rE Grade or Class); úlere ae, hon¡ever, soíEexceptbns: G40.21 (includirE Grade) is a CSA specificatlr; Grades E275 and E355 (¡rdúring QualM are cortained in lso 630; Grades5275 ar¡d 5355 (¡r¡clud¡ng quatty) ae cortained ¡n EN1m25; and Grade 235, Grade 250, and Grade 275 are reliated to national slandads(see 4.2.6).
2. Must be sem¡-k¡lled or k¡lled.
3. Thicknéss < O.75 in.
,{. Ddeted.
5. Mangar¡es€ contert sha[ be 0.&r% to 1.2 % by tEat anatysis fc tt**riesses qfeat€r lhan 0.75 h., erceÉ ú|at lü eaó reducrioo o10.01 %beb'¡ the specified cübon maxinxrn, an irErease of 0.06 % manganese above ú|e speciñed maimum úll be permined W 10 üle rnaxirrumof 1.35 %. Thdoesses < 0.75 ¡n. shall have a manganese coneri ol0.8O % to 1.2 % by heat amlysis.
6. Ttickness s l in.
7. Mtst be killed.
8. Must be k¡lled and made to fine-gfa¡n practice.
9. Mus¡ be rErmal¡zed.
10. Musr have chernisry (hear) r¡odiñed to a maximum carboo coñent oÍ 0.20% and a max¡rrum m¡mganese cootent ol 1.60 % (see 4.2.7.4).
11. Prodr¡ced by úe úemD-rnechanhal conüol process (TÍ\¡CP).
1 2. s€e 5.7.,t.6 fq tesa on s¡rrulated ted coupons for material LE€d h sfess{elÉved assemH¡es.
1 3. See ,t.2.1 0 fo. ¡rpacl test requiemerüs (each phte-as{olled tesred).
Table 4.4b-lt aterial Groups (USC)
wELoED TaN(s FoR OtL SToMGE 4-',t 3
Table 4.sa-M¡nimum lmpact Test Réquirements for Plates (Sl) (See Note)
Pláte Mater¡ala and Thickness (¿ in mm
Th¡ckness
Average lmpact Value ofThree Specimenso
Longitudinal Transverse
mm ) )
Groups l, ll. lll, and lllA
/< maximum lhicknesses in 4.2.2 through 4.2.520 18
croups lV lVA, V and Vl (except quenched and tempered and TMCP) r< 40
40<r<45
45<f<50
50 < t< 100
4-l
48
54
68
27
34
41
54
Group Vl (quenched and tempered and TMCP) ¿< 40
40<r<45
45<¿<50
50<¡<lm
48
54
61
68
34
4',!
48
54
6 See Table 4.4a.
b lriterpolation is pe,mmed to üe nearestFule.
NOTE For plate ring f,anges, úe m¡rimum ¡rpact test requ¡rernents for all tlr¿*nesses shall be úlose for ,< ,tO mm.
Table 4.5b-Minimum lmpact Test Requ¡rements for Plates (USC) (See Note)
Plate Mater¡ala and Thickness (0 in lnches
Thickness
Average lmpact Value ofThree Specimensb
Long¡tud¡nal Transverse
an. ft.tbf ft-tbf
Groups l, ll, lll. and lllA
,< max¡mum thicknesses ¡n 4.2.2 through 4.2.515 13
Groups lV lVA, V and Vl (excepl quenched and tempered and TMCP) r< 1.5
1.5 < r< 1.75
1.75 < t<22<t<4
30
35
40
50
?n
25
30
40
Group Vl (quenched and tempered and TMCP) ¡< 1.5
1.5 < r< 1.75
1.75 < t<22<t<4
35
40
45
50
25
30
35
40
a See Table 4.4b.
b fÍerpolalbn ¡s permiued to úe nearest ftlbf.
NOTE For date ring ffanges, the m¡n¡mum ¡ñpacl test reqdrernents fd allh¡cknesses shallbe ihose for ,< 1.5 in.
4-14 API SIANDARo 650
d) §ructural Steels l¡sted ¡n AISC, Manual of $eel Construction.
e) CSA G40.21, Grades 260W(38W), 300W(44W), 350W(50w), 260WT(38WT), 300WT(44WT), and350WT(50WT). lmperial unit equivalent grades of CSA Specificaüon G40.21, shown in parenthesis, are alsoacceptable.
0 ISO 630, Grade E275, Qualiües B, C, and D.
g) EN 10025, Grade 5275, Qualiües JR, J0, and J2.
h) Recognized national standards. §ructural steel that ¡s produced ¡n accordance with a recognized nat¡onalstandard and that meets the requ¡rements of Table 4.2 ¡s acceptable when approved by the Purchaser.
4,4.2 All steel for structural shapes shall be rnade by the open-hearth, eleclr¡c-fumace, or basic oxygen process.Copper-bearing steel ¡s acceptable when approved by the Purchaser.
4.4.3 Not all of the súuctural steel shapes listed ¡n AISC (4.4.1 [dl) and orher national standards (4.4.1[hl) are wellsuited for weld¡ng. Material selection for struclural shapes requ¡ring welded connections shall include confirmaüon ofthe material's weldab¡lity from the structural shape Manufacturer, other reputable sources, or by weld testing.Strucural steel shapes hav¡ng poor weldab¡lity shall only be used for bolled connect¡on designs.
4.4.4 Weldable-quality pipe that conforms to the physical propenjes specif¡ed in any of the standards l¡sted in 4.5.1may be used for strucural purposes with the allowable stresses stated in 5.'10.3.
4.5 Piping and Forgings
¿1.5.1 Unless otherwise specmed ¡n th¡s strndard, p¡pe and pipe coupl¡ngs and forg¡ngs shall confom to thespecif¡cations listed ¡n 4.5.1.1 and 4.5.1.2 or to Müonal standards eq.¡ivalent to the speciñcations listed.
4.5,1.1 The follo ,ing specifications are acceptable for tipe and dpe coupl¡ngs:
a) API Spec 51, Grades A, B, and X42;
b) ASTM A53tvUA53, Grades A and B;
c) ASTM A106 túA106, Grades A and B;
d) ASTM A234fvUA234, Grade WPB;
e) ASTM A333?rV4333, Grades 1 and 6;
D ASTM A334fvl/A334, Grades 1 and 6;
g) ASTM A4201WA420, Grade WPL6;
h) ASTM A524, Grades I and ll;
¡) ASTM A671 (see 4.5.3).
,1.5.1.2 The follorving specmcabns are acceptable for forg¡ngs:
a) ASTM A105ttrUA105;
b) ASTM A181M4181;
c) ASTM A350M/A350. Grades LF1 and LF2.
a
a
WETDED TANKS FoR OIL SIoRAGE 4-15
¡1.s.2 Unless ASTM A671 p¡pe ¡s used (electric-fus¡on-welded pipe) (see 4.5.3), mater¡al for shell nozzles and shell
manhole necks shall be seamless pipe, seamless forging, or ptáte material as specified ¡n 42'101 When shell
;reriats are croup tV tVA, V, or Vi,'seamtess pipe sñaticompy with ASTM A106, Grade B; ASTM A524; ASTM
A3331WA333, Grade 6; or ASTM A334¡rVA334, Grade 6.
4.5.3 When ASTM A67l pipe ¡s used for shell nozzles and shell manhole necks, it shall comply w¡th the follow¡ng.
a) Material selecüon Shall be l¡mited to Grades cA 55, CC 60, Cc 65, CC 70, CD 70, cD 80, CE 55, and CE 60.
b) The pipe shall be pressure tested in accordance with 8.3 of ASTM 4571'
c) The plate specificat¡on for the P¡pe shall satisfy the requirements of 4.2.7, 4.2.8, and 4 2 9 that are appl¡cable to
that plate specmcation.
d) lmpacl tests for qualifying the welding procedure for the pipe longitudinal welds shall be Pefformed in accordance
with 9.2.2.
4.5.¡t Except as covered ¡n 4.5.3, the toughness requirements of p¡pe and forgings to be used for shell nozzles and
manholes shall be established as described in 4.5.4. 1, 4.5.4.?, 4.5.4.3, and 4.5 4 4'
4.5.4.1 P¡ping marerials made according to ASTM A333¡ruA333, A334fvvA334, A350M/A350, and A420, Grade
WpL6 may'be"useO at a Oesign métaitemftrature no lower than the ¡mpact test temPerature required by the ASTfirPi
specif¡caüán for the applicablé material grade without addit¡onal ¡mpact tests (see 4.5.4.4).
4.5.4.2 Oüer p¡pe and forging mater¡als shall be classified under the material groups shoun ¡n Figure 4.1a and
F¡gure 4.1b as follows:
a) Group [A-Apt Spec 51, crades A, B,and X42; ASTM Al O6lvl/A106, Grades A and B; ASTM A53tvüA53, Grades' n aná e; nsr¡, n:r 81fvuA181; ASTM A l O5tuA105; and A234twA234, Grade WPB;
b) Group VIA-ASTM A524, Grades I and ll.
4.5.4.3 The materials ¡n the group6 listed ¡n 4.5.4.2 may be used at nominal thicknesses, ¡nclud¡ng conos¡on
allowance, at a des¡gn maal teirpeiature no lower than thoie shown in Figure 4.1a and Figure 4_.lb without impact
test¡ng (see 4.5.4.4 ánd Figure +.'a). fte goveming th¡cknesses to be used in F¡gures 4.1a and F¡gure 4 1b shall be
as follows:
a) for bun-weldedjo¡nts, the nominal th¡ckness of the th¡ckest weldedjoint;
b) for corner or lap welds, the thinner of the two partsjo¡ned;
c) for nonwelded parts such as bolted bl¡nd flanges and manhole covers, 1/¿ of their nominal thickness.
¡1.5.4.4 When ¡mpact tests are required by 4.5.4.1 or 4.5.4.3, they shall be performed.in accordance with the
requ¡rements, ¡nclüd¡ng the minimum energ-y requirements, of ASTM A333¡rUA333, Grade 6, for pipe or ASTM
A3'5O[IVA35O, Grade L-Fl, for forgings at a test tempefature no higher than the des¡gn metal temperature' Except for
the plate specified ¡n 4.2.9.2, the-ma-terials specified in 4.5.1 and 4.5.2 for shell nozzles, shell manhole necks, and all
forgings uieO on shell open¡ngs shall have a m¡n¡mum Charpy V-notch ¡mpact strengü of 18 J (13 ftJb0 (full-s¡ze
spec¡men) at a temperature no h¡gher than the design rnetal temperatre.
4.6 Flanges
. 4.6.f Sl¡p on, ring-type, weld¡ng neck, long welding neck and lap jo¡nt flanges shall confom to the material
requirements of aSUE 816.5 for forged carbon steel flanges. Plate material used for nozzle flanges shall have
4-16 API STANDARD 650
-L
T
IT
l_
T
NOTE 1 Shgll reinforcing date ¡s not includ€d ¡n thesa ¡lluslrá¡ons.
NOTE 2 fs = shell th¡c¡(ness; f, = noz¿e neck U'¡¡c*ness: Ir = f,ange b¡ckness; fc = bolted cover thickn€ss.
NOTE 3 The govern¡ng th¡ck¡ess for each cornporierit shall bg as follor./si
l_
T]_
T
CorñponeñtsGowming Th¡d(n€ss
(th¡nner of)
¡,lo¿á€ n€ck at shdl
Sl¡porl flange and node n€ck
R¡netlDe flange afld nod€ n6d(
Weld¡ng.n€d( flangg and node n€d(
Loog wdd¡ng-ned( flal|g8
NonrvÉld€d bolted covs
Lapttf€ idnt Aang€
1,, or fs
ho¡ Tr
tn o¡ Tl
hf¡ or ts
1l¿ T"
tn or Tl
F¡gure 4.3-Governing Thickness for lmpact Test Determination of Shell Nozzle andManhole Mater¡als (see 4.5.4.3)
Slip-on Flange Ring-fype Flange
Lap Joint Flangs
Welding-Néck FlañgG Long Weld¡ng.Neck Flange
wELoED TaNKS FoR OtL SToRAGE
\-- physical properties bener than or equal to those required by ASME 816.5. Shell-nozzle flange material shall conform
ioi.Z.lO.f and 4.2.10.2. Lapjoint flanges shall not be used without the approvalofthe Purchaser.
. 4.6.2 For nominal pipe sizes greater than NPS 24, flanges that conform to ASME 816.47, Series B, may be used,
subject to the purcn'aser's aiproval. Particular attentión should be g¡ven to ensuring that mating flanges of
appurtenances are compatible.
4.7 Bolt¡ng
. a) Unless otherw¡se specified on the Data Sheet, Table 2, flange bolt¡ng shall conform lo ASTM A193 87 and the
dimensions specmóO in ASME 818.2.1. Nuts shall conform to ASTM A194 Grade 2H and the dimens¡ons
spec¡fied in A§ME 818.2.2. Both shall be heavy hex pattem. All bolts and nuts shall be threaded ¡n accordance
with ASME 81.13M (Sl), or with ASME 81.1(US) as follows:
1) bohs uP to and ¡ncluding 1 ¡n. diameter: UNC Class 2A ftt
2) nuts for bolts up to and ¡ncluding 1 ¡n. diameter: UNC Class 28 fit
3) bolts 1.125 in. diameter and larger: 8N Class 2Afit
4) nuts for bolts 1.125 ¡n. d¡ameter and larger: 8N Class 28 fit
o b) Unless oüen¡¡se spec¡f¡ed on the Data Sheet, Table 2, anchors shall be one of the following:
1) round bar to ASTM A36, threaded and galvanized;
\- 2) bohs to ASTM F1554, Grade 36, galvanized.
Nuts for anchors shall be galvanized heavy hex. Welding ¡s not permitted on anchors that are galvan¡zed.
. c) All other bolting shall conform to ASTM A3O7 or A193fvUA193. A325fvl/A325 may be used for structural purposes
only. The Purcñaser should specify on the order what shape of boh heads and nuts is des¡red and whether regular
or heavy dimensions are des¡red.
4.8 Welding Electrodes
4.8.1 For the weld¡ng of materials with a min¡mum tensile strength less than 550 MPa (80 ksi), the manual arc-
welding electrodes sñall conform to the E6O and 870 classificaüon ser¡es (suitable for the electric cunent
characteristics, the posit¡on of welding. and other condit¡ons of intended use) ¡n AWS A5.1 and shall conform to
7.2.1.10 as applicable.
4,8.2 For the welding of materials with a m¡n¡mum tens¡le strength of 550 MPa to 585 MPa (80 ks¡ to 85 ks¡), the
manual arc-weld¡ng electrodes shall conform to the E80XX-CX class¡ficaüon series ¡n AWS 45.5.
4.9 Gaskets
4.9.1 General
. ¡t.9.1.1 Gasket materials shall be specmed in Table 3 on the Data Sheet. Unless otherwise specified by thePurchaser, gasket materials shall not conta¡n asbestos.
4-11
4-',t8 API STANDARo 650
4.9.1.2 Sheet gaskets shall be conünuous. Metal gaskets made continuous by weld¡ng are acceptable if the weld isground flush and finished the sarne as the unwelded portion of the gasket. Rope or tape gaskets shall haveoverlapped ends.
4.9. 1 .3 Each gasket shall be rnade with an integral centering or posiüon¡ng device.
. ¿1.9.1.4 Nojo¡nt sealing compound, gasket adhes¡ve, adhes¡ve position¡ng tape, or lubricant shall be used on theseal¡ng surfaces of gaskes, or flanges duringjo¡nt makeup unless specmcally allowed by the Purchaser. When thesematerials are approved by the Purchaser, cons¡derat¡on should be given to chem¡cal compatib¡lity with the gasket andflange materials.
. ¡t.9.1,5 Spare gaskets are not requ¡red unless specif¡ed ¡n the Data Sheet, L¡ne 23.
4,9.2 Service
. When service gaskets are des¡gnated to be fumished by the Manufaclurer, the gaskets prov¡ded shall be as specmed¡n the Data Sheet, Table 3.
4.9.3 Test
. 4.9.3,1 Test gaskets must have comparable dimensions and compress¡bilit¡r character¡st¡cs as service gaskets.Descripüons of gaskets for temporary use only as test gaskets shall be submined for Purchaser's approval.
4.9.3.2 For jo¡nts that will not be d¡sassembled after testing, the test gasket rut be the spec¡f¡ed service gasket.
¡1.9.3.3 Except for stainless steel bolting, flange bols and nuts used for testing are acceptable for use in thecompleted tank.
SECTION 5_DESIGN
5.1 Joints
5.1.1 Definitions
The definitions in 5.'t.1.1 through 5.1.1.8 apply to lankjoint des¡gns. (See 9.1 for definilions that apply to welders and
welding procedures. See Section 3 for addit¡onal def¡nit¡om )
5.1.1.1butt-weldA weld placed in a groove between two abutting members. Grooves rnay be square, V-shaped (s¡ngle or double), or
U-shaped (s¡ngle or double), or they may be either single or double beveled
5.1.1.2double-welded butt jointAjo¡nt between two a-butt¡ng par6 lying in approximately the same plane that is welded from both s¡des.
5.1.1.3double-u,elded laP jointA joint between two overlapping members ¡n wh¡ch the overlapped edges of both members are welded with lillet
welds.
5.1.1.4f¡llet weld
\_ A weld of approximately úiangular cross-section thatjo¡ns Nvo surfaces at approximateiy right angles, as ¡n a lapjoint,
tee Jotnt, of comer Jolnt.
5.1.1.5full-fillet weldA f¡llet weld whose s¡ze ¡s equal to the th¡ckness of the thinnerjo¡ned member.
5.1.1.6single-welded butt jo¡nt wilh back¡ngA jo]nt between two abutting parts lying in approximately the same plane thal is welded from one side only with the
use of a str¡p bar or another suitable backing mater¡al.
5.1.1.7s¡ngle-u,elded lap jointA jo¡nt between two overlapp¡ng members ¡n wh¡ch the overlapped edge of one member ¡s welded with a fillet weld.
5.1.1.8tack weldA weld made to hold the pans of a weldment ¡n proper alignment until the f¡nal welds are made.
5.1.2 Weld S¡ze
5,1.2.1 The s¡ze of a groove weld shall be based on the jo¡nt penetration (that is, the depü of charnfering plus theroot penetrat¡on when specified).
5,f .2.2 The size of an equal-leg f¡llet weld shall be based on the leg lengü of the largest ¡sosceles right riangle thatcan be inscr¡bed wiü¡n the cross-section of the f¡llet weld. The size of an unequal-l€ f¡llet weld shall be based on the
\-. leg leng[hs of the largest right triangle that can be inscribed within üe cross-sect¡on of the f¡llet weld.
5-'l
API STaNDARo 650
5.1.3 Restrict¡ons on Jo¡nts
5.1.3.1 Restr¡ctions on the type and s¡ze of welded jo¡nts are g¡ven ¡n 5. t.3.2 through 5.1.3.8.
5.1.3.2 Tack welds shall not be cons¡dered as hav¡ng any strength value in üe f¡nished structure.
5.1.3.3 The m¡n¡mum size of fillet welds shall be as folloti,s: On plates 5 mm (3ho ¡n.) th¡ck, the weld shall be a full-f¡llet weld, and on plates more than 5 mm (3/16 in.) thick, the weld th¡ckness shall not be less than one-th¡rd thethickness of the th¡nner plate at thejo¡nt and shall be at least 5 mm (3h6 ¡n.).
5.1.3.4 Single-welded lap jo¡n6 are pemissible only on bottom plates and roof plates.
5.1.3.5 Lap-welded jo¡nts, as tack-welded, shall be lapped at least f¡ve times the nominal thickness of the h¡nnerplate joined; ho^rever, with double-welded lapjoints, the lap need not exceed 50 mm (2 in.), and with single-weldedlapjdnts, the lap need not exceed 25 mm ('l ¡n.).
5.1,3.6 Weld passes are resú¡cted as follows:
.5.I.3.6.1 For bottom date welds and roof plate welds for all materials, and for shell-to-bonom welds for Group6 l, ll,lll, and lllA materials, the following weld s¡ze requ¡rements apply:
a) For manual weld¡ng processes, fillet weld legs or groove weld depths greater than 6 mm (1h ¡n.) shall bemult¡pass, unless othen¡/¡se specif¡ed on the Data Sheet, L¡ne 15.
b) For sem¡-automaüc, machine, and automat¡c weld¡ng processes, with the except¡on for electrGgas welding in7.2.3.4, fillet weld legs or groove weld depths greater than 10 mm (3/s ¡n.) shall be multipass, unless othen¡vise aspec¡fied on the Data Sheet, Line 15.
5,1.3.6.2 For Groups lV lVA, V, or Vl shell-to-bottom welds for all weld¡ng processes, all welds shall be made us¡rEa m¡nimum of two passes.
5.1.3.7 Attachrnents to tank exterior surfaces shall be as follows.
a) Except as provided ¡n item b. below all attachments to tank elferior surfaces shall be completety seal welded (no¡ntermi[ent weld¡ng) to min¡mize rust streaking.
b) lf specif¡ed on the Data Sheel intermittent weld¡ng ¡s permmed for:
1) wind g¡rders as described ¡n 5.1.5.8;
2) attachments to surfaces that will be covered by insulat¡on;
3) attachments to sulaces of conosion-resistant materials, includ¡ng hjt not l¡mited to sta¡nless steel (See AnnexS and Annex X) and alum¡num (See Annex AL).
5.1.3.8 Except as permmed in 5.1.5.5 and 5.1.5.6, peflnanent weld jo¡nt backing súips are pemmed only with $eapproval of the Purchaser.
5.1.4 Weld¡ng Symbols
Welding symbols used on &awings shall be the symbo¡s of the American Welding Society.
WELoED TANKS FoR OrL SToRAGE
5.1.5 Typ¡cal Joints
5.1.5.1 General
a) Typical tankjo¡nts are shown ¡n F¡gure 5.1, F¡gure 5.2, F¡gure 5.3a, Figure 5.3b, and F¡gure 5.3c.
b) The top surfaces of bottom welds (bun-welded annular plates, bun-welded sketch plates, or F¡gure s.3bjoin6)shall be ground flush where they will contact the bonoms of the shell, insert plates, or reinforcing plates.
5.1.5.2 Vert¡cal Shell Joints
a) Vertical shelljoints shall be buttjo¡nts with complete penetrat¡on and complete fus¡on attained by double weldingor other means that w¡ll obtain the same quality of deposited weld metal on the inside and outside weld surfaces tomeet the requirements of 7.2.1 and 7 .?.3. The suitab¡lity of the plate preparat¡on and welding procedure shall bedeterm¡ned in accordance with 9.2.
b) Vertical jo¡nts ¡n adjacent shell courses shall not be aligned. but shall be offset from each other a minimumdistance of 5¿ where ¿¡s the plate th¡ckness of the thicker course at the point of offset.
Single-V butt joint
Single-U butt joint
Double-V butt joint
Square{roove butt joint
NOTE See 5.1.5.2 for spec¡fic requirements for vertical shefl io¡nts.
Double-U butt jo¡nt
F¡gure 5.1-Typ¡cal Vertical Shell Jo¡nts
5-4 API SfANDARD 650
Opt¡onaloutside angle
Alternativeangle-to-shell joint H
Squar+groovebutt joint-
complete penetrÍ¡t¡on
Angl+.tcshellbutt jo¡nt-
complete penetration
Singlqbevel Double-bevelbuttjoint- butt jo¡nt-
complete'penetration complete penetrat¡on
NOTE See 5.1.5 3 for specific requirements for horizontral shell ¡o¡nts'
F¡gure s.2-Typical Hor¡zontal Shell Jo¡nB
5.1.5.3 Hor¡zontal Shell Joints
a) Horizontal shelljoints shall have complete penetration and complete fus¡on; however, as an ahernative, top angles
may be attachá to the shell by a ciouble-welded lap joint. The suitability of üe pate preparaüon and welding
procedure shall be determined in accordance with 9.2.
b) Unless otheMise specif¡ed, abutting shell plates at horizontaljoints shall have a common vertical centerline.
5.1.5.4 Lapwelded Bottom Joints
5.1.5.4..t Lap-welded bonom plates shall be reasonably rectangular. Additionally, plate may be either square cut or
may have miliedges. Mill edge; to be welded shall be reiat¡vely smooth and uniform, free of deleterious depos'rts, and
naó a snape suÉh that "
fu'¡l fillet weld can be achieved. Uniess otherwise spec¡f¡ed by the Purchaser, lap welded
plrto on s't'op"d bottorr shall be oveflapped ¡n a manner to feduce the tendency for liquid to puddle dur¡ng draw-
down.
S.1.S.4.2 Three-plate laps in tank bottoms shall be at least 3OO mm (12 in.) from each other, from the tank shell, and
fiom¡oinS Uetwedn annu'lar plates and the bottom. A three-plate lap ¡s created where three plates come together and
.lr piát* "á"¡*o to one another by lap welds. A locat¡on where a pa¡r of bottom plates are lapwelded to each other
áná áre r"ppeO onto an annular páte tonstiurtes a three-plate tap, but tapping a s¡ngle bottom plate onto a butt-
*"fO"O unhilur plate splice does not constige a three-fláte hp weld s¡nce the two annular plates are not joined
¿é;th", bt ; hd *etd. ihese tapjoint connecüons ro the btrtt-weld annular plate are ¡llustrated in Figure 5.3d.
WELDED TAÑKS FOR OIL STORAGE
Roof-Plate Jo¡nt
t#;'t'ffiffiRoof-to-Shell Jo¡nts
lns¡de of shell
Altemative Roof -to-Shell Jo¡nt(See Note 2)
-'t 75t sR<3f
t
+
S¡ngle-welded butt jo¡ntw¡th backing strip
'r-\----rI l- lnside
Bottom or annular I I
bottom olate - I I
J-é-§Bottom-to§hell Jo¡nt
r 91131í!
=:ffit--------------- \R-Ta* weld
Sing¡e-weldedtull-fillet lap joint
Bottom'Plate Joints
NOTE 1 See 5.1.5.4 through 5.1.5.9 for spec¡fic requirements for roof and bottom jo¡nts
NOTE 2 The altemat¡ve roof-to-shell io¡nt ¡s subject to the l¡mitat¡oñs of 5.1.5 9' ltem f.
Figure s.3a-TyP¡cal Roof and Bottom Joints
API STANoARD 650
Figure s.3b-Method for Preparing Lap-welded Bottom plates under Tank Shell (See 5.1.5.4)
Shell plate
A=Bforup to 25 mm(1 in.) annularplate 45' m¡n¡mum
Annular bottom plate
13 mm (1/2 ¡n.) maximum6 mm (1/a in.) minimum
A + B m¡nimum
NOTE 1 A = Fillet weld size l¡mited to 13 mm (1/2 ¡n.) max¡mum.
NOTE 2 A + B = Th¡nner of shell or annular bottom plate thickness.
NOTE3 Groove weld B may exceed fillet s¡zeAonly when annular plate is thicker than 25 mm (1 in.).
Figure s.3c-Detail of Double F¡llet-groove Weld for Annular Bottom Plates with a Nom¡nal Th¡cknessGreater than 13 mm (r/z in.) (See 5. f .5.7, ltem b)
5.1.5.4.3 When annular plates are used or are required by 5.5.1, they shall be butt-welded and shall have a rad¡alwidth that provides at least 600 mm (24 in.) between the inside of the shell and any lap-weldedjoint in the rema¡nderof the bottom. Bottom plates need to be welded on the top side only, with a cont¡nuous full-f¡llet weld on all seams.Unless annular bottom plates are used, the bottom plates under the bottom shell ring shall have the outer ends of thejo¡nts frned and lap-welded to form a smooth bearing suface for the shell plates, as shown in Figure 5.3b. Lap-weldedbottom plates shall be seal-welded to each other on the exposed outer periphery of their lapped edges.
5-6
wELoED faNKS FoR Ot! SToRAGE 5-7
F¡gure 5.3d-SPac¡ng of fhree-Plate Welds at Annular Plates
5.1.5.5 Butt-Welded Bottom Joints
Bm-wdded bottom plates shall have the¡r parallel edges prepared for btrn welding with either Square or V grooves'
Butt-welds shall be made using an appropriate welj joi;t éonfiguration that yields a complete penetration weld'
Tvo¡cal oermissible bottom brm-welds wittrout a Uacking strip are the same as those shown in Figure 5 1 The use of
á'riiitiñg ruip át teast 3 mm (1/B ¡n.) rhick rack welded-to the underside of the plate is perm¡tted- Butt-welds using a
Oacking itrip are shown in F¡gure 53a. tf square grooves are employed, the root openings tY]1 "?,_!.
less than 6
mm 1r[ ,n.r' o .",u1 spacer s-ha[ be used to maináin üre root opeiring between the adjoining plate edges unless the
Manufactuier submits another rnethod of buü-weld¡ng the bottom for the Purchaser's aPproval Three-plate jo¡nts ¡n
üetankbonomshallbeatleast3oomm(12¡n.)fromeachotherandfromthetankShell.
Bottom plate
Bottom plate
lap joint- \
API SIANDARD 650
5.1,5.6 Bottom Annular-Plate Joints
Bonom annular-plate radial joints shall be butt-welded ¡n accordance with 5.1.5.5 and shall have completepenetration and complete fus¡on. The backing str¡p, ¡f used, shall be compat¡ble for welding the annular platestogether.
5.1.5.7 Shell-to-Bottom F¡llet Welds
a) For bottom and annular plates w¡th a nominal th¡ckness 13 mm (1/z in.), and less, the attachment between thebottom edge of the lowest course shell plate and the bottom plate shall be a continuous fillet weld la¡d on eachside of the shell plate. The size of each weld shall not be more than 13 mm (1/2 in.) and shall not be less than thenominal thickness of the th¡nner of the two plates joined (lhat is, the shell plate or the bottom plate immediatelyunder the shell) or less than the following values:
Nom¡nal Thickness of Shell plate M¡n¡mum S¡ze of F¡llet Weld
(mm) 0n.) (mm) (in.)
5 0.1875 5 3/16
> 5 to 20 > 0.1875 to 0.75 6 1la
> 20 fo 32 > 0.7S to 1.25 I s/16
>32to45 > 1,25101.75 10 3/s
b) For annular plates with a nom¡nal thickness greater than t 3 mm (1/2 ¡n.), the attachment welds shall be sized sothat either üe legs of the fillet welds or the groove depth plus the leg of the fillet for a combined weld is of a s¡ze .-.equal to the annular-Plate th¡ckness (see F¡gure 5.3c), but shall not exceed the shell plate thickness. \
c) Shell-tGbottom fillet weld around low-type re¡nforc¡ng pads shown in Figure 5.8 Details a and b or around shellinsert plates that extend beyond the outside suface of the adjacent tank shell shall be sized as required byparagraphsaorbabove.
d) The bonom or annular plates shall be suff¡cient to provide a minimum 13 mm (1/2 in.) from the toe of the f¡llet weldreferenced ¡n 5.1.5.7c to the ouBide edge of the bottom or annular plates.
5.1.5.8 Wind Girder Joints
a) Full-penetration butt-welds shall be used forjo¡n¡ng ring secüons.
' b) Continuous welds shall be used for all horizontal top-sidejo¡nb and for all venicaljo¡nts. Horizontal bottom-s¡dejo¡nts shall be seal-welded unless specified otherw¡se by the purchaser.
5.1.5.9 Roof and Top-Angle Jo¡nts
a) Roof plates shall, as a m¡n¡mum, be welded on the top side with a conünuous full-l¡llet weld on all seams. Butt-welds are also permitted.
b) For ftang¡ble roofs, roof plates shall be attached to the top angle of a tank with a cont¡nuous fillet weld on the topside only, as sp€cif¡ed in 5.10.2.6. For non-ftangible roofs, altemate deta¡ls are pem¡ned.
c) The top-angle secl¡ons, tens¡on r¡ngs, and compress¡on rirEs shall be joined by futt-welds having completepenetraüon and fusion. Joint eff¡c¡ency factors need not be applied when conform¡ng to the requ¡rements of 5.10.5and 5.10.6.
d) At the opüon of the Manufacturer, for self-supporting roofs of the cone, dome, or umbrella type, the edges of theroof plates may be flanged horizontally to rest flat aga¡nst the top angle to ¡mprove welding conditions.
WELoED TaNKS FoR OrL SToRAGE
. e) Except as specmed for open-top tanks in 5.9, for tanks w¡th frangible joints per5.10.2.6, for self-supporting roofs ¡n
5.10.5, and 5.10.6, and for tanks w¡th the flanged roof-to-shell detail described ¡n ltem f below tank shells shall besupplied with top angles of not less than the follow¡ng s¡zes:
Tank D¡ameter@
M¡n¡mum Top Angle S¡zea Minimum Top Angle S¡zea(mm) (¡n.)
D< 11 m, (D< 35 ft)
11 m< D<18m, (35ft<D<60ft)
D> 18 m, (D> 60fr)
50x50x550x50x675x75x10
2 x 2 x3116
2xZx111
3x3x3/g
a Approximate equ¡valent s¡zes may b€ used to accommodate ¡ocal ava¡lab¡lity of materials.
For fixed roof tanks equipped with full shell he¡ght ¡nsulation orjacket¡ng, the horizontal leg of the toP shell stiffener
shall project outward. Fof ¡nsulat¡on system compat¡b¡lity, the Purchaser shall specify if the horizontal leg ¡s to be
larger than specified above.
b) For tanks with a diameter less than or equalto 9 m (30 ft) and a supported cone roof (see 5.10.4), the top edge of
the shell may be flanged in l¡eu of installing a top angle. The bend radius and the w¡dth of the flanged edge shall
conform to tñe deta¡ls of Figure 5.3a. Th¡s construct¡on may be used for any tank with a self-supporting roof (see
5.10.5 and 5.10.6) if the total cross-sectional area of the junction fulf¡lls the stated area requ¡rements for the
construction of the top angle. No additional member, such as an angle or a bar, shall be added to üe flanged roof-
to-shelldetail.
5.2 DesignCons¡derat¡ons
5.2.1 Loads
Loads are def¡ned as follows.
a) Dead Load (O¿): The weight of the iank or tank component, including any conosion allowance unless otherw¡se
noted.
b) Design External Pressure (PJ: Shall not be less than 0.25 kPa ( l in. of water) except that Extemal Pressure (PJ
shall b€ cons¡dered as O kPa (O in. of water) for tanks with c¡rculaüon vents meeting Annex H requiremenE. Refer
to Annex V for external pressure greater than 0.25 kPa (1 in. of water). Design requiremenb for vacuum
exceeding this value and des¡gn requirements to resist flotation and extemal fluid pressure shall be a matter ofagreement between the Purchaser and the Manufacturer (see Annex V). Tanks that rn€et the requirenrents of th¡s
standard may be subjected to a partial vacuum of 0.25 kPa (1 in. of water). without the need to provide anyadditional supporting calculations.
c) Des¡gn lnternal Pressure (P): Shall not exceed 18 kPa (2.5 lbí¡n.2).
O Hydrostatic Test (¡4): The load due to f¡lling the tank with water to the des¡gn liquid level.
e) lnternal Floating Roof Loads:
1) Dmd load of ¡nternal floating roof (rri ¡ncluding the weight of the flotation compartments, seal and all otherfloating roof and attached components.
2) lnternal floaüng roof uniform live load (Z¿) (0.6 kPa [12.5 lbfft2D ¡f no automatic drains are provided, (O.24 kPa[5 lbflfz]) ¡f automat¡c drains are provided).
3) lnternal floating roof po¡nt load (¿z) of at least Nvo men walk¡ng anlMhere on the roof. One applied load ot 2.2kN [500 lbfl over 0.1 m2 [1 ft21 appl¡ed an]Nhere on the roof addresses two men walk¡ng.
4) lnternal floating roof design extemal pressure (Pr) of (O.24 kPa [5 |bflft2]) minimum.
f) Min¡mum Roof Live Load (¿): 1 .o kPa (20 Ib/fr2) on the horizontal prqiected area of the rmf. The m¡nimum roofl¡ve load may alternatively be determ¡ned in accordance with ASCE 7, but shall not be less than 0.72 kPa (15 pso.The minimum roof live load shall be reported to the Purchaser.
o g) Seismic (E): Seismic loads detem¡ned in accordance with E.l through E.6 (see Data Sheet, Line 8).
API STANoARD 650
. h) Snow (5): The ground snow load shall be detemined from ASCE 7, Figure 7-1 or Table 7l unless the ground snow- load that equals or exceeds the value based on a 2o/o annual probability of being exceeded (so-year rnean
recurrence ¡nterval) or a national standard (such as the National Bu¡lding Code of Canada) ¡s specified by thePurchaser.
1) The balanced des¡gn snow load (Sá) shall be 0.84 times the ground snow load. Alternately, the balanced design
snow load (Sá) shall be determined from the ground snow load in accordance w¡th ASCE 7. The balanceddes¡gn snow load shall be reported to the Purchaser.
2) The unbalanced design snow load (SJ for cone roofs with a slope of 10" or less shall be equal to the balancedsnow load. The unbalanced design snow load (SJ for all other roofs shall be 1.5 times the balanced designsnow load. Unbalanced design snow load shall be applied over a 135' sector of üe roof plan with no snow onthe rema¡ning 225' sector. Ahernately, the unbalanced snow load shall be determined from the ground snowload in accordance with ASCE 7
3) The balanced and unbalanced design snow loads shall be reported to the Purchaser.
. ¡) Stored Liquid (fl: The load due to filling the tank to the design liqu¡d level (see 5.6.3.2) with liquid with üe des¡gnspecific gravity specmed by the Purchaser.
j) Test Pressure (P): As requ¡red by F.4.4 or F.7.6.
k) Wind (Ifl: The des¡gn w¡nd speed (y) shall be either:
- the 3-sec gust design únd speed determ¡ned from ASCE 7-05 multipl¡ed by {¿ F¡gure 6-1; or
- the 3-sec gust design wind speed determ¡ned from ASCE 7-10 for r¡sk category specif¡ed by the Purchaser(Figure 26.5-1A, F¡gure 26.5-18, or Figure 26.5- lC) rrult¡pl¡ed by 0.78; or
- the 3-sec gust design wind speed specmed by the Purchaser, which shall be for a 3-sec Atlst based on a 2 %annual probab¡l¡ty of be¡ng exceeded lso-year mean recunence ¡ntervall.
The 3-sec gust wind speed used shall be reported to the Purchaser.
1) Design wind pressure (&/s and fi/vd using des¡gn wind speed (14: The design wind pressure on shell (Pws)
shall be 0.86 kPa (14190)2, (18 lbfn?,vlla0ll on venical projected areas of cy¡ndr¡cal surfaces. The designwind uplift pressure on roof (fup) shall be 1.44 kPa (I,4190)2, (f3O lbflftzllu1zo/l2) (see item 2) on horizontalprqected areas of conical or doubly curved sulaces. These design wind pressures are in accordance withASCE 7-05 for wind exposure Category C. As alternaüves, pressures may be determined in accordance with:
a) ASCE 7-05 (exposure category and importance factor provided by Purchaser); or
b) ASCE 7-10 (exposure category and risk category prov¡ded by Purchaser) wiü either velocity multiplied by0.78 or the ASCE 7-10 pressure multiplied by 0.6; or
c) a national standard for üe specif¡c conditions for the tank be¡ng designed.
2) The design uplift pressure on the roof (wind plus internal pressure) need not exceed 1.6 times the designpressure P determ¡ned ¡n F.4.1.
3) Windward and leeward horizontal wind loads on üe roof are conservatively equal and opposite and thereforethey are not ¡ncluded in the above pressures.
4) Fastest mile wind speed ümes 1.2 is approx¡mately equal to 3-sec gust wind speed (14
I NOTE ASCE 7-10 wind velocities now have LRFD load faclors and rhk category (importance faclors) bu¡h ¡n. whereas API
I 650 uses the work¡nq stess. The 0.78 factor appl¡ed to the ASCE 7-10 wind speed prov¡des a conveEion to working súess
I levels.
5-10
WEI DFD TaNKs aoR OtL SToRAGE
\/ . l) Extemal Loads:
. 1) The Purchaser shall state the magn¡tJde and d¡rection of extemal loads or restraint, if any, for wh¡ch the shell orshell connections must be des¡gned. The design for such loadings shall be a matter of agreement between thePurchaser and üe Manufa cturer.
. 2) Unless otheMise specified, seism¡c des¡gn shall be in accordance with Annex E.
o 3) Design for local¡zed wind induced forces on roof components shall be a matter of agreement between thePurchaser and the Manufacfurer.
4) Localized loads resulting from items such as ladders, stai6, plaúorms, etc., shall be cons¡dered.
5) The Purchaser shall siate the magnitude and d¡recüon of any external loads other than normal personnelaccess for wh¡ch the roof manholes and openings shall be designed. The design for sr.rch loadings shall be amatter of agreement between the Purchaser and the Manufacürer.
5.2.2 LoadComb¡nations
Loads shall be comb¡ned as follows. Design rules in this §andard use these load combinaüons, ¡nclud¡ng theabsence of any load other than D¿ in the combinations:
a) Flu¡d and lntemal Pressure: D¡+ F + P¡
b) Hydrostatic Test: D¡+ H¡+ P¡
c) Wind and lntemal Pressure: D¡+ W + F, P¡
\-, O W¡nd and Extemal Pressure: D¡+ W+0.4 P"
e) Gravity Loads:
1) D¡+ (L,or Sror Sf + 0.4 P"
2l D¡+ P"+O.A(Lror Sror 5¡)
0 Seismic: D¡+ F + E + 0.156+ Fo P¡
g) Gravity Loads for F¡xed Roofs with Suspended Floaüng Roofs:
1l D¿+ D¡+ (Lror S) + P"+ 0-4(p¡"or Lxor L¡)
2l DL + D¡+ (P¡"or Lx or L¡) + 0.4[(Z,or 5) + PJ
' The pressure combination factor (Fy' is defined as the ratio of normal operat¡ng pressure to des¡gn pressure, with am¡nimum value of 0.4.
5.2.3 Des¡gn Factors
' The Purchaser shall state th9 des¡gn metal temperature (based on ambient temperatures), the maximum designtemperature, the design specific gravity, the conosion allowance (if any), and the seismic factors.
5-1',l
. 5.2.4 Protect¡ve Measures
The Purchaser shall cons¡der foundations, corosion allowance, hardness testing, and any other protective measuresdeemed necessary. For example, for insulated tanks, rneans to prevent inliltraüon of watá ¡nto the ¡nsulation shall be
\- specif¡ed, espec¡ally around penetrations of the ¡nsulat¡on and at the roof-to-shelljunction.
5-12
5.2.5 Tank Capacity
5.2.5.1 The Purchaser shall specify the maximum capacity and tlle overf¡ll protection level (or volume) requ¡rement
(see API 2350).
5.2.5.2 Max¡mum capac¡ty is the volume of product ¡n a tank when the tank is f¡lled to its design l¡quid level as
defined ¡n 5.6.3.2 (see F¡gure 5.4).
5.2.5.3 The net work¡rE capacity is the volume of available product under normal operating condiüons. The net
work¡ng capacity is equafto the maximum capacity (see 5.2.6.2) less the minimum operating volurne rema¡n¡ng ¡n the
tank, less the overfill protect¡on level (or volume) requirement (see Figure 5.4).
5.3 SpecialConsiderat¡ons
5.3.1 Foundation
5.3.1.1 The selection of the tank site and the design and construction of the foundaüon shall be given careful
consideration, as ouüined in Annex B, to ensure adequate tank support. The adequacy of the foundation is the
responsibil§ of the Purchaser. Foundation loading data shall be provided by the Manufaclurer on the Data sheet,
L¡ne 13.
S.3..t .2 Sl¡d¡ng frict¡on res¡stance shall be verif¡ed for tanks subject to lateral w¡nd loads or se¡sm¡c loads (see 5 . 1 1 .4
and E.7.6).
5.3.2 CorosionAllowances
5.3.2.1 The purchaser, after gMng cons¡deraüon to the total eflect cf the l¡quid stored, ¡he vapor. above the liqu¡d,
and the atmospheric environmént, ahall specify ¡n the Data Sheet, Table 1 and Table 2, any coros¡on allou,ances to
be prov¡ded for all componens, including eacñ shell course, for the bottom, for the roof, for nozzles and manholes,
and for structural members.
Overf¡ll slotToo of shell he¡oht
Des¡gn liqu¡d level
Normal fill level
Net working capacity:
m3 (bbr)
M¡nimum f¡ll level
API STANDARO 650
I
ll
-T--I
I
Maximum capa
-m3(I
-]-
m3 lbbt¡ or mm (¡n-)
Overflll protection level requ¡rement:
-
m3 (bbl) or
--
mm (in.)
Figure 5.4-Storage Tank
Top of bottom plate at shell
W€LDED TaNKs FoR O[ SToMGE 5-13
5.3.2.2 Exclud¡ng nozzle necks, corros¡on allowances for nozzles, flush-type cleanouts, manholes, and self-supporting roofs shall be added to the design th¡ckness, ¡f calculated, or to the m¡nimum spec¡fied thickness.
5.3.2,3 For nozzle necks, any specif¡ed nozzle neck coros¡on allowance shall, by agreement between thePurchaser and the Manufacturer, be added to e¡ther the nominal neck thickness shown ¡n Table 5.6a and Table 5.6b(or Table 5.7a and Table 5.7b), or to the min¡mum calculated th¡ckness required for pressure head and mechanicalstrength. ln no case shall the neck th¡ckness prov¡ded be less than the nominal th¡ckness shown ¡n the table.
5.3.2.4 Corros¡on allowance for anchor bolts shall be added to üe nominal diameter.
5.3.2.5 Conosion allowance for anchor straps and brackets shall be added to the required sEap and bracketthickness.
5.3.2.6 For intemal sEuctJral rnembers, the conosion allowance shall be applied to üle total thickness unlessotheM¡se specif¡ed.
5.3.3 Serv¡ceCondit¡ons
The Purchaser shall specify any applicable special metallurgical requirements pertain¡ng to the selection of materialsand the fabrication processes as requ¡red by any antcipated service condit¡ons. When the service conditions might¡nclude the presence of hydrogen sulfide or other conditions that could promote hydrogen-¡nduced cracking, notablynear the bonom of the shell at the shell-to-bonom connect¡ons, care should be taken to ensure that the materials ofüe tank and details of construct¡on are adequate to resist hydrogen-¡nduced crack¡ng. The Purchaser shouldconsider limits on the sulfur content ofthe base and weld rnetals as well as appropr¡ate quality control procedures inplate and üank fabricat¡on. The hardness of the welds, includ¡ng the heat-affected zones, in contact with theseconditions should be considered. The weld meial and adjacent heat-affected zone often contain a zone of hardnesswell ¡n excess of Rockwell C 22 and can be expected to be more susceptible to cracking than unwelded metal ¡s. Anyhardness criter¡a should be a matter of agreement between the Purchaser and the Manufacturer and should bebased on an evaluation of the expected hydrogen sumde concentration in the product, the possib¡l¡ty of moisurebe¡ng present on üe inside metal suface, and the strenqü and hardness characterist¡cs of the base metal and weldmetal. See the Data Sheet, L¡ne 5.
5.3.4 Weld Hardness
a) Weld metal and Heat Affected Zone (HAZ) hardnesses shall comply wiü the H2S Supplemental Spec¡f¡cationlisted on the Data Sheet, L¡ne 5, when specmed by the Purchaser.
b) When spec¡f¡ed by ihe Purchaser, the hardness of the weld metal for shell materials in Group lV, lVA, V or Vl shallbe evaluated by one or both of the follow¡ng methods.
'l ) The welding-procedure qualificat¡on tests for all weld¡ng shall include hardness tess of the weld metal and heat-affected zone of the test plate. The methods of test¡ng and the acceptance standards shall be agreed upon bythe Purchaser and the Mandacturer.
2) All welds depos¡ted by machine or an automaüc process shall be hardness tested on the prodrct-side surface.Unless otherw¡se specified, one test shall be conducted for each venical weld, and one test shall be conductedfor each 30 m (10o ft) of circumferential weld. The methods of tesüng and the acceptance standards shall beagreed upon by the Purchaser and the Manufacturer.
5.3.5 Thickness
When 6 mm (1/a in.) thick mater¡al is specif¡ed, 0.236 in. th¡ck material may be used in the US Customary rule set withPurchaser approval. Sim¡larly when 5 mm (3¡6 ¡n.) thick rnaterial ¡s specif¡ed, 4.8 mm. thick material máy be used inthe Sl rule set with Purchaser approval. The des¡gn calculat¡ons shall be based on thickness used.
5.14 API SIANDARD 650
5.4 Bottom Plates
S.4.1 All botom plates shall have a conoded thickness of not less than 6 mm (0.236 ¡n.) [49.8 kg/m2 (9.6 lbfift2) (see
4.2.t.2)1. Unless otfErwise agreed to by the Purchaser, allrectangular and sketch plates (bottom plates on which the
shell rests that have one end rectangular) shall have a nom¡nal width of not less üan 1800 mm (72 ¡n.).
S.¡t.2 Bottom plates of suffic¡ent s¡ze shall be ordered so that, when trimmed, at least a 50 mm (2 ¡n.) width will
Foject ou6¡de the shell or meet requ¡rements given ¡n 5.1.5.7 d whichever is greater.
5.4.3 Bottom plates shall be welded in accordance with 5.1.5.4 or 5.1.5.5.
5.4.4 Unless otherw¡se specif¡ed on the Data Sheet, Line 12, tank bottoms requiring sloping shall have a minimum
slope of 1 :120 upwards toward center of the tank.
S.4,5 tf specified on the Data Sheet, Line 12, a foundation drip ring shall be provided to prevent ingress of
water between the tank bottom and foundation. Unless the Purchaser spec¡fies otherwise, the r¡ng shall meet
the follow¡ng requirements (see Figure 5.5)..
1) Material shall be carbon steel, 3 mm (1/8 in.) m¡nimum th¡ckness.
2) A[ radialjoins beNveen sect¡ons of the dr¡p rings, as well as between the drip ring and the annular plate or
bottom, shall be cont¡nuously seal-welded.
3) The drip ring shall extend at least 75 mm (3 ¡n.) beyond the outer periphery of the foundat¡on ringwall and then
turn down (up to 90") at its outer diameter.
4) The top and bottom of the drip ring, and the top of the tank bottom edge projection beyond the shell, and a
portion of the tank shell shall be coated if sPec¡f¡ed by the Purchaser.
F¡gure s.s-Drip Ring (Suggested Detail)
WEToED faNKs FoR OrL SToRAGE 5,15
5.5 Annular Bottom Plates
5.5.1 When the bottom shell course ¡s des¡gned us¡ng üe allowable stress for mater¡als ¡n Group lV, lVA, V, or Vl,bun-welded annular bottom plates shall be used (see 5.1.5.6). When the bottom shell corrse ¡s of a material ¡n GrouplV, lVA, V or Vl and tlle max¡mum produd sress (see 5.6.2.1) for the f¡rst shell course is less than or equal to 160MPa (23,200 lbf/in.2) or the max¡mum hydrostatic test stress (see 5.6.2.2) for üe f¡rst shell course is less than orequal to 171 MPa (24,900 lbflin.2), lapwelded bonom plates (see 5.1.5.4) may be used ¡n l¡eu of hm-wdded annularbottom plates.
5.5.2 Annular bonom plates shall have a radial width that proúdes at least 600 mm (24 in.) between the inside of theshell and any lap-welded jo¡nt ¡n the rema¡nder of the bottom. Annular bonom plate project¡on ou6¡de the shell shallmeet the requirements of 5.4.2. A greater radial w¡dth of annular plate ¡s requ¡red when calculated as follo^,s:
ln Sl units:
?t5 tb
(HC\ou
where
fá ¡s the th¡ckness of the annular plate (see 5.5.3), ¡n mm;
i/ is the maximum design l¡qu¡d level (see 5.6.3.2), ¡n m;
G ¡s the des¡gn specif¡c gravity of the liquid to be stored.
ln USC units:
390 rá
(HG)ou
where
¡s the th¡ckness of the annular plate (see 5.5.3), ¡n ¡nches;
¡s the max¡mum des¡gn l¡qu¡d level (see 5.6.3.2), in feet;
is the design specmc aravity of the l¡gu¡d to be stored.
t¡
H
5.5.3 The thickness of the annular bouom plates shall not be less than the greater th¡ckness determ¡ned us¡ng Table5.1a and Table 5.lb for producl des¡gn (plus any specmed cofiosion allowance) or for hydrostat¡c test des¡gn. Table5.1a and Table 5.1b are applicable for effective product height of ¡lx C<?3 ñ (75 ft). Beyond this height an elast¡canal)§is must be made to determine the annular plate thickness.
5.5.4 The ring of annular plates shall have a circular outs¡de circumference, hf may have a regular polygonalshape ¡ns¡de the tank shell, with the number of sides equal to the number of annular Pates. These p¡eces shall bewelded in accordance w¡th 5.1.5.6 and 5.1.5.7, ltem b.
5.5.5 ln l¡eu of annular plates, the entire bottom may be butt-welded provided that the requ¡rements for annular plateth¡ckness, welding, mater¡als, and inspect¡on are met for the annular d¡stance specif¡ed ¡n S.S.2.
5-16 \ --, API STANDARD 650
Table 5.1a-Annular Bottom-Plate Thicknesses (rd (Sl)
Plate Th¡cknessa of F¡rstshell Course
(mm)
Stressb in First Shell Course (MPa)
s 190 < 2'lo <220 < 250
¿< 19 6 6 7 I
]9 < ,< 25 6 7 l0 lt
25 < t<32 6 9 12 l4
32< t<40 8 11 l4 ),7
40< t< 45 I '13 l6 I9
á plate ü¡ckness refers to the cfioded shell plate thickness for prodEt des¡gn and nominal lh¡cktEss for hydrostatic tes(
derún.
b Iüe stress to be used h the ríax¡mum stress ¡n the frsl shell coi¡se (greater of pfodt¡cl or hydrolaüc tel sfess). The
$ress may be determined us¡ng the required hickness divkled by üle thick¡ess frorn'a'flen rruhiplied by the appli:auealbwabb súess:
Produd Súess = (rd - c/4/ cofioded r ) (sJ
Hydrosratic Test §ress = (f, / nominal r ) (S)
NOTE Tt|e úticknesses sDecned in úle l,able, as úell as üE widÚl soecified ¡n 5.5.2, are based oo the foufidatilo p.oüdingunifom s¡Jooort under |he hll widdl of ühe annt¡a date. Unle§s üé foundatixr is p.operly coíipacted, patÉJhrly at lheins¡de of a iixrcrete ringwall, sedemerü will Foduce additional sresses in Úle anrular plate.
Table 5.1b-Annular Bottom-Plate Thicknesses (r, (USC)
Plate Th¡cknessa of F¡rstShell Course
0nJ
stressb ¡n F¡rsl Shetl course 0bíin.2)
< 27,000 < 30,000 < 32,000 < 36,q)o
Í< 0.75 0.236 0.236 9llz 11llz
0.75<f<1.@ 0.236 9lzz 3/s lltt
1.00 < r< '1.25 0.236 ,rl:p 15lzz | g/re
1.25 < f< 1.50 J/15 7ha 9/rs llhe
1.50 < f< 1.75 11lzz 1lz s/8 3lq
a plate üil(ness refers to üe coÍoded shell date ttúloess for prod[t des¡gn and nominal th¡ckness fo. hydrolatic tes¡
de:¡go.
b fhe sress to be used is t le maximum sress ¡n ttle trsl st|ell corrse (greater of producl or trydro§atic tes¡ sress). The
sress rnay be dercrmined using tt¡e required thickness diviled by üe úúck¡ess frorn'a'üeí rrultid¡ed by üe apdi:able
allowaue stress:
Frodt¡d Sress = (fd - CAl co.roded I ) (Sd
Hydroslatic Tesl Suess = k¡ / rnminal r ) (SJ
NoTE TtE rhhknesses soeciñed in d1e table, as urell as Úle widü speciñed in 5.5.2, a.e based on lhe foondalbn proüding
;lio;" ;ñü-dü;-rü-r,,ti'ii¿Ur'-- ot trááñirular ptaie. Unless úÉ roundalixr is pr_op€rly coÍpacled. paticulaúy at üe#ñ otá¡ánciáa rngrxall, sedemern will Foduce ádditimal sres§es ¡n the annlar plate'
WEIDEo TAN(S FoR Ort SToRAGE 5-17
5.6 Shell Des¡gn
5.6.1 General
5.6.1.1 The requ¡red shell th¡ckness shall be the greater of the des¡gn shell th¡ckness, including any coÍosion
allowance, or tfe hydrostatic test shell th¡ckness, but the shell th¡ckness shall not be less than the following:
Nominal Tank Diameter Nominal Plate Thickness
< 15
15to<3636 to 60
>60
<50
50 to < 120
120 to 2m>2@
(mm)
5
6
8
10
(in.)(ft)(m)
lltJ/16
3lB
NOTE 1 Unless otherwise specif¡ed by ñe Púchaser, the mminaltank d¡amáef st¡all be Úe centedine d¡ametef of lfle bonom
shell-cotrse plates.
NOTE 2 The ühkness€s specified e based on erecl,on requ¡rernents.
NOTE 3 Vúhen sp€cmed by ü|e Purchaser, plate wiÚl a nom¡nal hkkness of 6 mm Í¡ay be subsü'nned for r/1-¡n. plale.
NOTE 4 For d¡aÍierefs less ú|an 15 m (5O ft) bú greater üan 3.2 m (10.5 ft), úte rlom¡nal tlickness of the lou,es¡ shell couseshall not be less ú|an 6 mm (rk ¡n.).
5.6.1.2 Unless otherw¡se agreed to by the Purchaser, the shell plates shall have a m¡nimum nom¡nal w¡dth of 1800
mm (72 in.). Plates that are to be hrtt-welded shall be properly squared.
5.6.1.3 The calculated stress for each shell course shall not be greater than the stress pemined for the particular
material used for the course. When ü1e allowable stress for an upper shell co¡rse ¡s lower than the allowable stress of
the next lower shell course, then either a or b shall be saüsfed.
a) The lower shell course thickness shall be no less than the thickness required of the upPr shell course for producl
and hydrostat¡c test loads by 5.6.3 or 5.6.4.
b) The th¡ckness of all shell courses shall be that detem¡ned from anthicknesses.
The ins¡de of an upper shell course shall not project beyond the ¡nside
within tolerances provided ¡n 7.2.3.2).
elastic analysis per 5.6.5 us¡ng final plate
surface of the shell course below (except
5.6.1./t The tank shell shall be checked for stab¡lity aga¡nst buckl¡ng faom the design w¡nd speed in accordance with5.9.7. lf requ¡red for süability, intermed¡ate girders, ¡ncreased shell-plate th¡cknesses, or both shall be used.
5.6.1.5 lsolated radial loads on the tank shell, such as those caused by heavy loads on plaÚorms and elevatedwalkways between tanks, shall be disributed by rolled structural sections, plate ribs, or bu¡lt-up members.
5.6.2 Allowable Stress
5.6.2.1 The max¡mum allowable product design stress, Sd, shall be as shown ¡n Table 5.2a and Table 5.2b. Theconoded plate th¡cknesses shall be used ¡n the calculat¡on. The design stress basis, Sd, shall be either two-thirds theyield strengúh or two-fifths the tens¡le strength, wh¡chever is less.
5.6.2.2 The max¡mum allowable hydrostaüc test stress, Sr, shall be as shown in Table 5.2a and Table 5.2b. The. nominal plate thicknesses shall be used in the calculat¡on. The hydrostaüc test basis shall be either threejounhs the\- yield srengrth or three-sevenths the tens¡le súength, wh¡chever is less.
5,18 API SfANoARo 650
Table 5.2a-Perm¡ss¡ble Plate Materials and Allowable Stresses (Sl)
PlateSpec¡f¡caüon Grade
Nom¡nal Plate M¡n¡mumfh¡ckness I Yield Strengü
mm MPa
M¡nimumTens¡le Sren$h
MPa
ProdrrctOes¡gn Stress Sd
MPa
HydrostaticTest Stress §
MPa
ASTM Specif¡cations
4283M C 20s 380 137 154
4285M C 205 380 '137 '154
4131M A,B 4m 151 171
A36M 2so 400 160 '17'l
4131M EH 36 360 490É 196 210
4573M 400 220 400 147 165
A573M 450 240 450 160 '180
A573M 485 2 4854 193 208
4516M 380 205 380 137 154
4516M 4'l 5 220 415 141 tb5
4516M 450 240 450 160 180
A516M 485 2ñ 485 173 195
4662t\,t B 215 450 180 193
4662M C 295 4854 194 208
A537M,] r< 65
65<t<1@
345
310
485¿
450b
194
180
208
193
4537¡il 2f< 65
65<f<1@
415
380
55@
515b
220
206
236
221
A633M C,D¡< 65
65 < f< 100
345
315
4854
450b
194
180
208
193
A678M 345 4854 194 208
4678M B 415 5504 220 236
4737M B 345 4B5a 194 208
A841M Class 1 345 4854 194 208
4841M Class 2 415 5504 220 236
WETDEo TAN(S FoR OIL STORAGE 5-19
fable 5.2a-Perm¡ssible Plate Mater¡als and Allowable Súesses (Sl) (Conünued)
PlateSpec¡ficat¡on
GradeNom¡nal PlaleThickness f
mm
M¡nimumY¡eld Strength
MPa
MinimumTens¡le Strenglh
MPa
ProductDes¡gn Súess Sd
MPa
Hydrostatic,fest Stess 5;
MPa
CSA Specif¡cat¡ons
G40.21M 260W 260 410 164 176
G40.21M 260 WT 260 410 164 176
G40.2rM 300w 3m 450 180 193
G40.21M 300wf 300 450 180 193
G40.21M 350W 350 450 180 193
G40.21M 35OWT1< 65
65<1<1@
350
320
48@
4804
'192
192
206
206
National Standards
235 235 365 137 154
250 250 400 157 111
275 275 430 167 't 84
ISO Spec¡l¡cat¡ons
tso 630E275C, D f< 16
16<¡<40
215
265
410
410
164
164
176
176
E355C, D
f s'16
16<f<40
40< f< 50
355
345
335
4904
4904
4904
196
196
196
2',lo
210
210
EN Specif¡cat¡ons
FN 10025 s 275J0,J2
f < 16
16 < t< 1112
275
265
410
410
164
164
176
176
s 355J0,J2, K2
¿< 16
16<f<40
40< f< 50
355
345
335
470á
47oá
110á
188
188
188
201
201
201
By agreernent be¡¡reen the Archaser aod the Manufacturer, üe tens¡le srengü of ASTM A537M, class 2, A678M, Grade B, and A8,l1M,Chss 2 Íiaterials may be increased to 585 MPa minimum and 590 MPa max¡rrlrm. The lens¡le súengü of úle oúler l¡sted materials may beincfeased to 515 MPa m¡nirrum and 620 MPa maximum. wlren th¡s is doÍ¡e, üe allormble súesses shall be delem¡ned as §ated in 5.6.2.1
añ5.6.2.2.
By ageement betu/een ttre Prrchaser and fie i¡tandacn er, ü¡e tensile strenglh ol ASTM A537M. Class 2 mate.ials may be irseased to550 MPa m¡n¡mum and 690 MPa rEx¡mum. The tens¡h srength of lhe other lisfed materials may be ¡ncreased to ,t85 MPa m¡n¡mum and620 MPa max¡mrm. whe¡ tfis ¡s doíe, the allo$,able sesses s¡lall be determined as süled ¡n 5.6.2.1 and 5.6.2.2.
API STANDARD 650
Table 5.2b-Permissible Plate Materials and Allowable Stresses (USC)
PlateSp€cificat¡on Grade
om¡nal PlateTh¡ckness ¡
in.
Min¡mumYield stren$h
Pst
M¡n¡mumTensile Strengfh
psl
ProdrctDes¡gn Stress Sd
Pst
Hvdfostaücteét Stress g
p§t
ASTM Specif¡caüons
4283 c 30,000 55,000 20,000 22,5ú
4285 C 30,000 55,000 20,000 22,5ú
413',] A,B 34,000 58,m0 22,1@ 24,900
436 36,000 58,000 23,2ú 24, O
A'131 EH 36 51,000 71,0004 28,400 30,400
4573 5B 32,000 58,000 21,300 24,000
4573 65 35,000 65,0m 23,3m 26,300
4573 70 42,000 70,m@ 28,000 30,000
4516 55 30,000 55,000 20.0o0 22,5@
A5r6 60 32,000 60,m0 21,3m 24,W
4516 65 35,000 6s,000 23,300 26,3m
A516 70 38,m0 70,000 25,3m 28,500
A662 B 40,000 65,000 26,000 21,9ú
4662 C 43.000 70,0@ 28,OOO 30.m0
A537,]
t < 2112
21lz < ts 4
50,000
45,@O
70,m@
65,mob
28,mO
26,000
30,m0
27,W
4537 2t < 21lz
2112 < t<460,000
55,mO
80.m@
75,mob
32,@O
30,0@
34,3@
32,1ú
4633 C,Dt < 2112
2112<t<4
50,000
46.mO
70.m@
65,mob
28,m0
26,000
30,mo
27,W
4678 50.000 70.00@ 28,000 30,000
4678 B 60,000 80,000¿ 32,000 34,3m
A7 37 B 50,000 70.m0¿ 28,000 30,000
A841 Class 1 s0,000 70.m0É 28,000 30.000
AB41 Class 2 60.000 80,m0É 32,000 34,3m
5-20
WELD€o TANKS FOR O[ SÍORAGE 5-21
Table 5.2b-Permiss¡ble Plate Mater¡als and Allowable Stresses (USc) (Cont¡nued)
PlateSpec¡f¡cation
Gradef{ominal PlaléTh¡ckness ,
¡n.
Min¡mumYield Strengnh
Psr
M¡nimumTensile Strcnglh
p§r
Product Hvdrostat¡cDesign Stress Sd Teét Stress.tps¡ Psr
CSA Spec¡ficat¡ons
G40.21 38W 38,000 60,000 24,OOO I zs,zm
G40.21 38WT 38,m0 60,000 24,W I 2s,7oo
G40.21 44,000 65,000 26,000 27,900
G40.21 44WT 44.000 65.000 26,000 I 27,s00
G40.21 50w 50,000 65,000 26,000 27,W
G40.2'l 5OWTG21lz
2112 < t<4
50,0m
46,000
70,m@
70,00@
28,m I *.00o
28,0m 30,000
Nat¡onal Siandards
235 34,000 52,600 20,000 22,5ú
250 36,000 58,300 22,7@ 25,mO
275 40,000 62,600 24,ffi 26,800
ISO Speciñcations
rso 630 E215C. D¡< 5/g
5lB < ts 1112
39,900
38,4m
59,500
59,500
23,800 25,500
23,8m 25,500
E355C. D
f< s/g
5lo < t<1112
1112 < t<2
51,5m
50,m0
48,600
71,00@
71,0004
71,moa
2A,4@ 30,4@
28,4ú 30,4m
28,4m 30,4m
EN Specificat¡ons
EN 10025s 275J0,
)2f< 5/g
5lB < t< 1112
39,9@
38,4m
s9,500
59,500
23,800 25,500
23,8m 2s,500
s 355J0, J2,K2
tssle5ls < t< 11lz
1112 < t<2
51,5m
50,000
48.600
68,10e
68,10@
68,10@
21,2ú 29,2ú
27,2ú 29,2@
27,2@ i zg.zm
By agreernent betveeen the Purchaser and úe Mandactrer, ú|e tem¡le sreogfi of ASTM A537M, class 2, A678M, Grade B, and A8'11M.
Ciasi Z materiats may be ¡rEreased to 85,OOO p6¡ min¡mum and 1 m,OOO É max¡mum. The te¡sile sEeogth cÍ the ott¡er l¡sted materials rnay
be increased to 75,ú p6¡ miniÍum and 9O,OOO ps¡ maximum. When this ¡s done, the allowable s¡resses shall be deiemined as stiated ¡n
5.6.2.1 and 5.6.2.2.
By agreerñent be eeo üle purchaser ard üe Manrracturer, th€ tens¡le süengü of ASTM A537M, Class 2 rnaierials may be ¡ncreased to
aO,Oú psi ninimum and 1m.OO0 ps¡ maimum. The terEfe sreígth of ltte oüler l¡led materials may be ¡rrcteased to 70,000 p§¡ rninimum
and 9O,OOO p6i mairrum. when Úl¡s is done, the allowable sesses shall be detemir¡ed as stated in 5.6.2.1 and 5.6.2.2.
API STaNDARD 650
5,6,2.3 Annex A pemits an alternaüve shell desiln wih a f¡xed allowable súess of 145 MPa (21,m0 bíin.2) and aio¡nt etrcjency faclor of 0.85 or 0.70. This des¡gn may onty be used for tanks with shell thicknesses less than or equal to13 mm (1/2 in.).
5.6.2.4 Structural design stresses shall confom to lhe allowable working stresses g¡ven in S.l O.3.
5.6.3 Calculation of Thickness by the l-Foot Method
5.6.3.1 The 1-foot method calculates the th¡cknesses requ¡red at des¡gn points 0.3 m ('l ft) above the bottom of eachshell course. Annex A permits only this design method. Th¡s method shall not be used for tanks larger than 61 m(2m ft) in diameter.
o 5.6.3.2 The requ¡red m¡n¡rum thickness of shell plates shall be the greater of the values comMed by the followingformulas:
ln Sl uniE:
4.9üH-0.3\G ^.I.= ____-+ + a-A'5;
. 4.9D(¡1- 0.3),,= ___T_
where
ro, ¡s the des¡gn shell th¡ckness, in mm;
fi h the hydrostatic test shell th¡ckness, ¡n mm;
D ¡s the norninal tank d¡ameter, ¡n m (see 5.6.'1.'1, Note 1);
. H is the desEn liqu¡d level, in m;
= heEht from the bottom of the course under cons¡deratbn to the top of üe shell including the top angle, ifany; lo ttle bottom of any overflotfl that l¡mits the tank f¡lling height; or to any other level specified by thePurchaser, resúicted by an ¡ntemal floating roof, or controlled to alloi/ for se¡smic wave action;
. G ¡s the design specific Aravity of the l¡quid to be stored, as specif¡ed by the Purchaser;
. CA is the conosion allotrrarre, ¡n rm, as specif¡ed by the Purchaser (see 5.3.2);
S¿ is the allowable stress for the des¡gn condition, in MPa (see 5.6.2.1);
.t ¡s the allowable súess for the hydrostat¡c test condition, in MPa (see 5.6.2.2).
ln USC units:
,,=2JA{)9*ct
2.6D(H-llt
API SrANoaRo 650
Table 5.la-Annular Bottom.Plate Thicknssses (1á) (Sl)
Plate Thlckne3s. of FirstShsll CouEe
(mm)
St¡ossb ¡n F¡rst Shell Course (MPa)
< 190 < 210 < 220 < 250
,< 19 6 6 1 9
'19</<25 6 7 l0 ll
25<t<32 6 I t2 l4
32<t<40 8 1l t,r t7
40<t<45 9 13 I6 l9
' Plab thbkness fshfs b ür€ conoded shel plale ürck,l€ss 6r prcdud dqign a¡d nom¡nal thil(n€ss 6r hydrcdatib bstdes¡gn,
b Th€ EüÉ33 b b6 us€d ¡s iho msximum st€ss ln th€ fi.§t st|el cor¡E€ (gBat€r of prcduct or Mrosiaüc tesl stB§s). Th€stB§s may be úete,mln€d ushg the r€qu¡r€d th¡d(,less divirsd by ü€ hlckn€ss fom 'a' üen multid¡od by ü|g apdlcatl€alo{rabl9 §UE6s:
Produd Stess = «r¿ - Cry coíoded , ) (sd)
tlydrc€btic Ted SüBss = (r, / no.n¡nal ¡ ) (S,)
NOTE Th€ 0lkj(¡6Es€s s9€ciñ€d h the tabb. as w9l as üle widh sD€o'ñed h 5.5.2. ar€ bas€d on the foi.rndaliro o.ovir¡nounibrm support undor the ful wtfh ol üle annuhr Dhb. Unless tho h¡ndatbn ¡s oroo€rlv cor5aded. Dafid¡leiiv et OÉ¡nskls ofa concrsE.irlgüa¡, sstthrner w¡lpreduce fuilbod sü€ss€s ¡n he annulai p}áb.'
Tablo 5.1b-Annular Bottom-Plate Thicknesses (¿) (USC)
Plate Thicknoss. of F¡ÉtSholl CouEe
(¡nJ
Strg3sb ¡n F¡rst Sholl Courss (lbf/¡n.2)
< 27,000 < 30,000 < 32,000 < 36,000
, < 0.75 0.236 0.236 9ltz 11lzz
0.75<r<1.00 0.236 9ltz 3/E 7lrs
1.00<r<1.25 0.236 11lzz 15lsz 9/r s
1.25<r<1.50 J/t6 7ha 9/r s 11lre
1.50 <, <'t.75 11b2 112 5lB
a Plab tliJ(¡6§§ rBErs b th6 conoded she¡ date t úd(n€ss br prodr¡d &s¡gn and ¡Em¡nal thijst€ss bi hydrostatic bstdes¡i¡n.
! The stBss b b€ ug€d § th€ maximum stBss ¡n üt9 frst sh€l cor¡rs€ (gr€abr of prodt¡cr or hydrostalic te3t süBgs). Th€stBss may b€ dskmin€d ushg th€ r€quired ih¡dqless divir€d by ülo tlilsless fpm .a' tl€'l muhtp¡i'd by üls apd¡cabhalory.¿blé stBss:
Produd Stsse = «r¿ - C.{y coroded , ) (Sd)
Hydfo6t lic Test St€es . (r, / nonr¡nal , ) (S,
NO-TE Th6 hiroess€s spocifed ¡n tñe tat h, as we¡ as the wirü so€cif€d h 5.5.2. arg bas€d o.| ú|6 bu tátidr oroviímun¡Drm supporl undsr th€ tuI wirlh of tho a¡nular phb. Unless ü|e bundatEo b Drgo€ñ co.nDad. oertid¡leitv et fñ¡ns¡rr€ ol a concrsb .agwaI, s€üer¡€nt w¡l p@duce additi,nal süss§€s h th€ gnnulai pÉte. -
WELDED TaNKS FoR Ott SToRAGE s-23
where
fd ¡s the design shell thickness, in ¡nches;
fi ¡s the hydrostat¡c test shell thickness, ¡n ¡nches;
D is the nominal tank diameter, in ft (see 5.6.1.1, Note 1);
. H ¡s the des¡gn liquid level. in ft:
is the height from the bottom of the course under consideral¡on to the top of the shell including üe topangle, if any; to the bonom of any overflow that lim¡ts the tank filling height; or to any other level specified bythe Purchaser, restricted by an internalfloating roof, or controlled to allow for seismic wave act¡on,
. G ¡s the des¡gn specif¡c Aravity of the l¡quid to be stored, as specified by the Purchaser;
. CA is the conosion allowance, in inches, as spec¡f¡ed by the Purchaser (see 5.3.2);
S¿ is the allowable súess for the des¡gn condition, in lbf/in.2 (see 5.6.2.1);
S¿ ¡s the allowable stress for the hydrostatic test cond¡tion, ¡n lbfiin.z (see 5.6.2.2).
5.6.4 calculation of Thickness by the var¡able-Des¡gn-Po¡nt Method
NOTE This procedure normally provides a reducl¡on ¡n shell-course th¡cknesses and to[al material weigh, btf more important ¡s
its poremial to permit construction of larger dÉmeter tanks within the maximum plate lhickness limil,alion. For backgroundinformat¡on, see L.P Z¡ck and R.V Mccrath,'Design of Large Diameter Cylindrical Shells "4
. 5.6,4.1 Design by the variable-design-point method gives shell th¡cknesses at des¡gn points that result ¡n thecalculated stresses being relatively close to the aclual c¡rcumferential shell stresses. This method may only be used
when the Purchaser has not spec¡f¡ed that the 1-foot method be used and when the following is true:
ln Sl units:
4 . toooH- 6
where
Z equals (500 D00 5, in mm;
D ¡s the tank d¡ameter, in m;
f is the bottom-course coroded shell th¡ckness, ¡n mm;
¡I is the max¡mum design l¡qu¡d level (see 5.6.3.2), ¡n m.
20 L.P. Zick and R.V Mccrath, "Des¡gn of Large Diameter Cylindrical S,hells,' Pr@eedings-Division of Refining, American
\_. Petroleum lnstitute, New York, 1968, Volume 48, pp. 1114-1140.
API SraNoaRD 650
L .tH --
where
ln USC un¡ts:
I equals (6 Dr)o 5, ¡n inches;
, is the tank d¡arneter, in ft;
¿ is the bottom-course corroded shell th¡ckness, in inches;
-FI is the max¡mum design liquid level (see 5.6.3.2), in ft.
5.6.4.2 The minimum plate thicknesses for both the design cond¡üon ard the hydrostatic test condition shall bedeterm¡ned as outl¡ned. Complete, independent calculat¡ons shall be made for all of the courses for the designcondiüon and for the hydrostatic test cond¡tion. The required shellth¡ckness for mch course shall be the greater of thedes¡gn shell thickness plus any corros¡on allowance or the hydrostaüc test shell th¡ckness, but the total shell th¡cknessshall not be less than the shell thickness requ¡red by 5.6.1.1, 5.6.1.3, and 5.6.1.4. When a greater th¡ckness ¡s usedfor a shell course, the greater thickness may be used for subsequent calculations of the thicknesses of the shellcourses above the course that has the greater thickness, prov¡ded üe greater thickness ¡s shown as üe requireddesign thickness on the Manufacurer's draw¡ng (see W3).
5.6.4.3 fo calculate the bottom-course thicknesses, prel¡m¡nary values tpdand fpr for the design and hydrostatic testconditions shall f¡rst be calculated from the formulas in 5.6.3.2.
5.6.4.4 The bonom-course th¡cknesses Í1¿and ¿1¿for the design and hydrostatic test condit¡ons shall be calculatedusing lhe follow¡ng fomulas:
ln Sl units:
r,,=(roo-YffiP#9tr^
ln USC un¡ts:
,,,= (roo-'fFH(4X\.r^NOTE For the design condition, fld need not be greater than tpúr
ln Sl units:
,,,=(r.oo rP#(Hln USC units:
,,, = (roo-e3f E)("f,NOTE Fof the hydrostatic test condit¡on, ¿1¡need nol be gfeatef lhan tpr.
VVELDEo TANKS FoR OtL S'roRAGE 4-9
Table 4.3a-L¡near Equatjons for Figure 4.1a (Sl) Table 4.38-L¡near Equaüons for Figure4.lb (USC)
APIGroup #
ThicknessRange
Equation
I 6<X<13 Y = 0.7 14X - 16.286
I 13<x<25 Y= l.4t7X-25.411
II 6<X<13 I/= 0.634X- 31.81
II t3 <x< 40 y:1.243X-39.72
IIA l0 sx< t3 Y=2.661X-55.667
II,A l3 <x< l9 Y=2X-47
ILA 19 <x< 40 Y=0.905X-26.19
III 6<X<tl Y=-40
III 13<x<40 Y= 1.222X- 55.89
IIIA 6 <.Y< 40 Y =-40
IV 6<XS40 Y:0.7059X- t8.235
IVA 6 <X< 40 Y - 0.7353X - 23 .412
6<X<40 Y = 0.6t7&Y - 3l .11
VI, VIA 6<X<40 Y= 0.4ll2x - 40.4'11
Y= Des¡gn Metal Temperature ('C)
X= Th¡loess ¡r¡dud¡ng co,rosion (mm)
APIGroup f
Th¡cknessRange Equat¡on
I 025<X<05 Y=40X
I 0.5 <x< 1.0 v:60x- t0
lt 0.25 <X< 0.5 Y=30.4X-25.6
II 0.5 <x< 1.5 Y=60.4X-40.6
IIA 0.375 <X< 0.5 Y = l20X- 65
IIA 0.5 <x< 0.?5 I= 80X- 45
IIA 0.75 <,Í < 1.5 Y=46.661X-20
III 0.25<,Y<0.5 r=- 40
III 0.5 <x< 1.5 Y = 60X -10
IIIA 0.25 <X< 1.5 Y=-40
lv 0.25<X3t.5 Y=34.4X- 1.6
IVA 0.25 <.Y< 1.5 Y=36X-12
0.25 <,r< 1.5 Y=30.4X-25.6
VI, \'IA 0.25 <X< 1.5 Y=20X-41
Y= Oesign Metal Temperature ('F)
,r= ThkJ<ness ¡nduding conos¡on (in.)
4.2.'11.3 For plate in the as-rolled condition, the thid(est plate fom each heat shall be ¡mpad tested. For TMCPmaterial, each platé.as-rolled shall be ¡mpaci tested. lmpa€d testing shall be ¡n accordance with 4.2.9 and shall fulfillthe impasl requirements of 4.2.11.2 at the des¡gn metaltemperature.
' 4.2.11,4 The ManuEcturer shall submit to the Purcñaser test data for plates of the material demonstrat¡ng thatbased on Past produclion from the same mill, thé matedd has prov¡ded the requ¡red toughness at the design metaltemperafure.
4.3 Sheets
Sheets brfixed and floaüng roofs shall conform to ASTM A'lO11M, Grade 33. They shall be made by the open-hearthor basic oxygen process. Copper-bearing steel shall be used if spec¡fied on the pur€ñase order. Sheets may beordered on either a we¡ght or a thickness basis, át the option of the tank Manufac{urer.
4.4 Stuctural Shapes
4.4.1 Slructural steel shall conform to one of the following:
a) ASTM A36M/A36.
! b) ASTM 4131M/A1 31.
c) ASTM A992M/A992.
WEToED TANKS FoR OIL SÍORAGE 4-g
Table 4.3a-Linear Equations for Figure 4.1a (Sl) Table 4 3b-L¡near Equat¡ons for F¡gure 4.1b (USC)
APIGroup #
ThicknessRange
Equat¡on
I 6<X<13 Y= 0.7|1X- 16.286
I 13<X<25 Y= l.4l1X 25.117
IT 6< X< t3 f= 0.634X- 31.81
II 13 <X= 10 Y=1.243X-39.72
trA l0<x<13 Y= 2.667X- 55.«7
IIA 13<x<t9 y:2x 17
ILA t9<x<10 Y= 0.905X-26.19
UI 6<X<13 Y=- 10
m 13<x<13 Y= 1.222X- 55.89
IIIA 6 < X<.t0 Y = -.10
IV 6 < X<40 Y= 0.7059X- 18.235
IVA 6<X<40 I= 0.7353X 23..112
6<<40 Y=0.6116X-31.71
VI. \'IA 6<X<,10 Y=0.4112X- 10.111
f= Desiln Metal remperature ('c)
X= Th¡ckness includ¡ng coroíon (mm)
APIGroup #
ThicknessRange
Equat¡on
I 0.25 < X<0.5 Y= lOX
I 0.5 <x< 1.0 f= 60X- l0
II 0.25 < X< 0.5 Y= 30.4X-25.6
I1 0.5 < x< 0.75 Y= 60.4X - 40.6
I]A 0.375 < X< 0.5 Y= r20X- 65
IIA 0.5 < x< 0.75 f= 80X- 45
ILA 0.75 < X< 0.15 Y= 16.667X- 2O
UI 0.25 < X< 0.5 f= - ,10
Itr 0.5 < x< 1.5 Y=@X-70
IIIA 0.25 < X< t.5 f= - ,10
IV 0.25 < X< 1.5 y:34.4X t.6
IVA 0.25 < X< 1.5 \':36X t2
0.25 < X< t.5 Y=30.4X-25.6
!'t, vtA 0.25 < X< 1.5 Y=20X- 1l
Y= Design Metal Temperature ('F)
X= Thickñess including conosion (in.)
4.2.'.11.3 Fot plate ¡n the as-rolled condition, the thickest plate from each heat shall be ¡mpact tested. Fof TMCPmaterial, each date-as-rolled shall be ¡mpact tested. lmpact testing shall be ¡n accordance with 4.2.9 and shall futf¡ll
the ¡mpact requirements of 4.2.11.2 at the des¡gn metal temperature.
4.2,11,4 The Manufacturer shall subm¡t to the Purchaser test data for plates of the material demonstrating thatbased on past production from the sarne m¡ll, the mater¡al has provided the required toughness at the des¡gn metaltemperature.
4.3 Sheets
Sheets for f¡xed and floating roofs shall conform to ASTM A10l1M, Grade 33. They shall be made by üe open-hearthor bas¡c oxygen process. Copper-bearing steel shall be used if specified on the purchase order. Sheets may beordered on e¡ther a we¡ght or a üickness bas¡s, at the opt¡on of the tank Manufacturer.
4.4 Structural Shapes
4.4.1 Structural steel shall conform to one of üe follow¡ng:
a) ASTM A36M/A36.
b) ASTM 4131¡r/A131.
c) ASTM 4992M/4992.
10"-30'-25"
'-20'?/ 15'
-10.-5'
Compiled lrom U.S. Weather Bureau andMoteorological Div. Dept. ofTransport ofDominion of Canada Records up to '1952.
F¡gure 4.2-lsothermal Lines of Lowest One-Day Mean Temperatures f D f C = CF - 32)l
)) )
!
z
WELDED TANKS FoR O[ SToRAGE
\-' 5.6.4.5 To calculate the second-course th¡cknesses for both the design condition and the hydrostatic test condit¡on,
the value of the follow¡ng ratio shall be calculated for the bottom course:
h1
(rl, )oi
where
h ¡s the height of the bonom shell course, in mm (in.);
r ¡s the nom¡nal tank rad¡us, in mm (in.);
¡l ¡s the calculated conoded th¡ckness of the bottom shell course, in mm (¡n.), used to calculate f2 (design)'
The calculated hydrostaüc thickness of the bottom shell course shall be used to calculate f2 (hydrostatic
teso.
lf the value of the raüo is less than or equal to '1.375:
tz=tt
lf the value of the raüo is greater than or equal to 2.625:
tz : tza
\-' lf the value of the rat¡o ¡s greater than 1.375 but less than 2.625:
tz= rza+Qt t,,P, -#*]
where
rz ¡s the minimum design th¡ckness of the second shell course, in mm (in');
¿2a is the cofroded thickness of üe second shell course' in mm (in.)' as calculated for an uPper shell course as
described in 5.6.4.6, 5.6.4.7, and 5.6.4.8. ln calculaÜng second shell course th¡ckness (f2) for des¡gn case
and hydrostatic test case, applicable values of t2á and fishall be used'
The preceding formula for 12 is based on the same allowable stress be¡ng used for the.design of the bottom and
.""ond "*rSé..
For tanks where the value of the ratio ¡s greater than or equal to 2.625, the allowable stress for üesecond course may be lower than the allowable stress for the bonom course when the rnethods described in 5.6.4.6
through 5.6.4.8 are used.
5.6.4.6 To calculate the upper-course thicknesses for both the design condition and the tydrostat¡c test condition, a
prel¡m¡nary value r, for the upper-course conoded th¡ckness shall be calculated using the formulas ¡n 5.6.3.2, and
inen the ústance ; of the va;iáble design poinr fiom the bottom of the course shall be calculated using the lowest
value obta¡ned from the following:
API STANDARD 650
ln Sl units:
xr = 0.61 (rt¡os*rroro
x2 = 1000 CH
xt = 1.22 (x)o s
where
¡u is the conoded thickness of the upp€r course at lhe ginh jo¡nt, ¡n mm;
C equals UP.s (r- l)l/(l + (l .5);
K quals tL/ tu:
f¿ ¡s the conoded thickness of the lower course at the g¡rth jo¡nL ¡n mm;
. H is the des¡gn l¡quid level (see 5.6.3.2), ¡n m.
ln US Customary un¡ts:
x¡ = 0.61 (rt)0.5 + 3.84 CII
x2 = 12CH
4 = r'22 (¡¡)o s
where
¿u is the conoded thickness of the upper course at the g¡rthjo¡nt in inches;
c equals l¡o,5 (/(- 1)l(l + 14.5);
K quds ql tüi
1¿ ¡s the coroded th¡ckness of the lower course at the ginhjo¡nt, ¡n inches;
. H is the des¡gn liquid level (see 5.6.3.2), inft.
5,6.4.7 The m¡nimum thickness rr for the upper shell courses shall be calculated for both the design condition (r¿)and the hydrostat¡c test condit¡on (¡d using the min¡mum value of x obtained from 5.6.4.6:
ln Sl units:
a s{a-fJc5d
rs{a-fooJ
+CA
WELDED TaN(s FoR OtL SToRAGE
ln USC units:
z.a\a-t)c
,rfu-i)
5.6.4.8 The steps descr¡bed ¡n 5.6.4.6 and 5.6.4.7 shall be repeated using the calculated value of t, as fu until there
is little difference between the calculated values of fxin success¡on (repeat¡ng the steps tw¡ce is normally suff¡cient).
Repeating the step6 provides a more exact locaüon of the design po¡nt for the course under consideration and,
consequenüy, a more accurate shell thickness.
5.6.4.9 fhefe are two examples provided in Annex K. ExamPle #l are step-by-step calculatons illustfat¡ng an
ápltiátion ot tn" rariabte-Oesign-point method to a tank with a diameter of 85 m (280 ft) and a height of 19.2 m (64 ft)
ió ieterr¡n" shell-ptate thicknásses for the first three courses for the hydrostat¡c tesi condiüon only. ExamPle #2
demonstrates the váriable-design-point design method in US Custornary un¡ts for a tank wiü a diameter of 280 ft and
á n ignt of 40 ft with varying ionosion allo:wances and vary¡ng materials for both the design and hydrostat¡c test
conditions.
5.6.5 Calculation of Thickness by Elast¡c Analysis
For tanks where I/¡l is greater than l 000/6 (2 ¡n USC units), the select¡on of shell th¡cknesses shall be based on an
etástic anatysis that sh;ws the calculated circumferent¡al shell sEesses to be below the allowable stresses given in
Table 5.2a ánd Tabte 5.2b. The boundary condiüons for the anal)6is shall assume a fully plastic moment caused by
yielding of the plate b€neath the shell and zero radial growth.
5.7 Shell OPenings
5.7.1 General
5.7.1.1 The following requ¡rernents for shell oPenings are intended to restr¡ct the use of appurtenances to those
providing for attachment to the shell by weld¡ng. See F¡gure 5.6.
5.7.1.2 The shell opening designs described in this standard are required. except for altemative des¡gns allowed in
5.7.1.8.
5.7.1.3 Flush-type cleanout fittings and flush-type shell connections shall conform to the designs specified in 5 7.7
and 5.7.8.
. 5.7.1.4 When a s¡ze intermediate to the sizes listed ¡n Tables 5.3a through 5.12b ¡s specified by the Purchaser, the
construct¡on details and reinforcements shall conform to the ne)d larger open¡ng l¡sted in the tables. fhe size of the
opening or tank connecüon shall not be largef than the maximum size given in the aPpropriate table.
5.7.1.5 Openings near the bottom of a tank shell w¡ll tend to rotate with vert¡cal bend¡ng of üe shell under
hydrostatic'loadiñg. Shell openings in this area that have at¡ached p¡ping or other external loads shall be reinforced
náionty to. rf'" truic condition br-ñ abo for any loads imposed on the shell connect¡ons by the restra¡nt of üe anached
piping ío the shell rotat¡on. The external loadi shall be m¡nimized, or the shell connections shall be relocated outside
in'" rát t¡on ur"u. Annex P provides a method for evaluating openings that conform to Table 5.6a and Table 5.6b.
+CAs",
5-27
5-28 API STANoARo 650
RTR = Regular-Tlpe.Reinforced opening (nozzleor manhole) with diarnond or c¡rcular shape re¡rforcing plate or insen pl¿te üat does nolenend to the bottom (see Figlre 5.7a and Figwe 5.8).
LfR = Low-Type Reinforced.opening (nozzle or rñanhole) us¡ng tombstone type reinforcing plate or insert plale that extends to the bottomlsee F¡gure 5.8, Detarl (a) and Detai¡ (b)1.
S-N = Shell openings.with ne¡ther a re¡rfo.c¡ng plate nor wilh a th¡ckened ¡nsen plate (i.e. ¡ntegrally re¡nforced shell open¡ngs; or open¡ng§not requir¡ng re¡nforc¡ng).
Shellverticál
Bottom plates or anñular plates
VariablesReference M¡n¡mum Dimens¡on Betureen Weld Toes or Weld Centerl¡ne (Notes 1 and 3)
Shell f Cond¡tion
Para-graPh
Numb€r A (2) B (2) c (2) D (3) E (21 F (4) c (4)
¡< 12.5 mm(t < 112in.\
Aswelded
orPWHT
5.7.3.2
5.7.3.3
5.7.3.3
5.7.3.3. 5.7.3.4.5.7.3.4
150 mm (6 ¡n.) 75 mm (3 ¡n.)or 2112t
75 mm (3 ¡n.)or 21121
75 mm (3 ¡n.)for S-N
Table 5.6aand
Table 5.6b
75 mm (3 ¡n.)or 2112t
8t or 1lz r8¡
t > 12.5 ññ(t > 112 in.\
AsWelded
5.7.3.1.a
5.7.3.1.b
5.7.3.3
5.7.3.3
5.7.3.3.5.7.3.4.5.7.3.4
SWor250 mm (10 in.l
8W or25O mm (10
in.)
SWor250 mm(10 ¡n.)
75 mm (3 ¡n.)for S-N Table 5.6a
andTable 5.6b
SWort50 mm (6 in.
8to¡ 1lz r8¡
t > 12.5 mñ(t , 1lz in.\
PWHT 5.7.3.2
5.7.3.3
5.7.3.3
5.7.3.3. 5.7.3.1. 5.7.3.4
150 mm (6 ¡n.) 75 mm (3 ¡n.)or 21lzt
75 mm (3 ¡n.)o¡ 2112t
75 mm (3 ¡n.)for S-N
Table 5.6aand
Table 5.6b
75 mm (3 ¡n.)ot 2112t
Etor 112 rB¡
NOTE I ll two requ¡remeds are $ven, the rin¡mu¡ spac¡ng ¡s the greater va¡ue, elcept for dimen§oñ 'E See Note 4.
NOTE 2 { = shell ñickness. 8rl= 8 üÍ¡es üle largel ¡leld §ze fq re¡rforc¡nq plate o. ¡nsen plate periphery we¡d (ñllet or but-weld) hom ftetoe ol Úle periphery weld to Úle centerliñe of the shell buü-weld. -
NOTE 3 D= spac¡ng d¡9arrce egablished by minimum elevatbn for low-§pe re¡nforced openings froñ Table 5.6a and Table 5.6b, column 9.NOTE 4 Ardlaser option lo allow sllell op€nings to be located ¡n horizor¡lal or venical shell buü-welds. See F¡que 5.9.
r = shell lhbiness, ¡ = radius ol dpen¡n-q. M¡n¡mum spac¡nq fo. dimension F is the less€r ot 8l or r/2 Í "
F¡gure 5.6{ú¡n¡mum Weld Requirements for Open¡ngs in Shells According to 5.7.3
WETDED Tar{Ks FoR Ott SToRAGE 5.29
Table 5.3a-Thickness of Shell Manhole Cover Plate and Bolt¡ng Flange (Sl)
Column I Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column I Column 10
Max.Des¡9nLiquidLevel
mH
Equ¡valentPressurea
kPa
M¡n¡mum Thickness of cover Plateb (rJ, mmMinimum Th¡ckness of Bolting Flange After
Finishingb (rr, mm
50O mmManhole
600 mmManhole
750 mmManhole
900 mmManhole
5OO mmManhole
600 mmManhole
750 mmManhole
90O mmManhole
5.2 51 B 10 11 13 6 6 B 10
6.7 66 10 11 13 '14 6 8 10 11
8.0 18 10 11 14 16 6 8 '11 13
9.9 97 11 13 16 1B B 10 13 14
11 .1 109 13 '14 '16 19 10 11 13 16
13.4 13',I 13 14 18 21 10 11 14 1B
16.1 'I58 14 16 19 22 11 13 16
'18.6 182 '16 18 21 24 13 '14 1B 21
224 1B 19 24 25 13 14 1B 24
a Equivalem pressúe ¡s based on water load¡ng.
b For add¡tion of coÍos¡on allowance, see 5 7.5.2
c Cover Plate and Flange thick¡ess given can be used on Manholes d¡mens¡oned to lD or oD'
NOTE See F¡gure 5.7a. _
Table 5.3b-Th¡ckness of Shell Manhole Cover Plate and Bolting Flange (USC)
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column I Column 10
Max.Des¡gnL¡qu¡dLevel
ftH
EquivalentPressurea
lbflin.2
M¡n¡mum Thickness of Cover Plateb (rJ, in.Minimum Thickness of Bolüng Flange After
Finishingb (rr, in.
20 ¡n.Manhole
24 in.Manhole
30 ¡n.Manhole
36 in.Manhole
20 in.Manhole
24 irl.Manhole
30 ¡n.Manhole
36 in.Manhole
17.',I 7.4 3/a llts I 1tz J/16 3lB
21.9 9.5 3/s the 1lz 9/ro J/16 3/a 7lrc
26.1 11.3 3/s 11rc -/16 slB s/, s
ll..o 112
32.6 14.1 tha 112 J/8 11/ro 5/r e 3/e 112 9/r o
36.5 15.8 1lz 9/r o
5/s 3lc 3/e 71rc 112 s/s
43.9 19 1lz the 1r/r o 13/r o 3/e llt 9/re 11h o
22.9 9/r 6 5/a 3lc 1la llts 1lz 5/8 3lq
6'1.0 26.4 5/B 11/rs l3h o 1sh 6'|
12 9/r s 11/r o 13/ro
15.1 32.5 11h e 3lq 1 5/r e 1 112 9/r o 11h 6 1s/r e
a Equivalent pressure is based on water loading.
b For add¡üon of corosion alloltance, see 5.7.5.2.
c Cover Plate and Flange $¡ckness Oven can be used on Manholes d¡memioned to lD or OD.
NOTE See Figwe 5.7a.
5-30 API STANDARD 650
Thickness of Shell (l) a
Min¡mum Neck Thickness (r) b
For Manhole Diameter500 mm
For Manhole Diameter600 mm
For Manhole Diameter750 mm
Fol Manhole D¡ameter900 mm
5 5 5 5 5
6 6 6 6 6
8 6 6 B I10 6 6 8 'r0
11 6 6 8 10
12.5 6 6 8 10
't4 6 6 B 10
6 6 I 10
18 6 6 I 10
'r9 6 6 B 10
21 I 6 8 10
22 10 B I 10
24 11 1'l 11 1l
25 11 11 11 1'l
27 11 't1 11 11
28 13 13 13 13
30 14 14 14 14
32 16 14 14 14
33 16 16 It) 16
35 11 16 16 16
36 11 17 11 17
3B 20 20 20 20
40 21 21 21 21
41 21 21 21 21
43 22 22 22 22
45 22 22 22 22
lf a shell plate th¡cker than required is used for the product and hydrostatic load¡ng (see 5.6), the excess shell-plate th¡ckness, with¡n avenica¡ d¡slance both above and below the centerline of the hole ¡n the tank shell plate equal to the verticál d¡mens¡on of the hole ¡n the tankshell plate, rñay be cons¡dered as reinforcement, and the h¡ckness lof the manhole reinforcing plate may be decreased accord¡ngly. ln s¡lchcases, the reinforcemert añd the attachmeni vvelding shall conform to the design limits for reinforcement of she open¡ngs specif¡ed in 5.7.2.
The min¡mum neck th¡ckness shall be the requ¡red conoded thickness of the shell plate or the minimum flange üickness of úle bolting flange(see Table 5.3a), whichever is ü¡nner. lf the neck th¡ckñess is greater than the required miñimum, the manhole re¡nforcing plate ú¡cknessñay be deceased accord¡ng¡y. ln srch cases üe re¡nforcemem and the attachment weld¡ng shall conlorñ to the des¡gn l¡mits ot ihereinfqcemeñ of úle shellopen¡ng in 5.7.2.
Table 5.4a-D¡mensions for Shell Manhole Neck Thickness (Sl)D¡mens¡ons in m¡ll¡meters
WELoED TaNKs FoR OtL SToRAGE 5-31
Table 5.4b-D¡mensions for Shell Manhole Neck Thickness (USC)Dimensions ¡n inches
Th¡ckness of Shell (t) a
M¡n¡mum Neck Th¡clness (d b
For Manhole D¡ameter20 ¡n'
For Manhole Diameter21in.
For Manhole D¡ameter30 ¡n.
For Manhole Diameter36 in.
3/ro 31rc J/15 3/r6 3/r e
5/rs J/15 s/r s
3/8 1lt 5he 3/a
llt 1lc 5h6 3/s
llz 1lc s/r o3lg
tho she 3la
JIA J/16 3/e
l1/ro llq J/16 3/B
3lc 546 3lg
13h o 5/r oJ/16 3/B
1le 3is sh6 5ha 3le
1s/r6 1lrc 1lte tha ) l'ts
111rc ) l'ts 7ha 1l.6
11h6 1lrc 7ha 1l'ts tha
11lB 1lz 1lz 1lZ 112
1 3/r esh6 ths the 9/r e
15h 6 5/¿ 9/r o
946 9/r o
13/B s/8 slB sla 5/B
13/a 11h os/g 5/B 5/B
11lrc 11/rs 11h e 11h o11lrc
11123lq 1lt 3lc 3lc
1 9/r e13h o l3/r o
13hs 1 3/r o
ts/s 13/rs 13h o1 3/r o
13l.s
111h6 7lg 1ls 1la lla
1311 1la llB 1lg llB
tt "
s'tr"lt ¡utu tt i"to man required ¡s used for the product and hydro§atic load¡ng (see 5.6), the excess shell'plate th¡ckness, with¡n a vmjcal
distance both above and below the centerl¡ne of tire frole in úre Unf s¡etl plate equal to üe venical d¡mens¡on of Úe hole ¡n the tank shell
plate, may be cons¡dered as reirforcerne¡t and úle ü¡ckness lof the manhole re¡rforcing plaie may be decreased accordiñgly. ln such
tases, thá reinforcement and the attachmeni weld¡ng shall conform to the des¡gn ¡¡mits for re¡nforceñent ol shell open¡ngs specified in 5.7.2
The rÍn¡mum neck th¡ckness shall be üle reqú¡red cofioded dli¡J(ness ol lñe shell plate or fie min¡mum flange ih¡ckness of the bolfng flange
(see Table 5.3b), whichever ¡s thinner. tf üe neck th¡ckness is greater than the required m¡n¡mum, the manhole re¡nforcing dale th¡ckness
may be deceased accord¡ngly. tn $rch cases üe reinforcerneot and üe anachmert welding st|all confom to fle des¡gn limils of the
reirforcernent of úe shell opning ¡n 5.7.2.
API STaNDARD 650
5.7.1.6 Sheared or oxygen-cut surfaces on manhole necks, nozzle necks, reinforcing plates, and shell-plateopenings shall be made un¡form and smooth, w¡th the corners rounded except where the surfaces are fully coveredby attachment welds.
5.7.1.7 Shell open¡ngs may be re¡nforced by the use of an insen plate per Figure 5.7b. The ¡nsert plate may havethe same th¡ckness as an adjacent shell plate or rnay be th¡cker to prov¡de re¡nforcing. A rectangular insert plate shallhave rounded comers (except for edges term¡nat¡ng at the tank bottom or atjoints between shell courses) with arad¡us which is greater than or equal to the larger of 150 mm (6 ¡n.) or 6¡where r ¡s the th¡ckness of the shell courseconta¡n¡ng the insert plate. The insen plate may conta¡n multiple shell openings. The thickness and dimens¡ons of¡nsm plate shall provide the reinforcing required per 5.7.2. The weld spacing shall meet requirements of 5.7.3. Theperiphery of insert plates shall have a 1:4 tapered transition to the th¡ckness of üe adjacent shell plates when theinsert plate thickness exceeds the adjacent shell thickness by more than 3 mm (1/e in,).
5.7.1.8 The shape and d¡mensions of the shell open¡ng reinforcement, illustrated ¡n F¡gure 5.7a, Figure s.7b,andF¡gure 5.8 and dimensioned in the related iables may be altered as long as the re¡nforcement meets the area,welding, and weld spacing requirements outlined in 5.7.2 and 5.7.3. For reinforcing plates greater than 1/2 in. thick,w¡th approval of the Purchaser, reinforcement and welding (excluding weld spacing) of shell open¡ngs that complywith API 620. Sect¡on 5 are acceptable. These statements of permiss¡ble allernatives of shell opening re¡nforcementand welding do not apply to flush-type cleanout f¡tt¡ngs, flush-type shell connections or sim¡lar configurat¡ons.
Table s.sa-D¡mens¡ons for Bolt C¡rcle D¡ameter .Dáand Cover Plate Diameter ,cfor Shell Manholes (St)
Dimensions in m¡llimeters
Column 1 Column 2 Column 3
Manhole D¡ameter O, Bolt Circle D¡ameter Dó Cover Plate Diameter ,c
500 667 730
600 768 832
750 921 984
900 1073 1137
NOTE See Figure 5.7a.
5.7.1.9 The flange facing shall be su¡table for the gasket and bolting employed. Gaskets shall be selected to meetthe service env¡ronrnent so that the required seating load ¡s compatible with the flange raüng and facing, the sfengthof the flange, and ¡ts bolt¡ng (see 4.9).
5.7.2 Re¡nforcement and Welding
5.7.2.1 Open¡ngs in tank shells larger than requ¡red to accomrnodate a NPS 2 flanged or threaded nozzle shall bereinforced. The minimum cross-sect¡onal area of the required reinforcement shall not be less than the product of thevert¡cal diarneter of the hole cut ¡n the shell and the nom¡nal plate ül¡ckness, bú lvhen calculaüons are madé for themax¡mum required thickness cons¡der¡ng all design and hydrostatic test load conditions, the requ¡red th¡ckness maybe used in l¡eu of the nominal plate th¡ckness. The cross-sectional area of the re¡nforcement shall be measuredvertically, co¡ncident with the diameter of the opening.
5.7.2.2 The only shell openings that may ut¡l¡ze welds having less than full penetration through the shell are thosethat do not require re¡nforcement and those that uülize a th¡ckened ¡nsert plate as shown in F¡gure 5.7b and Figure
wE[oED fANKs FoR O[- SToMGE
Table 5.sb-D¡mens¡ons for Bolt Circle D¡ameter Dá and Cover Plate Diameter pd
for Shell Manholes (USC)Dimens¡ons ¡n ¡nches
Column 1 Column 2 Column 3
Manhole Diameter O, Bolt Circle Diameter Dó Cover Plate D¡ameter D.
20 2611a 2831a
24 30lia 3231a
30 361/a 383/a
36 4211a 4431a
NOTE See Figure 5.7a.
5.8. However, any openings listed in Table 3 of the Data Sheet that are marked "yes" under "Full Penetration on
Openings" shall utilize welds that fully penetrate the shell and the reinforcement. if used'
5.7.2.3 Except for flush-§pe openings and connecüons, all eflect¡ve re¡nforcements shall be made within a d¡stance
above and belbw the centé;line of thdshell open¡ng equal to the vert¡cal dimension of the hole ¡n the tank shell plate.
Re¡nforcement may be prov¡ded by any one or any combination of the follow¡ng:
a) The anachment flange of the fltting.
b) The reinforcing plate. Reinforc¡ng plates for manholes, nozzles, and other attachments shall be of the same
nominal comp;sitlon 1i.e. same e§UE P-number and Group Number) as the tank part to which they are attached,
unless approved otherwise by üe Purchaser.
c) The port¡on of the neck of the fitting that may be cons¡dered as reinforcement according to 5.7.2.4.
O ExceSS shell-plate th¡ckness. Re¡nforcement may be provided by any shell-plate thickness in excess of the
th¡ckness req;¡red by the governing load condition within a vert¡cal distance above and below the centerl¡ne of the
hole in the sñell equ;l to ahe vertic;l dimension of the hole ¡n the tank shell plate as long as the extra shell-plate
th¡ckness is the aétual plate thickness used less the required th¡ckness, calculated at üe appl¡cable open¡ng'
consider¡ng all load conditions and the conos¡on allot,ance.
e) fhe mater¡al in the nozzle neck. The strength of the material ¡n the nozzle neck used for reinforcement should
preferably be the same as the strenglh of the tank shell, but lower strength material is permissible as
reinforceítent as long as the neck mateñal has minimum specif¡ed yield and tensile strengths.not less than 70 %
and B0 o/o, respeoivély, of the shell-plate m¡nimum specified y¡eld and tensile strengths. When the mater¡al
strength is gáter tnán or equal to ihe 70 7o and aO o¿ minimum values, the area ¡n the neck available for
re¡nfo-rcemeñt shall be reduced by the rat¡o of the allowable stress in the neck, us¡ng the goveming stress factors,
to the allowable stress ¡n the aitached shell plate. No cred¡t may be taken for the addit¡onal strength of any
reinforc¡ng mater¡al üat has a higher allowable stress than that of tlne shell plate. Neck material that has a yield or
tensile s;ength less than the iO yo or 80 oá min¡mum values may be used, provided that no neck area is
cons¡dered as efiective re¡nforcement.
5.7.2.4 The following portions of the neck of a f¡tting may be cons¡dered pan of the area of reinforcement, except
where proh¡bited by 5.7.2.3, ltem e:
a) The port¡on extending outward from the outs¡de sulace of the tank shell plate to a distance equal to four times the
nec[-wall th¡ckness or, if the neck-wall thickness ¡s reduced within this distance, to the po¡nt oftrans¡üon.
5-" V,*** rtr\A rE A tftr ->API STAñoARD 650
500 mm (20 iñ.) and 600 mm (24 ¡n.) sheli manholes: twenty€¡ght 20 mrnd¡ameter (3/4 in.) bolts in 23 mñ (7/s in.) holes750 mm (30 in.) and 900 mm (36 in.) shell manholes: forty-two 20 mm-d¡ameter (3L iñ.) bol¡s in 23 mm (1a ¡n.) holes(Bolt holes shall straddle the lange vertical céñterl¡ne.)
Gasket (see Note 1):500 mm (20 ¡n.) manhdei 615 nm (253h in.)OD ' 508 mm (20 ¡n.) l0 ' 3 nm (
5-34 API STaNDARo 650
Gasket (s6€ Not6 I ):500 mm (20 ¡n.) marhd€: 645 lfm (2lh in.) O' 5(B rrn (:O ¡ñ.) lD' 3 rfm (r/¡ in.) ü*jgEÉs6m ñm (24 in.) rEñhd€: 7{6Írn (29t in.)O'6t0nn(24¡n.)lD'3Ím(¡fi in.)t\ilaE É7$ rrh (30 ¡n.) ÍErlhd€: 8S Írn (3l/r in-) O' 762 rrfn ($ ¡n.) lD' 3 rfm (ih in.) ti*laE€6q) nñ {36 in. ) mahdá: f051 írí (41¡/. in.) C) ' 914 ¡rn (36 ¡n.) lD' 3 .fm Ci. in.) ü*ls§
(5o6 Figure
6 mm (i/r in.) tolltalehole in reinlorcjng plate,
on horizo.Í,al
Altemaüvo Icircularshape
(se€ Not€ 8)
Arc dimension = W2
(SeeNote 7)
(lncreas6 as nec€ssary forweld clear¿nce)Uniform, smooth sullacg
Rounded I*'ll f
Rounded
\Manhol€
+
Manhole OO
l{IIl, (s€o
Note 4)
S6eNol6 5
Se€ Note 2 H(see Not€ 3)
Deta¡l b
. 7, The m¡n¡mum @nted¡ne elevat¡ons allowed by Table 5.6a, Table5.6b, and F¡gure 5.6 may be used when apprcved by the Pur-qhaser
8. For d¡mens¡ons for Oa DR, D", L, and V w fab¡e 5.6a and Tab¡e5.6b, Columns 2,,1, 5, and 6. For Dimens¡on Dp see Table 5.7a andTable 5.7b. Column 3.
9. At the opüon of the Manufacturer, th6 manhole /D may be set tothe OD dimenslon listed ¡n Table 5,6a and Table 5.6b. Colurnn 2.Re¡nlorcement ar€a and weld spac¡ng must meet 5.7.2 and 5.7.3requirements respeclively.
(soeNob 8)
I
I
See Nole 2
Dota¡l a
NOTES'1. Gasket material shall be specitbd by th€ Purchaser. See 5.7.5.4.2. fhe gasketed trce shaf be madl¡n+fn¡shed to provire a m¡n¡mum
gasket$eariñg winh of ,9 mm e/4 ¡n.).
3. See Table 5.3a and Table 5.3b.4. See Table 5.4a and Table 5,4b.5. The ske of lhe weH shal equal the thbtriess of the ü!¡nner meñber
¡o¡ned.6. The sheg nozzles shown ¡n Figure 5.8 may be substituted for
manholes.
500 mm (20 in.) ánd 600 mm (24 in.) shell manholes: twenty-€ighl20 mmiiamoter(3/. in.) bolts in 23 mm (% in.) holes750 mm (30 ¡n.) and 900 mm (36 in.) sholl m¿nholes: forty-two 20 mm-diamet€r (3/a ¡n.) bolts in 23 mm (ls ¡n.) holes(Bolt hol€s shallstraddle th€ nang6 vortical c6nt6d¡n6.)
'. 230 Í'rn/ F{9
'n. 10 mm¡¡ameter(3,h in.) rcd
125 mm (5')32 mm (1r¿ in.)
l,-1L- l, (see Nole 3)
F¡gure 5.7a-Shell Manhols
.i-=l2D-t--l_-EIEIEl
_l_
Re¡nforcing padshall b6 shap€dto suil tánk
6 mm (r/.
(150 mm [6 in.] mjnimum redius)
Figure&7b
500 mm (20 in.) and 600 mñ (24 in.) manhol6:750 mrn (30 in.) manhole: 900 mm
900 mm (36 in.) mañholo: 1050 mm
(seeNote 4)
(
ftJlanhole or Nozzle
lnsorl-type Re¡ñforcomonl for Manholes and Nozzle3
(
(<\s----r f] n Radioüaph Je«om J (::^"-8i^13^,
Nozzle q-Neck bovol
about 'l
Round(S€e fablesSa.5-6b, 5-7a. and S7b)
I t.s.n\tt*--------------Í -----<)
6fd|/,és5-7a ard 5-7ü A VRound comér if weld <f z
_-,----1To¡t V
I40 mm (11á ¡n.) max¡muml
should be : .$8o degrees --r Ea F : r ;, 8a F-ons I -l*.:á F ifi ,*l-., 8 §*.:É
,n-,) lg;3i § $f,,.*l {;gi4t4gE* g ;+_*»W,JEErÉ"'rl)Lllz-----j fV-s Nl\' -/U -"ff'"H::""1'"il"';ffibPff:""*0"'ot' lU ;;7-----o l\tlorññ(ltiñtrna\irnuñt, l-8 , [4omm(1!/'?in)maxim"l
Lq ,
Nozzle
r Neck bevel should b€ atoui 10 degreos -----;z I rrsááTábrsss{.sálr7*ands7b) t "T,:X::T::aoou\ tvoesreos._z .r..+l--.r I ^
irtrt,; ^///)-"
"'-,'1[,;h /,.//1h(t+t)ri""+r" I ]i e-$\_ V___7mf, I , W__4, ) N\\_rN§I ol Atremarive tl á=
Item d and e)
Notes:1. See Table 5.7a and Tabb 5.7b, Column 3, for the sheü crrlout, wh¡ch shall
nol be less han the outs¡de diameter of the neck plus 1 3 mm (l/2) ¡n.
2. Seo 5.7.3 br minimum spac¡ng of welds at open¡ng coñnecüons.3. The weld s¡ze shall bo eiúler A (from Tabl€ 5.7a and Table 5.7b, baséd on 4
or r, (m¡nimum nec]< th¡ckness from Table 5.4a, Table 5.4b, Table 5.6a, Table5.6b, Table 5.7a and Table 5.7b), whichever ¡s greater.
4. Other pemissible insert deb¡ls are shoúl h F¡gure 5.8 otAPl Slandarú 620.The re¡ñftnement area shal conlbm lo 5.7.2.
5. D¡rnensions and weld sizes that are not showñ are the same as lhoseg¡ven in F¡gurs 5.7a and TaUe 5.4a though Table 5.8b.
. 6. Deta¡ls ol weld¡ng bevels may vary from those shown I agroed lo by thePurchaser.
F¡gure s.7b-Details of Shell Manholes and Nozzles
(
#
t
oE
I
( ( (
É
o
a
o
Nozzle q
.9dPulg¿
N6ck bevel should beabout 10 dogrees
, 1.5 mm (1/16 in.
,^Lr-2,1¿----__rr(S€6Tables 5-7a snd 6-7bl A Z
Round comer ¡f weld <f z
p
thzv
9eiÉEüqEB,99,r¡
da3
_g
B
f
1.5 mm(1/re in.
(Se€ Tábl6s 5-7a and
Round comer if weld <fTorlV
[40 mm (1]i, in ) maximuml
f- our.-(s€s Tabl€s 5-7a áñd 5-7b)
[40 mm (11/, in.) maximum]
mm(1¡oh.) :lr*t a(min)
...,J 45" rs* r"0,"" +2" ""0nmi'¡uin.)
^T7
N ozzle
^ .\3a'E 6',
bE 'o
=q EAlternative ¡ é o.
bev6l E E Et-----r^ e v oV*t;; lh ;ÉV\-- -ll+ É3
1t':1¿¿LN-i -Z nro¡ogr"pt -,/N- (seo 8.1.2.2,Item d and e)
q
mm ('/,6iñ.)
,EE
or0 mm (3/s in.) max¡muml f+t
(min)
92.
lnsoñ-type Reinforcement for Manholes and Nozzles
Notes:1. See Table 5.7a and fable 5.7b, Column 3, for the shell cutout, which shall
not be less than the outside diameter of the neck plus l3 mm (1/2) in
2. See 5.7.3 for minimum spac¡ng of welds at oPen¡ng connect¡ons.
3. The weld íze shall be either A (ftom fable 5.7a and Table 5.7b, based on 1)
or t,(minimum neck lhickness from Table 5.4a, Table 5.4b, Table 5.6a, Table
5,6b, Table 5.7a and Table 5.7b), whichever is greater.
4. Other permiss¡ble ¡nsen deta¡ls are shown in Figure 5 8 of API Standard 620The reinforcement area shall conform to 5.7.2.
5. Dimensions and weld sizes that are not shown are the same as thosegiven in Figure 5.7a and Table 5.4a lhrough Table 5.8b.
a 6. Deta¡ls of welding bevels may vary from those shown if agreed to by thePurchaser.
(See Noto 3)
""''""'""lll]:l2l:4 bevel
Rad¡ographlsee 8.1.2.2,
Item d)
F¡gure 5.7b-Details of Shell Manholes and Nozzles
Tables 5-7a and 5-7b)
¡n.) maximuml
API STANDARD 650
Arc distanceOne 6 mm (1/" iñ.) telltale hole
in reinforcing plate,on hoñzontal centerline
Beñd reinforcing plate toradius of tank shell
Aliemat¡ve shapefor low-type nozzles
See Deta¡lAor B for
--l-'l bottorn edge -'-\<--....----__---......---..'
Diamond Re¡nforcing Plale
Double Flañge
Regular-type Flanged Nozzles, NPS 3 or Larger(Bolt holes shallstraddle flange centerlines)
"o:9-Q -::r- -
Deta¡lA Detail BLow-type Flanged Nozzles, NPS 3 or Larger
(Bolt holes shall straddle flange centerlines)
Special Flange
Note 1)
l/2 [6 mm (1Á in.) minimum]
(See Note 5)
NOTES '1. See 5.1.5.7 for ¡nformafon on the s¡ze ofwelds.
2. See 5.8.9 for informaüon on the coupl¡ngs used ¡n shell nozzles.3. Nozzjes NPS 3 or large. requ¡re re¡rforceme
Deta¡ls of weld¡rE bevels may vary hom thos€ shown if agreed toby lhe Purchaser.Shop weld not attached to bottom plate,
See 5.7.6.2 for ¡nfomat¡on on supdying noz¿es flush or with an
4.
5.
6.¡nternal projection.
Figure 5.8-Shell Nozzles (see Tables 5.6a, 5.6b, 5.7a, 5.7b, 5.8a, and 5.8b)
Single Flange
s-36
(See Figure 5-7b)
600
Chip
WEtDEo TANKS FoR OL SToRAGE
-¡r F-
Type A
-itF- ->lr l-.-; 10 mm (r/s ¡n.)10 mm (3/s in.)
(see Note 2)(see Note 2)
45"
Shell1.5 mm (1i16 ¡n.)
Type B Type C
Figure 5.8-Shell Nozzles (cont¡nueQ
Table 5.6a-Dimens¡ons for Shell Nozzles (Sl)
Type D
Coupl¡ngs and Flanged Fittiñgs, NPS 3,' Through NPS 2 (see Note 3)
NOfES (continued)
7. See Table 5.7a and fable 5. 7b. Column 6.
8.1¿,i,shallbel9mm(3/4in.)orthethicknessofeitherpartFinedbythef¡lletweld'v'/hicheverislessg. iiiá consrucrion deta¡ls apply to unre¡nforced üreaded, norFüreaded, and flanged rbzzles
D¡mensions in millimelers
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 column I Column 9c
NPS(S¡ze ofNozzle)
outsideDiameler of
P¡peOD
NominalThicknessof FlangedNozzle P¡pe
Wallat"
D¡ameter ofHole ¡n
ReinforcingPlateDp
Lengü ofS¡de of width of
Re¡nforc¡ng Re¡nforcingPlateD or PlateDiameter W
L= Do
MinimumDistánce
from Shell-to-Flange
FaceJ
Minimum Distance ÍiomBottom of Tank to Center
of Nozzle
RegularTyped
H¡Low Type
C
Flanged Fin¡ngs
60 1524.O '152 8 3068 3703 400 1641 1534
54 1371 6 1375 2163 3341 400 1488 1342
52 1320.8 1324 2661 3214 400 1431 1331
50 1270.0 1274 2560 3093 400 1387 1280
4B 1219.2 1222 2455 2910 400 1334 1230
46 1168.4 1112 2355 2845 400 1284 1',!80
44 111 7.6 1121 2255 27 25 375 1234 1125
42 1066.8 1070 2155 2605 375 'lt84 1075
40 1016.0 1019 2050 2445 375 1131 1025
3B 965.2 968 1950 2355 350 'r081 975
36 914.4 9'18 1850 2235 350 1031 925
34 863.6 867 1145 2',115 325 979 875
32 812.8 816 '1645 1995 325 929 420
30 762.O 765 '1545 1865 300 879 170
5-37
5-38 API STANDARD 650
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 9c
NPS(S¡ze ofNozzle)
outsideD¡ameter of
P¡peOD
f{ominalThicknessof FlangedNozzle P¡pe
Wallat,
D¡ameter ofHole ¡n
Reinforc¡ngPlateDp
Length ofS¡de of
Re¡nforcingPlateD orD¡ameter
L= D,
Width ofReinforcing
Platew
M¡n¡mumDistance
from Shell-to-Flange
FaceJ
M¡n¡mum D¡stance fromBonom of Tank to Center
of ftlozzle
RegularTyrped
H¡¡
Low Typec
28 111.2 114 1440 1745 300 826 120
26 660.4 664 1340 1625 300 116 670
24 609.6 12.1 613 1255 1525 300 134 630
22 558.8 12.1 562 1155 '1405 215 684 580
20 508.0 12.1 51'l 1055 1285 275 634 525
18 457 .2 't2.1 460 950 11 60 2so 581 475
16 406.4 12.7 410 850 'l035 250 531 425
14 355.6 12.1 359 750 915 250 481 375
12 323.8 't2.7 321 6Bs 840 225 449 345'10 273.O 12.1 216 58s 720 225 399 290
8 219.1 -12.7222 485 590 2N 349 240
6 168.3 10.97 171 400 495 200 306 200
4 114.3 8.56 111 305 385 115 259 150
3 88.9 1.62 92 265 345 175 239 135
Zf 60.3 5.54 63 150 175 h
1112f 48.3 5.OB 'r 50 150 h
1 33.4 6.35 'r 50 150 lr
314f 26.1 5.54 150 150 h
Threaded and Socket-Welded Couplings
3S 108.0 Coupl¡ng 111 .1 285 360 245 145
Zr 16.2 Coupling 79.4 175 tl
1112f 63.5 Coupling 66.7 150
1 44.5 Coupl¡ng 41 .6 150 h
3l1l 35.0 Couplinq 38.1 150 h
a For exfa-soong pipe, see ASTM A53M or A106M for o$er úall th¡cknesses; however, p¡p¡ng mater¡al must confom to 4.5.b The width of the shell plate shall be $ffic¡ent to conta¡n the re¡nforcing plate and to provide clearance hom fte ginhjo¡nt of Úle shell course.c Lo! , type rehforced mzles stEl rpt be located lo$Er ülan úle m¡n¡nrm distance slpvñ ¡n Cdumn 9. The mir¡mn disrance fiom ü¡e bdom
stlofil in Cot¡rm I cor4r¡es with spacirE rules of 5.7.3 and F(¡re 5.6.d Regular type re¡rforced nozzles shall not be localed lo¡¡/er than the min¡mum dislance llry shown ¡n Co¡umn 8 when shell thickness ¡s equal to
or less than 12.5 mm. Greaie. d¡stances may be requ¡red for shells th¡cker than 12.5 mm to meet the m¡n¡mum weld spac¡ng of 5.7.3 andF¡Exe 5.6.
e See fable 5.7a, column 2.
f Fhñged nozzles and co(pl¡ngs in pipe s¡zes NPS 2 or smallef do rpt requ-e re¡fforc¡ng plates. Di wiü be úle d¡ameter of úle hole ¡n üe shell
date, and Wdd ,4 will be as specified ¡n fable 5.7a, Cdumn 6. Re¡nforc¡ng plates rnay be used if the consúlEtion details compay withrdrforced nozde deta¡ls.
s A coupling in an NPS 3 requ¡res re¡nforcernent.
h See 5.7.3 and F¡gure 5.6.
NOTE See F¡¡rre 5.8.
Table 5.6a-Dimensions for Shell Nozzles (Sl) (Continued)Dimensions in millimelers
h
W€rDED fAN(s FoR OrL SToRAGE
Table 5.6b-D¡mens¡ons for Shell Nozzles (USC)Dimensions ¡n inches
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column I Column 9c
NPS(S¡ze ofNozzle)
outs¡deDiameterof P¡pe
OD
NominalTh¡cknessof FlangedNozzle Pipe
wallatn
D¡ameter ofHole ¡n
Reinforc¡n9Plate
Dn
Length ofS¡de of
Re¡nforc¡ngPlateb orDiameterL- Do
Width ofRe¡nforcing
Platew
M¡n¡mumDistance
from Shell-tGFlange
FaceJ
Min¡mum D¡stance fromBottom of Tank to Center
of Nozzle
RegularTyped
H¡¡
Low Typec
Flanged Fitt¡ngs60 60 60r/8 1203l 145311 16 645i8 603is
54 54 54 r/8 1083i1 131112 16 58s/B 543/B
52 52 52118 1043/a 126112 16 565/8 523 tB
50 50 5or/8 1003/1 12131a 16 545/a 503/B
4B 4B 4Br /8 96r/1 111 16 52s18 483i8
46 46 461/B 92311 112 16 505/s 463/8
44 44 44118 883/4 1O7111 15 4Bs/B 44318
42 42 e 42118 8431a , 1o21lz 15 46s/s 423t8
40 40 4or/8 8o3i 1 9731a '15 44518 40318
3B 3B 38r/8 763h 92314 14 42s18 383/8
36 36 361/8 72314 88 14 4os/8 363/B
34 34 34r/8 683/a 83r/a '13 385/8 343/8
32 32 32118 64314 18112 13 365/8 32318
30 30 30r/8 603/4 73112 12 34518 303/8
28 2A 281la 563/4 683/a 12 32518 28318
26 26 26119 5231 64 12 3os/g 26318
24 24 0.50 24118 49112 60 12 24314
22 22 0.50 22118 45112 55r /a 11 27 22314
20 20 0.50 2O1lB 41112 5o112 1',I 20314
18 18 0.50 'l8r /8 37112 t, 45311 10 23 18r11
It) 16 0.50 161/B 33112 403la 10 2'l '163i1
14 14 0.50 14118 29112 36 10 19 1431q
12-t?314 0.50 12tla 21 33 9 1731a 13112
10 103/1 0.50 'lo?/8 23 2811a I 15311 11t lz
B 8s/B 0.50 83 t4 19 2311c 8 1331a 9tl2
6 o.432 63/,4 1531a 19112 I 12118 71lB
4 41lz 0.337 45lg 12 15tla 1 10r /4 6
3 3112 0.300 3s/a 1O1lz 13112 1 9112 51lc
2t 23lB 0.2rB 2112 6 1
5-39
5-40 API STANDARo 650
Dimensions ¡n inches
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 9c
NPS(S¡ze ofNozzle)
outs¡deDiameterof Pipe
OD
NominalTh¡cknessof FlangedNozzle P¡pe
Wallaln
D¡ameter ofHole in
Reinforc¡ngPlateDp
Length ofS¡de of
ReinforcingPlateD orD¡ameterL- Do
w¡dth ofReinforcing
Platew
MinimumDislance
from Shell.to-Flange
FaceJ
M¡nimum Distance froírBottom of Tank to Center
of NozzleRegularTyped
HyLo{v Type
cltl2l 1.90 0.200 2 6 6 n
tr 1 .315 0.250 6 6 n
3l4l 1.05 0.218 6 6 h
Threaded and Socket-Welded Coupl¡ngs3S 4.250 Couplinq 4 3lB 1114 14114 95/8 55/B
Zf 3.000 Coupling 3r/8 7 h
ll lzl 2.500 Coupling 25tB 6 h
1 1.750 Coupling -lt186 h
3l4l 1.375 Coupl¡ng 1112 5 l1
ó For e)dra-süong prpe, see ASTM 453 or A'106 tor oüer wall th¡cknesses; holtever, p¡p¡ng mater¡al ml§t confom to 4.5.
b The width of tfie s¡ell plate shall b€ s{¡ñqc¡ent to conl,a¡n ú|e re¡nforc¡ng phte and b p.ovide dearance trom üe g¡rü jc}int of ñe shell ccl¡.se.
c Lo¡v tloe reirforced mzzbs shall rn be located lo\irer than úle nhimm dis¡afr€ stDwn in Colunn 9. The riniÍum dis¡ance from üle bottoÍlstpüm ií Colurn I corndies wiü spacing n¡¡es of 5.7.3 and F¡$re 5.6.
d Regular type re¡nfo.ced nozzles shall not be located lourer than the m¡n¡mum d¡stance Htv shown in Column 8 when shell th¡ckness is equal toú less rhan 1/2 ¡n. Greatsr distances riay be.equ¡red for shells thicker Ú|an 1/2 in. to meet the Íün¡mum rr'reld spacing ol 5.7.3 and F¡gúe 5.6.
e See Table 5.7b, Column 2-
f Flanged nozzles and couplings ¡n p¡pe §zes NPS 2 or smaller do mt requ¡re reinforcing plates. Diwill be fte d¡ameter of the hole ¡n the shellplate and Weld i4 will be as specmed in Table 5.7b, Colurm 6. Re¡nforcing plates may be used if the corEtudion deta¡ls conply wiflreirforced nozzle details.
I A coupl¡ng in an NPS 3 reqúres re¡nforcernert.
h See 5.7.3 and F¡gúe 5.6-
NOTE See Figre 5.8.
Table 5.6b-Dimens¡ons for Shell Nozzles (USC) (Continued)
Table 5.7a-Dimensions for Shell Nozzles: Pipe, Plate, and Welding Schedules (Sl)
D¡mens¡ons in mill¡meters
Column I Column 2 Column 3 Column 4 Column 5 Column 6
Thickness ofShelland Reinforcing
PlatétandT
Min¡mum P¡peWall Thickness ofFlanged Nozzlesb
Max¡mumDiameter of Hole
¡n Shell Plate(Dp) Equals
Outside Diameterof P¡pe Plus
Sizé of Filletweld a
Size of F¡llet Weld ,4
Nozzles Largerfhan NPS 2
NPs 3L to 2Nozzles
5 12.1 16 5 6 6
6 12.1 16 6 6 6
I 12.7 16 8 6 6
'r0 12.1 It) 10 6 6
11 12.1 16 11 6 6
13 12.7 16 13 6 I14 12.1 20 14 6 I
WELDED TANKs FoR OrL SToRAGE 5-41
Table 5.7a-Dimensions for Shell Nozzles: P¡pe, Plate, and Weld¡ng Schedules (Sl) (Continued)
Dimensions in millimeters
b) fhe portion ly¡ng within the shell-plate th¡ckness.
c) The pon¡on extend¡ng ¡nward from the inside surface of the tank shell plate to the distance specif¡ed in ltem a.
5.7.2.5 The aggregate strength of the weld anaching a ffiing to the shell plate, an ¡nterven¡ng re¡nforcing plate, orbolh shall at least equal the proportion of the forces passing through the ent¡re re¡nforcement that ¡s calculated topass through the f¡tting.
Column 1 Column 2 Column 3 column 4 Column 5 Column 6
Th¡ckness ofShelland Reinforcing
PlatealandT
Minimum Pipewall Thickness ofFlanged Nozzlesb
h
MaximumDiameter of Hole
in Shell Plate(DJ Equals
outsíde Diameterof Pipe Plus
S¡ze of F¡lletweld I
S¡ze of Fillet weld A
Nozzles LargerThan NPS 2
NPs 3L to 2Nozzles
16 12.7 20 It) B I11 12.1 20 18 B I20 12.1 20 20 I B
21 12.7 20 21 10 I22 12.7 20 22 10 I24 12.1 20 24 10 B
25 12.1 20 25 11 I27 14 20 21 '11 I2B 14 20 28 11 B
30 16 20 30 'r3 I32 16 20 32 13 B
33 18 20 33 13 B
35,IB 20 35 14
36 20 20 36 14 8
3B 20 20 38 14 B
40 2-l 20 40 14 8
41 21 20 40 '16 I43 22 20 40 tb B
45 22 20 40 16 8
tf a shellplate thicker than requ¡red is used for the product and hydrostat¡c loading (see 5.6), the excess shell-plate th¡ckness, with¡n á venical
disance both above and below the centeline of the hole iñ üe tank shell plate equal to the ven¡cal d¡mension of üe hole ¡n üe tank shell
plate, may be considered as re¡nforcement, and the úickness l"of the nozzle re¡nforcing plate may be decreased accordingly. ln such cases,
the re¡nforcement and the attachment weld¡ng shallconforñ to the des¡gn lirnits for reiñforcement of shell open¡ngs specified in 5 7.2-
Th¡s column applies to flanged nozzles NPS 26 and larger. See 4 5 for piping materials.
NOTE See Figure 5.8.
5-42 API STANDARD 650
Column 1 Column 2 Column 3 Column ,l Column 5 Column 6
Thickness ofShell M¡n¡mum P¡peand Re¡nforcing Wall fhickness of
Platea Flanged NozzlesblandT l"
MaximumDiameter of Hole
in Shell Plate(Dr¡ Equals
Outside Diameterof P¡pe Plus
S¡ze of FilletWeld B
S¡ze of F¡llet Weld ,4
Nozzles LargerThan NPS 2
NPS 3t to 2Nozzles
3/r o llz s/8 3/.,s 114
1lz s/a 111
s/r o 112 5/8 5/re 1lq
3/8 llz s/s 3lB llc 1lc
1lrc 1lz s/a 11rc 1lc
1lz 112 5/g 112 5/r e
th6 llz 3lq tho 5/r o
s/g 112 3lc s/s 5ho 5/r o
11/ro 112 3lq 11/rs 5h6 5ha
3lc 112 3lc 3lc rl16 5/r e
13/ro llz 3lq 13/ro 3la 5ho
lla 112 3lc llB 3/s
'I5/16 112 3lt 1s/rs 3/s 5ha
1112 3tt 1 tha 5/r e
t1/16 9^o 3lc 11h 6 7lr( 5l.6
11lB 9/r s 3lc 'ttl8 l ltd s/r o
13/16 5/8 3lq 13h 6 112 5he
1114 s/a 3lc 1111 1lz s/r o
15/16 ll/rs 3lc 1sh 6 112 s/r o
13/8 11/ro 3lc 13/g tha 5/r e
17116 3lc 3lc '17116 946 5/r o
11lz 3lc 3lq '1112 th6 5h6
19^ 6 13h 6 3lc '1112 9/r e 5/r o
15/8 13/ro 3lq 1112 5/s 5h6
1ll/r s 718 3lc 11lz s/B J/ 16
'1311 1la 3tt '1112 5/e "/16
lf a shell plate lhicker than required is used for the product and hydrosl,alic load¡ng (see 5.6), the excess shell-plate thickness, with¡n a
ven¡cal d¡starce both above and bebw the centerline of the hole in the tank shell plate equal to the ven¡cal d¡rrEnsion of the hole in üe tankshell date, rnay be coos¡dered as reinforcernent and úle th¡ckness ?of úle noz¿e reinforc¡ng date rnay be decreásed accord¡rEly. ln suchcases, ú¡e re¡nlorcemeflt and the aüachrnent u¡eld¡ng shall confúm to ür€ des¡gn limits for re¡nforcernent of shell open¡rEs specified ¡n 5.7.2.
Th¡s column applies to flanged noz¿es NPS 26 and larger. See ,1.5 fa piping materials.
NOTE See F¡gure 5.8.
Table 5.7b-D¡mensions for Shell Nozzles: P¡pe, Plate, and welding Schedules (USC)
D¡mensions ¡n inches
WELDED TANKS FoR Orr SToRAGE 5-43
Table 5.8a-D¡mensions for Shell Nozzle Flanges (Sl)D¡mens¡ons in millimeters
column1
Column2
Column3
column4
columñ5
Column6
column7
Column8
Column9
column10
Columnfl
column12
NPS(S¡ze ofNozzle)
M¡n¡mumTh¡cknessof Flanoed
o-
Or¡ts¡deD¡ameterof Flarge
A
Diarneterof Ra¡sed
FaceD
D¡arleterof BoltC¡rcle
C
Numberol
Holes
Diameterof
Holes
DiameteroÍ
Bolts
Diameter of BoreMinimuñ D¡ameterof Hub at Poiñt of
weld
Slip-OnType:
Or¡tsideD¡ameterof P¡pe
PlusB
weldirENeckTypeu
81
Slip-OnTypeo
E
weldingNeckTypec
EI
60 79.4 1854 1676 1759 52 4B 45 6.4 a b c
54 16.2 1683 151'l 1594 44 4B 45 6.4 a b
52 13 1626 1461 'r 537 44 48 45 6.4 a b c
50 10 1569 1410 1480 44 48 45 6.4 a b c
48 10 '1510 1360 1426 44 42 40 6.4 ¿ b c
46 68 1460 1295 1365 40 42 40 6.4 a b
44 61 1405 1245 1315 40 42 40 6.4 a b
42 61 1345 1195 1257 36 42 40 6.4 a b
40 65 1290 '1125 1200 36 42 40 6.4 a b c
3B 60 1240 1075 1150 32 42 40 6.4 a b c
36 60 1170 1020 1036 32 42 40 6.4 b c
34 59 1110 960 1029 32 42 40 6.4 ¿ b
32 57 1060 910 978 28 42 40 6.4 a b c
30 54 985 855 914 28 30 6.4 a b c
2A 52 925 795 864 2a 33 30 6.4 a b c
26 50 870 145 806 24 33 30 6.4 a b c
24 48 815 690 750 20 33 30 4.8 a b
22 46 750 640 20 33 30 4.8 a
20 43 1ñ 585 635 20 30 21 4.8 a b
18 40 635 535 511 16 30 21 4,8 b c
16 36 595 470 540 16 21 24 4,8 a b c
14 35 535 415 416 12 27 24 4.8 b
12 32 485 380 432 12 25 22 3.2 a b
10 30 405 325 362 12 25 22 3.2 b c
B 2A 345 210 298 I 23 20 3.2 b
6 25 280 216 24-l 8 23 20 2.4 a b c
4 24 230 157 190 8 19 16 1.6 b c
3 24 190 121 152 4 19 't6 1.6 b c
2 20 150 92 121 4 19 16 1.6 a b
11lz 11 125 13 98 4 16 12 1.6 b
a Br = in§de diarneter of p¡pe.
b E = outs¡de diameter d pipe + 2t,.c Er = outs¡de d¡ameter of pipe.
d Coros¡on allowance, if specmed, need rpt be added to flange and cover th¡cknesses comüng with ASME 816.5 Class 150, ASME 816.1
Class 125, and ASME 816.47 flanges.
NOTE See F¡oure 5.8. The fac¡no dimensbos lq sliD.on and weldino-neck fianoes in NPS 11/, hrouú 20 and NPS 24 are ¡dent¡cal lo thosesoeciñed ¡n ASúE 816.5 tor Chs< 150 steel flanoei. The facino diñensbns ñ flar¡oes in N?S 30:36, 42, 4a, fi, 52,5,t, and 60 are inahreernern wiú ASME 816.1 tor Class 125 cast i¡oñ flanqes. The il¡riensions for larqe flánqes may confom to Series B d ASME 816.47.
5-44 API SfANoARo 650
D¡mensions in inches
Column1
Columñ2
column3
Column4
Column5
Column6
column7
ColumnI ColumnI
Column10
Column1l
column'12
NPS(S¡2e o,Nozzle)
M¡nimumThicknessof Flanged
o
Outs¡deDaameterof Flange
A
D¡ameterof Ra¡s€d
FaceD
of BoltC¡rcle
c
Nrmberof
Holes
Diameterof
Holes
Diarneterof
BoIts
D¡arieter of BoreM¡nimum
Oiameter of Hubat Point of weld
Slip-OnType:
OLnsideD¡añieterof P¡pe
PlusB
weld¡ngNeckrypeu
BI
SlitronType"
E
Weldirlg¡leckTypec
E1
60 3r /8 13 66 69r/a 52 17lA 13lc o.25 a b
54 3 661/1 59112 62314 44 1118 1314 o.25 c c
52 2,le 64 57112 601lZ 44 11lA 1314 o.25 b c
50 2314 6'13/a 55112 5811a 44 -tltB1314 o.25 b c
48 23t1 59112 53112 56 44 'I5/B 11lz o.25 a b c
46 2111'ts 51112 51 533/1 40 1s/s '1112 o.25 a b c
44 2stg 551/1 49 513/4 40 'I5/8 1112 o.25 a b c
42 2slB 53 47 49112 36 'ts/8 11lz 0.25 a b c
40 2112 503i4 4411a 4711a 36 15/8 1112 o.25 a b c
3B 23tB 483t 421 la 451 la 32 '15/g 1112 0.25 a b c
36 23lB 46 4O1 la 423t1 32 1s/B 1112 0.25 ¿ b
34 25h6 43311 37311 4o1lz 32 15/8 '1112 o.2s a b
32 21lt 41311 353Á 38112 28 1s/8 1112 o.25 a b
30 21lB 383/4 333A 36 2A 13lB 1114 o.25 a b
2A 21116 3611? 3lr/a 34 28 13/8 1114 o.25 a b c
26 2 3411a 2911a 3131a 24 13is 11la 0.25 a b
24 11lB 32 27111 29112 20 '13/8 'll la 0.r9 a b c
22 'I r J/16 29112 25114 27114 20 13/8 11la 0.19 ¡ b c
20 'llr/rs 27112 23 25 20 1114 11lB o.19 b c
'18 'I9/r 6 25 21 2231 16 '1114 '11/8 0.19 a b c
16 11116 23112 18112 2111a 16 1r /8 1 o.19 b c
14 1Jl8 21 161/1 I83/4 12 1r /8 '1 0.19 b c
12 11la 19 15 -t7 12 1¡le 0.13 b c
10 13/16 '16 12311 1411a 12 1 llB 0.13 a b
8 11/s '13112 105/8 11311 B 7lB 3lt 0.10 a b
6 1 1'l 81lz 9112 8 1la 3lt 0.10 a b
4 15/r o 9 63/rs 71lZ 8 3lc s/8 0.06 a b
3 15h o 71lz 5 6 4 3lc 5lt 0.06 b c
2 3lc 6 3s/B 43 t1 4 3tc s/8 0.07 b c
11lz rr/ts 5 2t lB 3tlB 4 slB 112 0.07 a b c
4 = ¡rEile diarieter ol ppe.
f= outsire diameter of p¡pe + 2tÉ
a = outs¡de diamete. of p¡pe.
CoÍoli¡on allowance, if specmed, need rEt be added to flange and cover th¡cknesses complying wiú¡ ASME 816.5 Class 150, ASME 816.1
Class 125, and ASME 816.47 flarEes.
NoTE See Fiolre 5.8. The facino dimens¡ons tor s¡io-on and ureldinq.neck ffañqes in NPS 11/2 tkouqh 20 and NPS 24 are ¡dentical to ü¡oseiiiiimc¿ in nsúr sl6.s tor clasí 150 §eel flanoed The tacino d¡ñens¡oos lú flanqes in NPs 30, 36 12' $ Ñ 52,5'1, and 60 are in
á'orément wür eSMg 916.1 Ior Class 125 cas iroñflanqes. TtE dimen$ons for large flánges may corúorm lo Se.ies B of ASME 816.,t7
Table 5.8b-Dimensions for Shell Nozzle Flanges (USC)
WELoED TANKS FOR OIL STORAGE
Table 5.ga-D¡mensions for Flush-Type Cleanout Fmings (Sl)
Table s.gb-Dimensions for Flush-Type Cleanout F¡ttings (USC)Dimensions ¡n ¡nches
Dimensions in m¡llimeters
Column1
Column2
column3
Column4
Column5
Column6
Column7
Column8
cotumn I cohmn9i10
Column11
HeightofOpen¡ng
h
W¡dth ofOpening
b
Arc widlhof Shell
Reinforc¡ngPlate
w
UpperCorierRad¡us
ofopening
1:l
UpperCorner
Radius ofShell
Re¡nforcingPlate
12
Ed9€O¡stanceof Botts
e
Flangewidtha(Except
atBottom)
f3
BottomFlangeWdrh
f,_tffi["'. ",*,+acrng" Bohs
Diameterof
Bolts
203 406 1170 100 360 32 102 89 83 22 20
610 610 1830 300 740 38 102 95 89 36 20
914 1219 27(n 610 1040 38 1t4 121 108 46 24
1219c 12't9 3200 610 '1310 3B 114 121 114 52 24
@s necessary to provk e a '1.5 mm clearance between ttÉ requ¡red neck'io-íang€ weld
and the head of the bolt.
b Refers to spacing at the lot,t er corners of the cleano(lt'fining flange
c only for Group l, ll, lll, or lllA shellmaterials (see 5 7 7 2)'
NOTE See Figure 5.12.
Column1
column2
column3
Column4
Column5
column6
Column7
ColumnI
columnI
Column10
column11
He¡ghtof
Openingh
Width ofOp€ning
b
Arc W¡dthof Shell
Re¡nforcingPlate
w
UpperComerRad¡us
ofOpening
\
UpperCorier
Radius ofShell
Reinforc¡ngPlate4
EdgeDi$anceof Bolts
e
Flangew¡dha(Except
atBonom)
f3
BottomFlangeW¡dth
f2
SpecialBolt
Spac¡ngb
Numberof
Bolts
Diameterof
Bolts
I 16 46 4 14 1114 4 31lz 3114 22 314
24 24 72 12 1112 4 3314 31lz 36 3lq
36 48 106 24 41 1112 4112 4314 41la 46,]
4Bc 48 125 24 51112 11lZ 41lz 5 4112 52 1
@aSneceSsarytoproüdea1/16in.clearancebetweenüerequ¡redneck.to.flangeweldand the head of the bolt.
b Refers to spacing at the lower comers of the cleanoul-ftting ñange.
c Only tor Group l, ll, lll, or lllA shellmaterials (see 5.7.7.2).
NOTE See Figúe 5.12.
5-45
D¡mensions in mill¡meters
Column 1Coh¡nn
2Column
3Coluñn
4column
5Column
6Column
7Colu.nn
8column
ICdumn
10
Max¡múnDes¡onuquÍo
Level, mH
EquivalentPréssure¡
kPá
S¡ze of Open¡ng áx á(Heightx W¡dth)
200 x 400 600 x 600 900 x 1 200 1200 x 1200
Th¡cknessof Bolting
Flange andCoverPlatet
fh¡ckrEssof Bonom
Re¡nlorcinqPlateD
lb
Thicknessof Bolt¡ng
Flange andCoverPlatet
Th¡d«Essof Bottom
ReinforcingPlate.
tb
Th¡cknessof Bolünq
Flange andCoverPlate
fh¡cknessof Bottom
ReinlorciñgPlarÉo
tb
ThickrEssof BoltingFlangeandCoverPlate
n
Th¡cknessof Bottorn
Reinforc¡ngPlate€
tb
6.'r 60 10 13 10 13 16 21 16 22
10.4 101 10 13 13 13 '19 25 21 28
12.5 123 10 '13 .1314 22 2B 22 30
16.1 159 10 13 14 16 24 32 25 33
18.3 179 11 13 16 18 25 33 2A 35'¡ 9.5 191 11 't3 16 '18 27 35 28 36
2'1.9 215 '11 '13 18 19 28 36 30 40a Equivalent pressqe ¡s based oo water loading.b Max¡mum of 25 mm.c Maxirrum of 28 rm.d Max¡mum of4omm.
é Max¡mum of 45 mm.r See 5.7.7.7 when conos¡on allowarrce ¡s specif¡ed.
NOTE See Figl.¡e 5.12.
API STANDARo 650
Table 5.1oa{ú¡n¡mum Th¡ckness of Cover Plate, Bolting Flange, and Bottom Reinforcing Platé for Flush-Type Cleanout F¡ttingsr (SD
Table 5'lobJrilinimum Th¡ckness of cover Plate, Bolting Flange, and Bottom Reinforcing plate for Flush-Type Cleanout F¡n¡ngsr ruSC)
Dimensions in ¡nches
Column 1Column
2Column
3Column
4Column
5Col(mn
6Column
7Co[rnn
8Column
9Column
to
Max¡mumD€sionLiquÍd
Level, mH
Equ¡valentPfessureá
kPa
S¡ze of Opening áx á(Height x W¡dth)
8x16 24x24 36x48 48x48
Thicknessot Bo¡ting
Flanqe arüCover Plate
Th¡cknessof Botlorn
Re¡nforcinopiateb -
lh
Thicknessof BoltingFlangeandCover Plate
Thicknessol Bottodr
ReinforcingPlatec
lb
fh¡cknessof BolüngFlangeandCover Plate
t
Th¡cknesso, Bottorn
ReinforcingPlateo
lb
Thicknessof BoltingFlange andCoverPlate
Th¡cknessof Bottoír
Reinforc¡ngPlatee
tb
?o 4.1 3lB llz 3/8 .t125/8 13h o llB
34 14.1 3/a 112 112 112 3lc ,l l3/r o 1118
4'l 1 7.8 3/a 1lz 112 9/r e lte '1118 llB1 3/r 6
53 23 3/s 112 9/r o 5/B 15/re 1114 1 '15/16
60 26 tha 112 5/8 1'llr 6 1 1sll6 1r/s '13/8
64 27.8 tha 112 5/a 11/r s 11/16 13lB 't118 11116
7? 31.2 7lrc 1lz lrho 3lc 11lB 171't6 '13/16 '1112
a Equivalent tres$re is based oo water loading.b Maximum of 1 in.c Maximum of 1r/s ¡n.
d Maximum of 11/2 ¡n.
€ Maúrum of 13/4 in.I See s.z.u.z r¡,hen corros¡on allowance ¡s specif¡ed.
NOTE See Figúe 5.12.
5-46
wFl DEo TañKs FoR OtL SfoRAGE 5-41
Table 5.1f a-Th¡cknesses and He¡ghts of Shell Reinforcing Plates for Flush-Type Cleanout F¡ttings (Sl)
Table s.11b-Th¡cknesses and He¡ghts of Shell Re¡nforc¡ng Plates for Flush-Type Cleanout Fittings (USC)
D¡mens¡ons ¡n ¡nches
Th¡ckness of Max¡mumLowest Shell Des¡gn Liquid
Course Levelct,t¡ H¡n. ft
He¡ght of Shell Reinforc¡ng Plate forSizebf Open¡ng rx á (He¡ght x W¡dth)
mm
8x16 24 x.24 36x48 48 x 48b
<12Af 14 36 54 12
a Dimensions adand ¿ rnay be varied wihin the l¡rits defined ¡n 5 7.7.
b 4g x 48 flush-type cl€anout fiflings are not perm¡ted for tar*s vríth greater lhan 1r/2 ¡n. lot¡'rest shell course übkness.
c See 5.6.3.2.
5.7.2.6 The aggregate strength of the welds attaching any intervening reinforcing plate to the shell plate shall at
least equat the [io$nion ot tné foces passing through the enüre re¡nforcement that ¡s calculated to pass through the
re¡nforc¡ng plate.
5.7.2.7 fhe attachment weld to the shell along the outer periphery of a reinforcing plate or proprietary connection
that tap welds to the shell shall be considered éffective only for the Parts lying outside the afea bounded by vertical
lines óawn tangent to the shell open¡ng; however, the outer peripheral weld shall be appl¡ed completely aroundlhereinforcement. §ee 5.7.2.8 for allowablé stresses. All of the inner peripheral weld shall be considered effect¡ve. The
strength of the eflective attachment weld shall be considered as the weld's shear resistance at the stress value g¡ven
for filia welds in 5.7.2.8, The size of the outer peripheral weld shall be equal to the üickness of the shell plate or
re¡nfofc¡ng plate. whichever ¡s thinner, bt¡t shall not be greater than 40 mm (11/2 in.). When low-type nozzles are used
with a reiñfórcing plate that extends to the tank bottom (see Figure 5.8), the size of the portion of üe peripheral weld
that anaches the réinforcing plate to the bonom plate shall conform to 5.1.5.7. The inner peripheralweld shall be large
enough to sustain the remainder of the loading.
5.7.2.8 The reinforcement and weld¡ng shall be configured to provide the required strength for the forces covered in
5.7 .?.5 and 5.7 .2.6.
The allowable stresses for the attachfnent elements are:
a) For outer re¡nforcing plate-to-shell and ¡nner re¡nforc¡ng plate-to-nozzle neck f¡llet welds: S¿ x 0.60.
b) For tens¡on across groove welds: 5¿x0.875x0.70
c) For shear in the nozzle neck: S¿x0.80x0.875
Dimensions in m¡llimeters
Th¡ckness of MaximumLowest Shell Design Liquid
Course Levelctt¡ Hmm m
Height of Shell Re¡nforc¡ng Plate forS¡ze of Opening á x á (Height x Width)
mm
20O x 400 600 x 600 900 x 1200 12OO x lzOOb
A <22 350 915 1312 1830
a Dirierls¡ons tdand ¿ rnay be varied with¡n the lirits deñned ¡n 5.7 7.
b 1200 x 12OO flush-type cleanout fitt¡ngs are not perm¡ted lor tanks wiü greater than 38 mm k t¡vest shell cour§e th¡ckness.
c See 5.6.3.2.
API STANoARo 650
where
Sd is the maximum allowable des¡gn stress (the lesser value of the base mater¡als joineo permitted by 5.6.2.1for carbon steel, or by Tables S.za and S.zb for sta¡nless steel.
Stress ¡n f¡llet welds shall be comidered as shear on üe throat of the weld. The throat of the f¡llet shall be assumed tobe 0.707 t¡mes the length of the shorter leg. Tension stress ¡n the groove weld shall be considered to act over theeffective we¡d depth.
5.7.2.9 When two or more open¡ngs are located so that the outer edges (toes) of their normal reinforc¡ng-plate f¡lletwelds are closer than eight t¡mes the s¡ze of the larger of the f¡llet welds, with a m¡nimum of 150 mm (6 ¡n.), they shallbe treated and re¡nforced as follows:
a) All such open¡ngs shall be ¡ncluded in a single reinforcing plate that shall be proportioned for the largest open¡ng inthe group.
b) lf the nornal re¡nforcing plates for the smaller openings in the group, considered separately, fall within the arealimits of the solid portion of the normal plate for the largest open¡ng, the smaller open¡ngs may be included in thenormal plate for the largest opening without an increase ¡n the size of the plate, prov¡ded that if any openingintersects the vert¡cal centerline of another open¡ng, the total width of the final re¡nforcing plate along the verticalcenterline of either opening is not less than üe sum of the widths of the normal plates for the open¡ngs ¡nvolved.
c) lf the normal reinforcing plates for the smaller open¡ngs in the group, cons¡dered separately, do not fall with¡n thearea l¡mits of the solid portion of the nomal plate for the largest opening, the group reinforcing-plate s¡ze andshape shall ¡nclude the outer lim¡ts of the normal reinforc¡ng plates for all the openings in üe group. A change insize Íiom the outer l¡mits of the normal plate for the largest opening to the outer limits of that for the smalleropening farthest from the largest open¡ng shall be accomplished by uniform stra¡ght taper unless the normal platefor any intermed¡ate oPning would extend beyond these l¡mits, in which case uniform straight tapers shalljoin theouter l¡mits of the several normal plates. The provis¡ons of ltem b with respecl to openings on the same oradjacent vertical centerl¡nes also apply in this case.
5.7.2.10 Re¡nforcing plates for shell open¡ngs, or each segment of the plates if üey are not made ¡n one piece, shallbe provided with a 6 mm (1k in.) diarneter telltale hole. Such holes shall be located on the horizontal centerline andshall be open to the atmosphere.
5,7.3 Spac¡ng of Welds around Connections
See Figure 5.6 for spacing requirernents listed in 5.7.3.1, 5.7 .3.2, 5.1.3.3, and 5.7.3.4.
NOTE 1 Additional weld spac¡ng requ¡rements exist in th¡s s¡andard. Other paragraphs and tables dealing with nozzles andmanholes may increase the minimum spac¡ng.
NOTE 2 Whenever stess rel¡ef or thermal stress relief is used ¡n this standard, it shall mean post-weld heat treatment.
5.7.3.1 For non-stress-relieved welds on shell plates over 13 mm (1/z in.) thick, the min¡mum spacing betweenpenetration connecüons and adjacent shell-platejoints shall be govemed by the following.
a) The outer edge or toe of f¡llet around a penetrafon, around the periphery of a th¡ckened insert plate, or around theper¡phery of a reinforcing plate shall be spaced at least the greater of e¡ght t¡mes the weld s¡ze or 250 mm ('10 ¡n.)(d¡mens¡on A or B ¡n F¡gure 5.6) from the centerline of any bun-welded shelljoints.
b) The welds around the periphery of a thickened insert plate, around a re¡nForcing insen plate. or around are¡nforcing plate shall be spaced at least the greater of e¡ght ümes the larger weld size or 150 mm (6 ¡n.)(dimens¡on E ¡n Figure 5.6) from each other.
WEtoED TANKs FoR OrL SToRAGE
5.7.3.2 Where stress-relieving of the periphery weld has been peformed prior to weld¡ng of the adjacent shelljointor where a non-stress-rel¡eved weld ¡s on a shell plate less han or equal to 13 mm (1/z in.) thick, the spac¡ng may be
reduced to 150 mm (6 ¡n.) (d¡mension A in Figure 5.6) from venicaljoints or to the greater of 75 mm (3 in.) or 2112
times the shell thickness (dimension B in Figure 5.6) ftom hor¡zontal joints. The spac¡ng between the welds around
the periphery of a thickened insert plate or aróund a reinforc¡ng plate shall be the greater of 75 mm (3 in.) or 21lz times
the shell thickness (dimens¡on E in F¡gure 5.6).
5.7.3.3 The rules in 5.7.3.1 and 5.7.3.2 shall also apply to the bonom.to-shelljoint (d¡mension C ¡n Figure 5.6)
unless, as an alternat¡ve, the insert plate or re¡nforcing plate extends to the bottom-to-shelljo¡nt and inte6ects it at
approx¡rnately 90 degrees (d¡mens¡on D in Figure 5.6). A minimum disiance of 75 mm (3 an.) shall be maintained
Obiween tne ioe of a Úeld around a nonreinforced penetrat¡on (see 5.7.2.1) and the toe ofthe shell-to-bottom weld.
5.2.3.4 Nozzles and manholes should not be placed in shell weld seams and re¡nforcing pads for nozzles and
manholes should not overlap plate seams (i.e. Figure 5.9, Details a, c, and e should be avoided). lf there is no other
feas¡ble option and the Purihaser accepts the des¡gn, circular shell open¡ngs and reinforcing plates (if used) may be
located in a horizontal or vertical but-welded shelljóint provided that the min¡mum spac¡ng dimensions are met and a
radiograph¡c exam¡nation of the welded shelljoint ¡s conducted. The welded shelljo¡nt shall be fully radiographed for
a ten-gtn equat to three times the diameter of the opening, but the weld seam being removed need not be
radiographed. Radiographic examination shall be in accordance with 8.1.3 through 8.1 .8.
5.7.4 Thermal Stress Relief
S.7.4,,t All flush-type cleanout f¡n¡ngs and flush-type shell connections shall be thermally stress-rel¡eved as an
assembly prior to iñitallation ¡n the tañt shell or aftei installation ¡nto the tank shell ¡f the enüre tank is stress-relieved.
The streás relief shall be canied out within a temperature range of 600 'C to 650 "C (1100 'F to 1200 'F) (see 5.7.4.3
for quenched and tempered materials) for t hour per 25 mm ( l in.) of shell thickness. fhe assembly shall include the
bottom reinforcing plate (or annular plate) and the flange-to-neck weld.
5.7.4.2 When the shell material ¡s Group l, ll, lll, or lllA, all open¡ng connect¡ons NPS 12 or larger in nom¡nal
d¡ameter ¡n a shell plate or thickened insert plate more than 25 mm (1 in.) thick shall be prefabricated into the shell
plate or th¡ckened insert plate, and the prefabricated assembly shall be thermally stress-rel¡eved within a temPerature
iange of 600.c to 650;c (1100'F to 12oo "F) fof t hour per 25 mm (1 in.) of th¡ckness prior to ¡nstal¡afon. The
streis-relieving requ¡remenB need not include the flange-to-neck welds or other nozzle-neck and manhole-neck
attachments, provided the following conditions are fumlled.
a) The welds are outside the reinforcement (see 5.7.2.4).
b) The rhroat dimens¡on of a f¡llet weld in a sl¡p-on flange does not exceed 16 mm (5/8 in.), or the butt joint of a
weld¡ng-neck flange does not exceed 19 mm (3/4 in.). lf the material is prehe^ated to a minimum temperature of
90 "C ('2OO "F) duáng welding, the weld limits of 16 mm (5/e in.) and 19 mm (3/¿ in.) may be increased lo 32 mm
and 40 mm (11/4 in. and lr/2 in.), respect¡vely.
S.?.4.3 When the shell material is Group lV, lVA, V, or Vl. all opening connecüons requ¡ring reinforcement in a shell
plate or ü¡ckened ¡nsert plate more than 13 mm (1iz in.) th¡ck shall be prefabricated into the shell plate or thickened
insen plate, and the prefábricated assembly shall be thermally stress rel¡eved with¡n a temPerature range of 600 "C to
650'C (1100'F to 12OO "F) fort hourper25mm(1 ¡n.) of ü¡ckness prior to installation.
When connections are installed in quenched and tempered material, the maximum thermal stress-relieving
temperature shall not exceed the temper¡ng temperature for the mater¡als in the prefabricated stress-reliev¡ng
assembly. The stress-rel¡eving requiremen§ do not apply to the weld to the bottom annular plate, but they do apply to
flush-typé cleanoút openings when the bottom reinforc¡ng plate is an annular-plate section. The stress-rel¡ev¡ng
requirémenS need not include the flange-to-neck welds or other nozzle-neck and manhole-neck attachrnents,
prov¡ded the condit¡ons of 5.7.4.2 are fulf¡lled.
5,50 API SrANoaRo 650
Minimum spacing shall be I times theshell th¡ckness or 1/, the radius of theopen¡ng, whichever is less
Toe of weld
Deta¡l b
Penetration Without Reinforc¡ng Plata
spacing shall be 8 times theMin¡mum spacing shall be 8 times theshell thickness or1/, the rad¡us ofthe
open¡ng, wh¡chever is less
shellthickness
Q. or
Toe of weld
Toe of weld
Re¡nforcing
Deta¡l d
Penetrat¡on W¡th Re¡nforc¡ng Plate
o).9!
o
Lrl
I
.l>ott.lcDl0lE*:l9t(,, ql
ñ st
I
g
.9E(!
o
ot¡,1
Detail e
Figure 5.9-Minimum Spacing of Welds and Extent of Related Radiographic Examinat¡on
q of butt-weldedshelljo¡nt
q of butt-weldedshelljo¡nt
WELoEo TaNKs FoR OrL SToRAGE
5.7.4.4 Exam¡naüon after stress relief shall be in accordance w¡th 7.2.3.6 or 7.2.3.7.
5.7.4.5 When it ¡s ¡mpractical to stfess relieve at a m¡nimum temperature of 600 "C (110O'F), it ¡s permiss¡ble,
subject to the Purchaser's agreement, to carry or.¡t the stress-rel¡eving operation at lower tempeJatures for longer
per¡ods of t¡me in accordance with the tabulation below. The lower temperature/longer üme PWHT may not prov¡de
material toughness and residual súesses equivalent to that using the higher temperaure/shorter time PWHT;
therefore. a ieview by a knowledgeable metallurg¡st and poss¡ble verificat¡on by m¡ll test¡ng of heat-tfeated coupons
and/or testing of weided plates ihall be cons¡dred. See Line 23 of the Data Sheet for any Purchaser-specified
requ¡rements applicable to this heat-treatment opt¡on.
M¡n¡mum Stress-Rel¡ev¡ng TemPeratureHolding Time
(hours per 25 mm [1 ¡n.]of thickness)fF)("c) See Note
600
570
540
510
48O (m¡n.)
1100
'r 050
10m
950
9OO (min.)
1
2
4
10
20
1
1
1
1,2
1,2
NOTE 1 For ¡rtemediate temperatures. he tirne of heat¡ng shall be determ¡ned by s¡ra¡ght line interpolation.
NOÍE 2 Stress rel¡eving at these temperatures ¡s not perm¡tted for A537 class 2 material
5.7.4.6 When used in stress-relieved assemblies, the material of quenched and tempered steels A537, Cl2, and
A678, Grade B, and of TMCP steel A841 shall be represented by test spec¡mens that have been subjected to the
same heat treatment as that used for the stress relieved assembly.
5.7.5 Shell Manholes
5.7.s.1 Shell manholes shall conform to F¡gure 5.7a and Figure 5.7b and Table 5.3a through Table 5.5b (or Table
5.6a through Table 5.8b), but other shapes ie permitted by 5.7.1.8. Manhole reinforcing plates.or each segment of
the plates if rhey are not made in one p¡i:ce shati be provided with a 6 mm (1/¿ in.) diameter telltale hole (for detecüon
otidaXage ttrroúgn the interior welds). Each hole shall be located on the horizontal centerline and shall be open to the
atmosphere.
5.7.5.2 Manholes shall be of bu¡h-up welded construct¡on. The d¡rnensions are listed in Tables 5.3a throrgh 5.5b. Th€
dirnensions are based on the minimúm neck thicknesses lisied ¡n Tables 5.4a and 5.4b. When conos¡on allowance is
specified to be applied to shell manholes, conosion allowance ¡s to be added to the minimum neck. cover plate. and
bolting flange thicknesses of Table 5.3a, Table 5.3b, Table 5.4a, and Table 5.4b.
5.7.5.3 The maximum diameter D, of a shell crrtout shall be as l¡sted in Column 3 of Table 5.7a and Table 5.7b.
D¡mensions for required reinforcing blates are listed in Table 5.6a and Table 5.6b.
5.7.5.4 The gasket materials shall meet serv¡ce requ¡rements based on the product stored, max¡mum design
temperature, a-nd f¡re res¡stance. Gasket dimens¡ons, when used in conjunction with thin-plate flanges described in
Figúre 5.7a, have proven efiecüve when used with soft gaskeE, such as non-asbestos fiber with suitable b¡nder.
W"hen using hard gáskets, such as solid metal, corrugated metal, metal-jacketed, and spiral-wound metal, the gasket
dimensioní manhr-ole flange, and manhole cover sháll be designed per API Standard 620, Section 3.20 and Sect¡on
3.21. See 4.9 for additional requ¡rements.
5.7.5.5 ln lieu of us¡ng Figure 5.7a or des¡gn per API 620, forged flanges and forged blind flanges rnay be tum¡shed
per 4.6.
5-51
API STANoARo 650
5.7.6 Shell Nozzles and Flanges
5.7.6.1.a Unless otherw¡se specified, shell nozzle flanges, excluding manholes, in sizes NPS 11/2 throughNPS 20 and NPS 24 shall meet the requ¡rements of ASME 816.5. For sizes larger than NPS 24 but not greaterthan NPS 60, flanges shall meet the requirements of ASME 816.47, Ser¡es A or Series B. Series A and SeriesB flanges are not compatible ¡n all sizes and must be carefully selected to match the mating flange. lfdiameters, mater¡als of consfuction, and flange styles of ASME 816.47 are unavailable, fabricated flanges withdrill¡ng template (bolt circle d¡ameter, number of holes, and hole d¡ameter) match¡ng Ser¡es A or Series B shallbe used. These fabr¡cated flanges shall be designed in accordance with the ASME Bo¡ler and Pressure VesselCode Sect¡on Vlll, Divis¡on 1, Sect¡on UG-34 and Annex 2. The allowable stresses for des¡gn shall be a matterof agreement between the Purchaser and the Manufacturer. Bolt holes shall straddle the venical centerl¡ne ofthe flange.
5.7.6.1.b Shell nozzles (and flanges, if spec¡f¡ed by üe Purchaser as an alternate to a. above) shall conform toFigure 5.7b, Figure 5.8, and F¡gure 5.10 and Tables 5.6a through 5.8b, bu other shapes are permitted by 5.7.1.8. Analtemative connection design ¡s permissible for the nozzle end that is not welded to the shell, if it provides equivalentstrengü, toughness, leak t¡ghtness, and util¡ty and ifthe Purchaser agrees to its use ¡n writ¡ng.
Ring Typ€ Welding Flangé Sl¡p.on Weld¡ng Flarge
1.5 mm
Wéld¡ng-neck FIange Lap Jo¡nt F¡ange
NOTE The tn designated for weld th¡ckness ¡s the nomiñal pipe wall th¡ckness (see Táles 5-6a, s$b, 5-7a, and 5-7b).
Figure 5.10-Shell Nozzle Flanges (see Table 5.8a and Table 5.8b)
5.7.6.2 Unless shell nozzles are spec¡f¡ed to be flush on the ins¡de of the tank shell by the Purchaser, shell nozzleswithout ¡ntemal piping in a tank without a floaüng roof may be supplied flush or with an ¡nternal prqjecüon at üe optionof the Manufacturer. ln floating roof tanks, shell nozzles withoit intemal piping within operat¡ng range ofüe floatingroof shall be supplied flush on the inside of the tank shell unless agreed otherwise between the Manutacturer and thePurchaser.
cA
cA
C
A
ioT
1.5 mm¡, + 6 mm (1/¡ in.) + 6 mm (tl in.)
____+ |_>l
WELoED TANKS FOR OIL STORAGE
where
Acs
5.7.6.3 The deta¡ls and dimensions specified in th¡s standard are for nozzles installed Úth üe¡r axes perpend¡cular
to the shell plate. A nozzle may be installed at an angle other than 90 degrees to the shell plate in a hor¡zontal plane,
provided thó width of the reinfórcing plate (lyor Do in Figure 5.8 and Table 5.6a and Table 5.6b) is ¡ncreased by the
ámour¡t that the horizontal chord of the opening cut in the shell plate (Dp in Figure 5.8 and Table 5.7a and Table 5.7b)
¡ncreases as the open¡ng is changed from c¡rcular to elliptical for the angular installation. ln add¡tion, nozzles not
larger than NPS 3-for the insert¡on of thermometer wells, for samPl¡ng connect¡ons, or for other purposes not
invótuing the anachment of extended p¡p¡ng-may be ¡nstalled at an angle of 15 degrees or less off perpend¡cular ¡n a
vertical plane without mod¡f¡cation of the nozzle re¡nforc¡ng plate.
5.2.6.4 The m¡n¡mum nom¡nal thickness of nozzle necks to be used shall be equal to the required thickness as
identified by the term l, in Table 5.6a and Table 5.6b, Column 3.
5.7.7 Flush-TypeCleanout Fittings
5.7.7.1 Flush-type cleanoü l¡nings shall confom to the requirernents of 5.7.7.2 throlgh 5.7.7.12 and to the deta¡ls and
dimensions shown in Figure 5.12 ánd F¡gure 5.13 and Tables 5.9a through 5.11b. When a size intermediate tothe s¡zes
given ¡n Tables 5.9a thiough S.ttb is ipecified by the Purchaser, the consmldion dela¡ls and reinforcernents shall
;onform to the next larger ofening listed ¡n the tables. The size of the opening or tank connection shall not be larger than
the maximum size given ¡n the approFiate table.
5.2.7.2 The opening shall be rectangular, but the upper corners of the opening shall have a radius. (r]) as shown in
Table S.ga and'Tablt5.9b. When the:hell material is Group l, ll, lll, or lllA, the widlh or height of the clear opening
shall not exceed l2OOmm (48¡n.); when the shell mater¡al is Group lV, lVA, V orVl, the he¡ght shall notexceed 900
mm (36 ¡n.).
5.7.7.3 The reinforced opening shall be completely preassembled into a shell plate, and the completed unit,
including the shell plate at the cÉanout fining, shall bé thermally stress-rel¡eved as described ¡n 5.7.4 (regardless of
the th¡ckness or strength of the material).
5.7.7.4 The required cross-sectional area of üe re¡nforcement over the top of the open¡ng shall be calculated for
Des¡gn Condition as well as Hydrostatic Test Condition as follows:
K. ht4,,>i
K1
h
is the requ¡red cross-sectional area of the reinforcement over the top of the opening, ¡n mm2 (in 2);
is the area coemcient from Figure 5.11;
¡s the vertical height of clear opening, ¡n mm (¡n.);
is the calculated thickness ofthe lowest shell colrse, ¡n mm (¡n.), required by the formulas of 5.6.3, 5.6.4, or
A.4.1 (with joint efiic¡ency E = 1.0), ¡nclud¡ng conosion allowance, where appl¡cable.
5.7.7.5 The nominal thickness of the shell plate in the flush-type cleanout f¡tting assembly shall be at least as th¡ck
as the adjacent shell plate nominal thickness in the lowest shell course. The nominal thickness of the shell re¡nforcing
plate and the neck pláte shall be, as a m¡nimum, the thickness of the shell plate in the cleanout-opening assembly.
The reinforcement in the plane of the shell shall be provided within a he¡ght ¿ above the bottom of the open¡ng ¿ shall
not exceed 1 .5i except that, ¡n the case of srnall open¡ngs, ¿ - /, shall not be less than 150 mm (6 ¡n.). Where this
exception results ¡n an ¿ that is greater than 1 .5r, only the portion of the reinforcement that is within the height of 1.5á
API STANDARD 650
shall be cons¡dered effect¡ve. The reinforcernent required may be provided by any one or any combination of thefollowing.
a) The shell reinforc¡ng plate.
b) Any th¡ckness of the shell plate ¡n the flush-type cleanout f¡tting assembly that ¡s greater than the requ¡redthickness of lowest shell course, as determined by 5.6.3, 5.6.4, or A.4.1 (withjo¡nt efi¡ciency E = 1 .0).
c) The pon¡on of the neck plate having a length equal to the nom¡nal thickness of the reinforcing plate.
Re¡nforc¡ng area provided shall be adequate for Des¡gn Condit¡ons as well as Hydrostatic test Conditions.
Vertical axis in Sl units:
f (H+ 8.8)D + 71.51 [ i23t 'l05
L 1¿oeh I L4.ro (H- o 3il
Vert¡cal ax¡s ¡n US Customary units:
f lu + zs')o +tto1[ rz,esor 10.L 385,, I lz6D (H - 1))
r'o " o *.*'o"n, 13 1'4
Figure 5.11-Area Coefficiem for Detemining Minimum Re¡nforcement of Flush-type Cleanout FiE¡ngs
5.7.7.6 The m¡n¡mum widh of the tank-bottom re¡nforc¡ng plate at the centerline of the opening shall be 250 mm (t0¡n.) plus the comb¡ned nom¡nal th¡ckness of the shell plate ¡n the cleanout-opening assembly and the shell re¡nforcingplate.
The nominal th¡ckness of the bonom re¡nforcing plate shall be not less lhan that determ¡ned by the following equaüon:
ln Sl un¡[s:
t,= ffi,ftJ-nc*cewhere
fD ¡s the m¡nimum thickness of the bottom re¡nforcing date, ¡n mm;
á ¡s the vert¡cal he{lht of clear opening, in mm;
ó ¡s the horizontal widh of clear open¡ng, ¡n mm;
1.25
WELoED TaNKS FoR Ot! SIoRAGE 5-55
Shell p¡ateof lowestshell
Nearest horizontal weld
See Détáil b
Shell plate at cléanout frttiñg = ld
(See Note 5)
Reinforcing plate = ld
tts-w ts,.¡ ---¿ ,,- l0 mm (3/s in')thick
5mm(3/ro in.) Cover plate
Deta¡la
375 mml5 in.) m¡n
I
-I see
One telltale 6 mm(1/. ¡n.)hole inre¡nforcingplate at aboutmid-height
1)Note_(:T
Flange bollhole
Notch as requ¡red to provide flush joint under shell ring (see Section D-D)
imm, in.)§
Section A-A
Grind radius on cornerwhen weld is less lhan td
-dfd r-.-r l--;-5üiii,i;'- -7U¿,L Fur-nret L-+H-/+- -
"+.rMffie ;/ry\,ii1l*.,*,,,
D
Sect¡on B.B
75 mm (3 in.) rad¡us
Section D-D
90 degrees t 30 degrees
--__t---l
125 mm (5 in )mm (1l/a in.) m¡n
6(See
Note 1)
fs ím f/.
to-v\tOl.* - \
andgnnd/ t"
/(See Note 5)
Neck bevel shall beapprox¡mately 1 0 degrees
F¡gure 5.12-Flush-Type Cleanout F¡tt¡ngs (see Tables 5.9a, 5'9b, 5.10a, 5.10b, 5.1'la, and 5.11b)
B
-6mm(rá
(See Note
a125 mm
I
I
,- + Equalspaces J A<rw2 arc d¡mensioñs -....................._l
t¿+ fd+ 250 mm (10 i(see Note
Section Cc
5-56 API STANDARD 650
Botlom reinforcing plále<- Cover plate
(SeeOetail a)
l,Y + 900 mm (36 ¡ñ.) min(ses Tables $9a
and +9b for Wvalues)Weld afterfü¡ng ¡s¡nstalled(see Note 1)mm (1/¡ ¡n.) m¡n
lnside of shell
600 mm (24 in.) m¡n
(SeeDetai¡
<- Cover plale
Cover plateBottom
100-300 mm (4-12 in.)
lnsire of shell
rm (24 ¡n.) m¡n
I300 mm
¡12 ¡n I min(See Deta¡la jc and d) ..---l-
(SeeDetail
R¡ngwall notch
R¡ngwall
lns¡de of shell atcenterline of open¡ng
600 mm (24 in.) min
snettptate )
Method A-Tank Rest¡ng On Earth Grade (see Note 2)
lry+ 900 mm (36 in.) min(see Tables Sga
and 5-9b for Wvalues)
M€thod O-Tañk Résting On Earth Grade lñsidoConcretG R¡ng¡Yall (see Note 3)
Figure 5.13-Flush-type Cleanout Fming Supports (see 5.7.7)
t/+ 300 mm ('12 in.) min, except as l¡mitedby foundat¡on cuNature in Deta¡ld
(see Tables tga and tgb ior Wvalues)
300 mm (12 ¡n.) m¡n
Detail d
Notch to su¡t botlom ré¡nforcing plátelnside of shell atcenterliñe of open¡ng
300 mm (12 in.) min
lnside of she¡lat centeri¡neofopening
300 mm(12 ¡n.)m¡n
lnside of shell atcenterline of opeñing
600 mm (24 in.) m¡n
+300 mm
C-","f" o, r""*ry /
Method B-lañk Resting On Earth Grade (see Note 3)
Nolch to suit bottom reinforcing plate
lns¡de ol shell Detailc
plate
Altemalivenolcfi detail
100-300 mm (4-12 ¡n.)ln§dg of shellRetain¡ng wallConstruct¡oÍ jo¡nt, to permiltañk and retainiñO wáll toseüle indepeñdenüyñom riñgwall
Method C-Tank Rest¡ng On Concrete Ringwall (soe Note 3)
lnside of shellat centerlineof opeñing
Detail e
WELoED TaNKs FoR OtL SToRAGE 5,57
i/ is the max¡mum design liquid level (see 5.6.3.2), in m;
G ¡s the specific gravity, not less than 1.0.
ln USC units:
,,= ffi*fttr"*rowhere
fD is the minimum thickness of the bottom reinforcing plate, ¡n inches;
á is the vertical height of clear open¡ng, in ¡nches;
ó is the horizontal w¡dth of clear opening, in ¡nches;
¡l is the max¡mum des¡gn liqu¡d level (see 5.6.3.2), ¡n feet;
G is the specific gravity, not less than 1.0.
5.7.7.2 The dimens¡ons of üe cover plate, bohing flarEe, bolting, and boüom-reinforc¡ng plate shall conform to Table
5.9a, Table 5.9b, Table 5.10a and Tabie 5.10b. When conosion allowance ¡s specified, it ¡s to be added to the cover
plate, bolting flange thicknesses, and bottom-reinforcing Plate.
5.7.2.g All rnaterials ¡n the flush-type cleanout fitting assembly shall confom to the requirements in Section 4. The
shell plate containing the cleanout assembly, the shell reinforc¡ng plate, the neck plate, and the bottom reinforcing
pbte lnatt meet thiimpact test requ¡remeñts of 4.2.9 and F¡gure 4.1 for the respecüve thickness involved at üebesign metal temperatuie for üe tank. The notch toughness of the bolting flange and the coverllate shall be based
on tñe governing th¡ckness as def¡ned ¡n 4.5.5.3 using Table 4.3a, Table 4.3b, and F¡gure 4.1. Addit¡onally, the yield
strengtñ and thjtensile súength of the shell plate at the flush-type cleanout ffting, the shell reinforcing plate, and the
necf'ptate shall be equal to, á greater than, tne yietO strength and the tensile strength of the adjacent lowest shell
course plate material.
5.2.7.9 The d¡mensions and details of the cleanout-opening assemblies covered by th¡s section are based on
intemal hydrostatic loading w¡th no external-pip¡ng load¡ng.
5.2.7.10 When a flush-type cleanout frn¡ng ¡s installed on a tank that ¡s resting on an earth grade without concrete or
masonry walls under the -tank
shell, provision shall be made to suppon the f¡ning and reta¡n the grade by e¡ther of the
following methods:
a) lnstall a vertical steel bulkhead plate under the tank, along the contour of the tank shell, symmetrical with the
opening, as shown ¡n Figure 5.13, Method A.
b) lnstall a concrete or m¿lsonry retaining wall under the tank with the wall's outer face conforming to the contour of
the tank shell as shown in Figure 5.13, Method B.
5.7.7.11 When a flush-type cleanoü füing ¡s ¡nstalled on a tank that ¡s resting on a r¡ngwall, a notch with the
d¡mens¡ons shown in Figure 5.13, Method C, shall be prov¡ded to accommodate the cleanoÚ ffting.
5.7.7.12 When a flush-type cleanout f¡ning ¡s ¡nstalled on a tank that is resüng on an earth grade ¡nside a foundation
retaining wall, a notch sháll be provided in the retaining wall to accommodate the fitting, and a supplementary ins¡de
reta¡niné wall shall be provided to support the fitt¡ng and retain üe grade. The dimens¡ons shall be as shown in Figure
5.13, Method D.
API STANDARo 650
5.7.8 Flush-Type Shell Connect¡ons
. 5.7.8.1 Tanks may have flush-type connections at the lower edge of the shell. Each connection may be made flushw¡th the flat bottom under the following cond¡t¡ons (see Figure 5.14).
a) The shell upl¡ft from the ¡nternal design and test pressures (see Annex F) and w¡nd and earthquake loads (seeAnnex E) shall be counteracted so that no up¡¡ft w¡ll occur at the cylindr¡cal-sheluflat-bottomjunction.
b) The vertical or meridional membrane stress ¡n the cylindrical shell at the top of the opening for the flush-typeconnect¡on shall not exceed one-tenth of the circumferent¡al design stress in the lowest shell course conta¡ning theopen¡ng.
c) The maximum width, ¿ of the flush-type connection opening ¡n the cyl¡ndrical shell shall not exceed 90O mm (36in.).
d) The max¡mum height, 1,, of the open¡ng in the cylindr¡cal shellshall not exceed 300 mm (12 in.).
e) The th¡ckness, fa of the bottom-úansition plate in üe assembly shall be 13 mm (Uz in.) min¡mum or, whenspecmed, the same as the thickness of the tank annular plate.
5.7.8.2 The details of the connect¡on shall conform to those shown in Figure 5.14, and the dimens¡ons of theconnect¡on shallconform to Table 5.12a and Table 5.12b and to the requirements of 5.7.8.3 through 5.7.8.11.
Table 5.12a-Dimensions for Flush-Type Shell Connect¡ons (Sl)D¡mensions in m¡llimeters
Class l50Nom¡nal Heightof Flange S¡ze
Height ofOpen¡n9
h
widrh ofOpening
b
Arc w¡dth of shellRe¡nforcing Plate
w
Upper ComerRad¡us
of Opening\
Lower ComerRadius of Shell
Re¡nforcing Platef2
B 200 200 9s0 OD of 8 NPSa 350't2 300 300 1300 OD of 12 NPSa 450
16 300 500 1600 '150 450
18 300 550 'r650 150 450
20 300 625 -t725 150 450
24 300 900 2225 150 450a For circt¡ta openings, this value wii be 1/2 ol the ID based on üe noz¿e neck specif¡ed.
NOTE See Figure 5.14.
5.7.8.3 The reinforced connect¡on shall be completely preassembled into a shell plate. The completed assembly,including the shell plate containing the connect¡on, shall be thermally stress-relieved at a temperature of 600 'C to650'C (1100'F to 1200 "F) for t hour per 25 mm (1 in.) of shell-plate thickness, ¡d (see 5.7.4.1 and 5.7.4.2).
5.7.8.4 The reinforcement for a flush{ype shell connect¡on shall meet the follow¡ng requirements:
a) The cross-sect¡onal area of üe reinforcernent over the top of the connect¡on shall not be less than 1(r¿l2 (see5.7.7.41.
b) Ttle nom¡nal th¡ckness of the shell plate, rd for tlle flush-connection assembly shall be at least as thick as theaqjacent shell plate nom¡nal thickness, ¿ in the lowest shell course.
c) The nom¡nal thickness of the shell reinforcing plate shall be, as a min¡mum, the nom¡nal üickness of the shellplate ¡n the flush-connecl¡on assembly.
WELDED fANxs FoR OrL SToR GE
Table 5.12b--D¡mens¡ons for Flush-TyPe Shell Connections (USC)Dimensions in inches
Class 150Nominal Heightof Flange Size
Height ofOpening
h
W¡dth ofOpen¡ng
b
Arc Width of shellRe¡nforcing Plate
w
Upper ComerRadius
of OpeningÍ1
Lor .er ComerRadius of shell
Reinforcing Platef2
I 8s/8 85/B 38 4a 14
12 123t4 12311 52 4a '18
'16 12 20 64 6 18
18 12 22 66 6 1B
20 12 25 69 6 18
24 12 36 89 6 1B
@D based on the nozzle neck speciñed.
NOTE See Figure 5.14.
O The reinforcement in rhe plane of üe shell shall be provided wiü¡n a height ¿ above the bottom of the opening. ¿
shall not exceed 1.51¡ except that, ¡n the case of small open¡ngs, ¿ - á shall not be less than 150 mm (6 ¡n.). Where
th¡s exception results in an ¿ that ¡s greater than 1 .5r, only the portion of the reinforcement that is within the height
of 1 .5, shall be considered effective.
e) The required re¡nforcement may be prov¡ded by any one or any comb¡nation of the follow¡ng:
1) the shell re¡nforc¡ng plate;
2) any th¡ckness of the shell plate in the flush-type shell conneclion assembly üat is greater_than the required
thiákness of lowest shell course, as determined by 5.6.3, 5.6.4, or A.4.1 (with joint efl¡c¡ency E = 1.0); and
3) the port¡on of the neck plate having a length equal to the üickness of the re¡nforc¡ng plate.
Re¡nforcing area prov¡ded shall be adequate for Des¡gn Conditions as well as Hydrostatic Test Conditions.
f) The width of üe tank-bottom reinforcing plate at the centerline of the opening shall be 250 mm (10 in.) plus the
combined nominal thickness of üe shell plate in the flush-connection assembly and the shell reinforc¡ng plate.
The th¡ckness of the bottom reinforcing plate shall be calculated by the following equaüon (see 5.7.7.6):
ln Sl units:
t,= ffitl^J-nc.cnwhere
¿á is üe m¡n¡mum th¡ckness of the bottom re¡nforc¡ng plate, in mm;
á is the vert¡cal height of clear opening, in mm;
ó is the hor¡zontal width of clear opening, in mm;
11 is the max¡mum des¡gn l¡quid level (see 5.6.3.2), ¡n m;
G is the specific aravity, not less than 1.0.
5-59
5,60 API STANoARD 650
Fullpeñetration
Notch as required to provideflush joint
All jo¡nts approximately90 degrees /.//"Botlon
Plale
mm ('10 in.)
(56€ Note 2)
Full-fillet weld
Bottom lrensitionplate for rhinimumarc dimension ofI¿l + 1500 mm (60 ¡n.)
125 mrr (5 in )
tJ.....- o J 7----.--..._,/Bottom reinforciñg phte / Buí-w€ld
2tr+ 25n
_tNozzle transition io
cirdr¡arflange
Sect¡on B-B Butt-weld
Centelineof connecl¡on
Figure 5.14-Flush-type Shell Connect¡on
c -<-.1Centerline of connecüon
15 in.) minShe¡l plate ¡n
flush connec'tion = fd
See Section C-C(Figure tl1 -cont¡nu6d)
Reinforcing plate = L
a, /€
,3/
One 6 mm (1/a") telltalehole in reinforcing plateat about mid,height
f, = 16 mm (5/s in.) min
<_ bl2------>-
/ "r"^ r,
t'150 mm (6 in.)m¡n
L
lE
l<+f..-------------. 1..-------- yylz arc otmengons'150 mm' 300 mm ' ,/
(6 in.)min (12 in.)min Bottom re¡nforc¡ng plate
(tQii;----- I
\,------------\ 75 mm=_-a.-ñ§:^)
Section A-A
Shell plate oflowest shellcouBe : f
VlELoEo TANrc FoR OIL §oRAGE 5-61
,- Ro¡rnd comer( when td> 40 mm (1r/, ¡n.)_ r,z___a
(«) mm [1rl, ¡n.l max) \,iV
Note 2)
Full-penetraüon weld
t,(See
Botlomreinforc¡ng
plate ¿d
Boltomfansitionplate t,
Aftemátivebutt-weld deta¡l
Botlorhtransit¡onplate t
1
Notol)4(j- tl.ngo p, tab¡es $8a and +8b
-",*['ri
125 mmts{5 in.ri
I
¿. = 16 mm (5/s ¡n.) m¡n
Nozzle transition
2td + 250 mm (10
Typ¡cal Deta¡l for Conneclions w¡th b = h
Ceniel¡ñe of
- _ nozl€ fange €nd
shell open¡ng
¿.= 13 mm (r/, ¡n.) m¡n
Back chipañd weld
Bottom plate
Eottomre¡nforc¡ng
plate tó
bt2
Round.
wnen tr= |rfm (11/, in.) |al,l0
'Ifn
/ 6 mi\(1/. ¡ñ.) m¡n
32 mm('1lla ¡n.) m¡n
tovI
(Soe Note 2)
Full-penet¡alonweld
< 30"
Centerlineof no¿le
nange
= 16 mm(%h.)m¡n
Noz¿e trans¡tion(see 5.7.8.4, ltem g)
Round corner
Bottom plate2¿d + 250 mm (10 ¡n.)
Nozle neck(see 5.7.8.4,
Item g)T'r, o
Flanges perfables $8a and S8b
Sectlon C4
Note 1: Flange weld s¡zes shall be the smaller of the ava¡lable hub materialfor rr.Note 2: Thickness of th¡nner plate jo¡ned 13 mm (1/2 in.) max¡mum.
Typ¡cál Detail for Coñneclions with ó > ,,
F¡gure 5.1¿t-Flush-type Shsll Gonnection (Cont¡nuod)
Round corner
WELDED TANKS FoR OtL SToRAGE
(See
t, = 16 mm (s/s ¡n.) min
Nozzle transition
2¿d + 250 mm (10
1Ñ(§ee Note 1) 4
Flanges per Tables S10a and 5-'l0b
Typ¡cal Deta¡l for Connections with b = h
t"s
l"Note 2)
Full-penetration weld
Bottomre¡nforc¡ng
plate ¿b
Bottomtrans¡tionplate a,
Bottomtransiüonplate t,
/'6mm(1/. ¡n.) min
32 mrn(1rl¿ in.) m¡n
Round @rner
Centerline ofnozzle lange andshell open¡ng
\
Altemativebutt-weld detail
125 mmF(s in.f>l
I Back chipand weld
b12
t"= 13 mm (r/, in.) m¡n
Bottom plate
Bottomreinforcing
plate tb
Round-
mm (1'/, in.) I
F0 rm (11/, h.) É{
tn
Full-penetrationweld
< 30" t = 16 mm (5/¡ in.)min
Centel¡neof noz¿e
flange
Nozzle neck(see 5.7.8.4,
Item g)
Nozzle transition(see 5.7.8.4, ltem g)
Round corñér
Bottom pláte2td + 250 mm (10 ¡n.)
1Ñ
Flanges per Tables 5-8a and 5-8b
Soction Cc
Note 1: Flange weld s¡zes shall be the smaller of the ava¡lable hub mater¡al for t .
Note 2: Th¡ckness of thinner plate jo¡ned 13 mm (1/2 ¡n.) max¡mum.
Typicál Detail for Connecüoñs w¡th b > h
F¡gure 5.14-Flush-type Shell Connection (Continued)
5-61
I(See Note 2)
5,62 API STANoARD 650
ln USC un¡E:
aza-r= rfu-fiJuc.ce
where
¡á ¡s the min¡mum thickness of the bottom reinforc¡ng plate, in inches;
l¡ is the venical height of clear opening, in ¡nches;
ó is the hor¡zontalw¡dth of clear opening, ¡n inches;
Il is the rnax¡rrum des¡gn l¡qu¡d level (see 5.6.3.2), in feet;
G is the specific gravity, not less than 1.0.
Ttrc minimum value of r¡shall be:
16 mm (5/8 in.) for HG< 14.4 m (48 ft)
17 mm (11/ro in.) for 14.4 m (48 ft) < flG< 16.8 m (56 ft)
19 mm (3/a in.) for 16.8 m (56 ft) < t1G < 19.2 m (64 ft)
g) The conoded thickness of the noz¿e neck and transition piece, ¡,¡ shall be not less than 16 mm (5/8 in.). Extemalloads appl¡ed to the connect¡on may requ¡re ¡rto be greater than 16 mm (5/e in.).
5.7.8.5 All materials ¡n the flush-type shell connection assembly shall conform to the requirements in Section 4. Thematerialof the shell plate ¡n the connection assembly, the shell reinforcing plate, the nozzle neck anached to the shell,the transit¡on p¡ece, and the bottom re¡nforc¡ng plate shall conform to 4.2.9 and F¡gure 4.1 for the respeciive thickness¡nvolved at the design metal temprature for the tank. The notch toughness of the bohing flange and the nozzle neckattached to the bolting flange shall be based on the goveming thickness as defined ¡n 4.5.5.3 and used in Figure 4.1.Addit¡onally, the y¡eld strengü and the tens¡le strength of the shell plate at the flush-type shell connection and üeslrcll reinforcing plate shall be equal to, or greater than, the yield strength and the tens¡le súength of the adjacentlowest shell course plate material.
5.7.8.6 The nozzle transition between the flush connection in the shell and the c¡rcular pipe flange shall be des¡gnedin a manner cons¡stent w¡th the requirements of th¡s standard. Where th¡s sl,andard does not cover all deiails of designand construction, the Manufacturer shall provide details of design and construction that úll be as safe as the deta¡lsprovided by this standard.
5.7.8.7 Where anchoring dev¡ces are requ¡red by Annex E and Annex F to resist shell uplift, the devices shall bespaced so that they w¡ll be located ¡mmediately adjacent to each side of the re¡nforc¡ng plates around the opening.
5,7.8.8 Adequate provision shall be made for free movement of connected p¡ping to minimize thrusts and momenEappl¡ed to the shell connecüon. Allowance shall be made for the rotation of the shell connection caused by therestra¡nt of the tank bottom-to-shell expansion from stress and temperature as well as for the thermal and elast¡cmovernent of the piping. Rotation of the shell connection is shown in Figure 5.15.
5.7.8.9 The foundation ¡n the area of a flush-type connect¡on shall be prepared to support the bottom reinforcingplate of the connection. The foundat¡on for a tank rest¡ng on a concrete ringwall shall proüde uniform suppon for boththe bottom reinforc¡ng plate and the remain¡ng bottom plate under the tank shell. D¡trerent methods of supponing thebottom reinforcing pate under a flush-type connecl¡on are shown ¡n F¡gure 5.13.
API Sr ND^RD 650
ln USC units:
h2h.,. = L+L t|-O + C,t'u l¿,ooo' 3 to''
where
rá ¡s the m¡nimum thickness of the bottom re¡nforc¡ng plate, ¡n ¡ncfies;
á is the vertical he¡ght of dear opening, ¡n ¡nches;
á ¡s the horizontal údth of dear opening, in ¡nches;
11 ¡s the maximum des¡gn l¡qu¡d level (see 5.6.3.2), ¡n feet;
c is the specmc gravity, not less than 1.0.
The minimum value of l¡ shall be:
16 mm (5/8 ¡n.) for ¡/c < i4.4 m (48 ñ)
'f 7 mm (11116 ¡n.) for't4.4 m (48 ft) < HG < 16.8 m (56 ñ)
19 mm (si4 ¡n.) for '16.8 m (56 fr) < ¡ic < 19.2 m (64 ñ)
g) The mnoded th¡ckness of the nozzle neck and transit¡on p¡ece, ,,, shall be not less than 16 mm (5/8 ¡n.). Extemalloads appl¡ed to the connecfion may require ¡,, to be greater than tO mm (5/8 ¡n.).
5.7.8.5 All materials in the flush-type shell connedion assembly shall conform to the requirements in Sec{¡on 4. Thematerial ofthe shell plate ¡n the conneclion assembly, the shell re¡nforc¡ng plate, the nozzle neck attached to the shell,lhe trans¡t¡on p¡ece, and the bottom re¡nforc¡ng plate shall confom to 4.2.9 and F¡gure 4.1 for the respeclive thickness¡nvolved at the des¡gn metal temperature for the tank. The notch toughness of the bolting fange and the nozzle neckattached to the bolt¡ng flange shall be based on the goveming th¡ckness as defned in 4.5.5.3 and used ¡n F¡gure 4.1.Add¡tionally, the y¡eld strength and the tens¡le strength of the shell plate at the flush-type shell connecl¡on and theshell reinforcing plate shall be equal to, or greater than, the y¡eld strength and the tensile strength of the adiacentlowest shell course plate material.
5.7.8.6 The nozzle transiüon between the flush conneclion in thé shelland the c¡rcular pipe f,ange shall be designed¡n a manner @ns¡stent with the requirements of th¡s standard. Vvhere th¡s standard does not cover all deta¡ls of des¡gnand constuct¡on, the Manufac{urer shall provide deta¡ls of design añd construc-tion that r r¡ll be as safe as the deta¡lsprovided by th¡s standard.
5.7.8.7 Vvhere anchoring devices are requ¡réd by Annex E and Annex F to resisl shell upl¡ft, the devices shall bespaced so that they will be located immed¡ately adjacent to each side of the re¡nforc¡ng plates around the open¡ng.
5.7'8.8 Adequate provision shall be made for free movement of connected piping to m¡nim¡ze thrusts and momenbapplied to the shell connecl¡on. Allowance shall be made for the rotat¡on of the shell @nnec{on caused by therestra¡nt of the tank bottom-to-shell expansion from stress and temperature as well as for the thermal and elaslicmovement ofthe p¡p¡ng. Rotation ofthe shell connect¡on is shown in F¡gure S.1S.
5.7.8.9 The foundat¡on ¡n lhe area of a llush-type connecl¡on shall be prepared to support the bottom re¡nforcing
i _ plate of the connecl¡on. The foundat¡on for a tank resüng on a conqete ringwall shall proüde unifom support for bothlhe bottom reinforc¡ng plate and the rema¡n¡ng boftom plata under the tank shell. D¡fferent methods of supporting thebottom re¡nforcing plate under a flush-type conneclion are shown ¡n F¡gure 5.13.
WELDED TANxs FoR OtL SToRAGE 5-63
lnitial shell radius = R
Shell radius=R+AR
75 mm (3 in.) min
Details A and B)lnside diameter of shell
Notch to suit bottom reinforcing plate
lnside of shell atcenterline ofopening
Deta¡l A Detail B
Oetails of Notch in Ringwall
F¡gure 5.1s-Rotation of Shell Connection
5,7.8.10 Flush-type connecüons may be ¡nstalled using a common reinforcing pad; however, when this constructionis employed, the minimum distance between nozzle centerlines shall not be less than 1.51b1 + b¿ + 65 mm (21lz in.)],where 4 and bz are lhe widths of adjacent openings, or 600 mm (24 an.), whichever is greater. The w¡dth of eachopening, ó. shall be obta¡ned from Table 5.12a and Table 5.12b for the respective nominal flange size. Adjacent shellflush-type connect¡ons that do not share a common reinforc¡ng plate shall have at least a 900 mm (36 ¡n.) clearancebetween the ends of their reinforc¡ng plates.
5.7.8.11 All longitud¡nal hrtt-welds in the nozzle neck and transition p¡ece, if any, and the f¡rst circumferential butt-weld in the neck closest to the shell, excluding neck{o-flange weld, shall rece¡ve 100 o/o rad¡ographic examination(see 8.1). The nozzle-to-tank-shell and reinforcing plate welds and the shell-to-bottom re¡nforcing plate welds shall beexam¡ned for the¡r complete length by magnet¡c particle exam¡nation (see 8.2). The magnetic part¡cle exam¡nationshall be peformed on the root pass, on every '13 mm (1/2 ¡n.) of depos¡ted weld meial wh¡le the welds are made, andon üe completed welds. The completed welds shall also be visually examined. The examinaüon of the completedwelds shall be performed after stress-relieving but before hydrostatic tesfng (see 8.2 and 8.5 for the appropr¡ateinspection and repa¡r criteria).
try+ 300 mm (12 ¡n.) min,except as lim¡ted by
curvature of foundat¡on(see Detail B)
Reinforcing plate
Height of bend¡ng¡n shell varies with
tank rad¡us andthickness
I\_->lnitial cénterline
of connection
Anole ofrolaÚon
Centerline ofconnection after
elastic movementof shell
API STANDARD 650
5.8 Shell Attachments and Tank ApPurtenances
5.8.1 ShellAttachments
5.8.1.1 St|ell anachments shall be made, inspected, and removed in conformance with section 7.
a) pennanent attachments are items welded to the shell üat w¡ll rerna¡n while üe tank ¡s ¡n its intended sérvice.
These ¡nclude items such as w¡nd girders, sta¡rs, gaug¡ng systems, davits, walkwa)ls, tank anchors, supports for
intemal items such as heating co¡ls and other Op¡ng suppor6, ladders, float¡ng roof supports welded to the shell,
exterior pip¡ng supports, grounding clips, ¡nsulation r¡ngs, and electrical conduit and fixtJres. ltems installed above
the max¡mum l¡quid level of the tank are not permanent attachments.
b) Temporary attachments are items welded to the shell that w¡ll be removed prior to the tank being comm¡ss¡oned' into its ¡niended serv¡ce. fhese inctude items such as al¡gnment clips, fming equipment, stab¡l¡zers, and lifting
lugs.
S.g.1.2 When attachments are made to shell courses of mater¡al in Group lV, lVA, V, or Vl, the movement of the
shell (part¡cularly the movement of the bottom co-rrse) under hydrostat¡c load¡ng shall be cons¡dered, and the
attachments shall meet the follow¡ng requirements:
a) permanent attachments may be welded d¡rectly to the shell w¡th fillet welds having a maximuln leg d¡mension of
13 mm (1/z in.). The edge oi any permanent anachment welds shall be at least 75 mm (3 in.) from the horizontal
joints of the sñell and ai lmst íSb mm (6 in.) from the vert¡caljo¡nts, ¡nsert-plate jo¡nts, or reinforc¡ng-plate fillet-welds. permanent attachment welds may cross shell horizontal or vertical butt welds providing the welds are
cont¡nuous within these limits and tfre angte of inc¡dence between the two welds ¡s greater than or equal to 45
degrees. Additionally, any splice weld in the permanent anachment shall be located a minimum of 150 mm (6 ¡n.)
froit any shell weld unlés ihe splice weld is kept from intersectjng the shell weld by acceptable rnodmcaüons to
the attachrnent.
b) The welding and ¡nspection of permanent attachrnents to these shell courses shall conform to 7.2.3.5.
c) Temporary attachments to slEll courses shall preferably be made pr¡or to weld¡ng of the shelljoints. Weld spacing' for témpoiary anachments made after welding of the shelljo¡nts shall be the same as that requ¡red for permanent
attach;En§. Temporary attachments to shell courses shall be removed, and any resuhing damage shall be
repa¡red and ground to a smooth profile.
. 5,8.2 Bottom Connections
connecüons to the tank bottom are perm¡tted subject to agreement between the Purchasef and the Manufacturer
w¡th respect to deta¡ls that provide strength, t¡ghmess, and ú¡lity equal to the details of shell connections spec¡f¡ed in
this standard.
5.8.3 Cover Plates
5.8.3.1 Unreinforced openings less than or equal to NPS 2 pipe s¡ze are pemissible in flat_cover plates without
increas¡ng the cover plaie thic-kness it the edgea of the open¡ngs are not closer to the center of the cover plate than
one-fourtñ üre heightbr diameter of the opening. Requirements for open¡ngs N!! ? qtpe sizg ald smáller üat do not
safsfy the locatioñ requ¡rement and fof larger reinforced openings are given in 5.8.3.2 through 5.8.3.4.
5.8.3.2 Re¡nforced openings in the cover plates of shell manholes and flush-type clean outs shall be limited to one-
half the diameter of the manhole or one-háfi the least dimension of the flush-type clean out open¡ng but shall not
exceed NPS 12 pipe s¡ze. The re¡nforcement added to an oPen¡ng may be a f9lnforclng plate or an increased
thickness of the cóver plate, but in either case, the reinforcement shall provide an added reinforc¡ng area no less than
the cutout area of the opening ¡n the cover plate.
WELDED TANKS FoR OrL SToRAGE
A cover plate with a nozzle attachrnent for product-m¡x¡ng equ¡pment shall have a thickness at least 1.4 times greaterüan the thickness required by Table 5.3a and Table 5.3b. The added thickness (or pad plate) for replacement of theopen¡ng cutout ¡n the cover plate shall be based on Table 5.3a and Table 5.3b. The 40 % increase in th¡ckness withina radius of one d¡ameter of the open¡ng may be included as part of the area of replacement required. The m¡xer-nozzle attachment to the cover plate shall be a full-penetrat¡on weld. The manhole bohing-flange th¡ckness shall notbe less than'1.4 tirnes the thickness required by Table 5.3a and Table 5.3b. The manhole nozzle neck shall bedes¡gned to support the mixer forces w¡th a minimum thickness not less than the requirements of Table 5.4a andTable 5.4b without compar¡son to the increased bolting-flange th¡ckness noted ¡n this section.
5.8.3.3 When cover plates (or blind flanges) are required for shell nozzles, the minimum thickness shall be thatgiven for flanges ¡n Table 5.8a and Table 5.8b. Reinforced openings in the cover plates (or blind flanges) of shellnozzles shall be limited to one-ha[f the diameter of the nozzle. The reinforcement added to an opening may be anadded pad plate or an increased th¡ckness of the cover plate, but ¡n either case, the reinforcement shall prov¡de anadded reinforcing area no less than 50 o¿ of the cutout area of the open¡ng ¡n the cover plate. Mixer nozzles may beattached to cover plates.
5.8.3.4 Openings in the cover plates of Rush-type cleanout fittings shall be located on the vert¡cal centerline of thecover plate and shall be ¡n accordance w¡th 5.8.3,1 and 5.8.3.2. Adequate provis¡ons should be made for freemovement of connected p¡ping to minimize thrusts and moments on the cover plate to 2225 N (500 lbs) and 60 N-m(50O ft-lbs). Analysis or load leak test may be used to accept greater loads or moments.
5.8.3.5 Shell manhole covers shall have two handles. Those covers weighing more than 34 kg (75 lb) shall beequipped with e¡ther a hinge or davit to faciliiate the handl¡ng of the manhole cover plate. The dav¡t support arm shallnot be welded directly to the shell without a reinforcing plate.
5.8.4 Roof Manholes
Roof manholes shallconform to Figure 5.16 and Table 5.13a and Table 5.13b. The effects of loads (other than normalpersonnel access) applied at the roof manhole and supporting roof structure shall be considered. Examples of suchloads may ¡nclude fall protect¡on anchorage, ho¡st¡ng, or personnel retr¡eval. The roof structure and plate around themanhole shall be reinforced as necessary.
5.8.5 Roof Venting
5.8.5.1 Tanks des¡gned in accordance with this standard and having a f¡xed roof shall be vented for both normalcondiüons (resultjng from operat¡onal requ¡remenB, ¡ncluding max¡mum f¡lling and emptying rates, and aünospherictemperature changes) and emergency conditions (resutting from exposure to an e)dernal fire). Tanks with both a f¡xedroof and a float¡ng roof sat¡sfy these requirements when they comply w¡th the circulation venting requirements ofAnnex H. All other tanks designed in accordance with this standard and hav¡ng a f¡xed roof shall meet the ventingrequirements of 5.8.5,2 and 5.8.5.3.
5.8.5.2 Normal venting shall be adequate to prevent internal or extemal pressure from exceeding the conespondingtank design pressures and shall meet üe requiremenE specif¡ed in API 2000 for normal venting.
5.8.5.3 Ernergency veming requ¡rernents are satisfied if the tank is equipped with a weak roof-to-shell attiachment(Íiangible joint) in accordance with 5.10.2.6, or if the tank is equ¡pped with pressure relief devices meeüng therequ¡rernents spec¡Fred ¡n API 2000 for ernergerrcy venüng. When pressure rd¡ef devices are used to saüsly theernergency venting requ¡rernenb, they shall ach¡eve the flow rates specmed in API 2m0 without exceed¡ng the followinglimits on intemal pressure.
a) For unanchored tanks, the pressure rel¡ef devices shall be adequate to prevent ¡ntemal pressure from exceed¡ngüe tank design pressure as determined ¡n F.4.1 (subject to the l¡mitat¡ons in F.4.2 and F.4.3, as appl¡cable). lncalculating l¡mitations per F.4.2, use M= 0.
5-66 API STANoARo 650
Dimens¡ons in mill¡meters
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column 9
Size ofManhole
D¡ameterof Neck
ID
Diameterof Cover
PlateD¿
Diameterof BoltC¡rcle
Dp
Numberof Bolts
Diameter ofHole ¡n Roof
Plate orDiameier of Gasket Reinforc¡ng
_-..........i-Platelnside Outs¡de Dp
OutsideDiarneter ofReinforc¡ng
PlateDp
500 500 660 597 16 s00 660 524 1050
600 600 162 699 20 600 762 625 1150
a p¡pe may be used for neck, trovid¡rE üe m¡n¡mum nom¡nal wall h¡c*ness is 6 mm (/D and Dp shall be adjusted accordirEly.)
NOTE See Folfe 5,18.
Table 5.13a-Dimens¡ons fol Roof Manholes (Sl)
Table 5.13b--D¡mensions for Roof Manholes (USC)D¡mens¡ons in inches
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 Column 7 Column 8 Column I
Size ofManhole
Daameterof Neck
,
D¡ameterof Cover
PlateD¿
Diameterof BoltC¡rcle
Ds
Numberof Bolts Diameter of Gasket
D¡ameter ofHole ¡n Roof
Plate orRe¡nforc¡n9
PlateDp
outsideD¡ameter ofRe¡nforc¡ng
PlateDplns¡de Outside
20 20 26 23112 16 20 26 2o5lB 42
24 24 30 27112 20 24 30 24518 46
a P¡pe may be used for nec*, provid¡rE fie min¡mum nom¡nal !¡!all lh¡ckr¡ess is 1/. in. (lDand ,/ shallbe adjus¡ed acco.dingly.)
NOTE See Figure 5.18.
b) For anchored tanks, except those designed to F.1.3, the pressure relief devices shall be adequate to prevent
intemal pressure from exceeding the tank design pressure as determined ¡n F.4.1 (subject to the limitaüons ¡n
F.4.3, as appl¡cable).
c) For tanks designed to F.1,3 (anchored ianks), the pressure relief devices shall be adequate to prevent internal
pressure from exceeding the design pressure specified by the Purchaser.
S.8.S.4 The fill¡ng and empty¡ng rates are specified on the Data Sheet, Line 7. See the Data Sheet, Table 3 for
venting devices, wh¡ch shall be specif¡ed by the Purchaser and verif¡ed by the Manufacturer.
5.8.5.5 All free vents shall be provided w¡th conosion-res¡stant coarse-mesh b¡rd screens of a maximum opening
s¡ze of (19 mm [3/4 ¡n.l nominal open¡ng). lt ¡s recomrnended that in areas where snow drifting or ic¡ng may be an
¡ssue, special attenüon to vent deta¡ls (iuch as profile, d¡ameter, capac¡ty, alrangemert, or ¡ncreased screen s¡ze)
should be made. ln these situat¡ons the Purchaser shall spec¡ry modmed vent¡ng requirements based on anüc¡pated
needs for a spec¡f¡c environment. The smallest dimension of the open¡ng in any mesh used for bird screen is the
governing size for the open¡ng.
5.8.5.6 Flanged roof nozzles shall conform to Figure 5.19 and Table 5.'l4a and Table 5.14b. Sl¡p-on nanges and
weld neck flañges shall conform to üe requiremenb of ASME 816.5 for Class 150 plate-ring flanges shall conform to
wELDEo TANKS FoR OrL SToMGE 5,67
1.5 mm (1/16 in.)th¡ck gasket =>
Reinforcing plate \I
f 6 mm (1/. in.) I| ------n
16 mm (5/s in.)diam€ter rod
Section A-A-Roof Manhole W¡th Re¡nforc¡ng Plate
Base For Rool ¡lanhole W¡thout Re¡ñforcing Plate
F¡gure 5.16-Roof Manholes (see Table 5.13a and Table 5.13b)
16-mm (s/s-in.) diameter bolts iñ 20-mm (3¿ ¡n.)diameter holes (see Table 5-13a and fable $13tfor ñurfiber of bolts; bolt holés shall straddle
Altemaüve Neck-to-Roof-Plate Jo¡nt
Ó ,somm(6in.)
|
r-----i-----r------ó | 0,, 1'tl in.¡ -,". ptate
150 mm (6 in.) :tl. Y ¿-:-::- /
\ --- r- ,/t
: Axis alwavsI vélrcál
6 mm (1/. in.) |I
rAlternative Flañge Detail
,ñ --------------+]
+t_
API STANoARD 650
all of the dimensional requ¡rements for sl¡p-on weld¡ng flanges with the excepüon that ¡t is acceptable to omit thee)«ended hub on the back of the sl¡p-on or weld neck flanges. Raised face flanges shall be provided for nozzles withattached p¡ping. Flal face flanges shall be provided for roof nozzles used for the mount¡ng of tank accessories.
5.8.5.7 Threaded roof nozzles shall confotm to F¡gure 5.20and Table 5.15a andTableS.l5b.
5.8.6 Rectangular Roof Openings
5.8.6.1 Rectangular roof open¡ngs shall conform to Figure 5.17 and Figure 5.18 and/or this section. The effects ofloads (other than normal personnel access) appl¡ed at the roof opening and supporting roof structure shall be
cons¡dered. Examples of such loads may include fall protection anchorage, hoist¡ng, or personnel retrieval. The roof
structure and plate around the opening shall be reinforced as necessary.
Table 5.14a-D¡mensions for Flanged Roof Nozzles (Sl)D¡mens¡ons in m¡ll¡meters
Column 1 Column 2 Column 3 Column 4 Column 5
NozzleNPS
outside Diameterof Pipe Neck
D¡ameter of Hole ¡n RoofPlate or Re¡nforc¡ng Plate
Dp
M¡n¡mum Heightof Nozzle
Hn
outs¡de Diameter ofReinforcing Platé
Dp
1112 48.3 50 't50 125
2 60.3 65 150 115
3 88.9 92 150 225
4 I 114.3 120 150 215
6 168.3 170 150 375
I 219-1 225 '150 450
10 213.O 280 200 550
12 323.8 330 200 600
a Reinforcing plates are not required on nozzles NPS 6 or snaller but rnay be used if desifed'
NOfE Se€ F¡g[e 5.19.
5.8.6.2 The cover plate thickness and/or structural support shall be designed to l¡mit max¡mum fiber stresses in
accordance with th¡s standard, however, cover plate thickness shall not be less than 5 mm (r/lo in.). ln addition to
other expected design loads, consider a 112 kg (250 lb) person standing in the center of the installed/closed cover.
The designer shall cónsider wind in the design of ninged openings and how rernoved covers w¡ll be handled without
damage (adequate rigidity).
5.8.6.3 Rectangular open¡ngs, other than shown in Figure 5.17 and F¡gure 5.18, alg 9p9n¡ngs larg:r.than ind¡cated
inati Oe Oesignel ny án en-gineer experienced ¡n tañk design in accordance w¡th this standard. Hinqed coves
prescr¡H in Éigure á.t a mafnot oe uied on roofs designed tó contain internal Pressure. Flanged covers prescribed
in Figure s.t7 ñay not be u;ed on tanks with internal pressures (acting acros§ üe.cross secÜonal area of the tank
roo¡-that exceed tie weight of the roof plates. This section appl¡es only to fixed steel roofs.
wEroEo TAN(S FoR OrL SToRAGE s-69
Table 5.14b--D¡mensions for Flanged Roof Nozzles (USC)
Table 5.1sa-Dimens¡ons for Threaded Roof Nozzles (Sl)
D¡mens¡ons in ¡nches
Column 1 Column 2 Column 3 Column 4 Column 5
NozzleNPS
outs¡de D¡ameterof PiPe Neck
Diam€ter of Hole ¡n RoofPlate or Re¡nforc¡ng Plate
Dp
M¡nimum Heightof Nozzle
Hp
Outs¡de D¡ameter ofRe¡nforcing Platea
Dp
1112 'r.900 2 6 5
2 23ta 2112 6 1
3 3112 3s/s 6 9
4 4112 45lB 6 11
6 6s/8 63/1 6 '15
B 8s/8 81lB 6 18
10 103/{ 1'1 B 22
12 12311 13 8 24
a Reiffqcing plates are r|ot required on nozzles NPS 6 or smaller hrt may be used if des¡red.
NOTE See F¡$re 5.19.
Dimens¡ons ¡n mill¡meters
Column 1 Column 2 Column 3 Column 4
NozzleNPS
CouplingNPS
D¡ameter of Hole ¡n Roof Plateor Reinforc¡ng Plate
Dp
Outs¡de D¡anreler ofRe¡nforc¡ng Plateá
Dq
3lt 3lt 36 100
1 1 44 110
1112 1112 60 125
2 2 76 175
3 3 105 225
4 4 135 215
6 6 192 375
8 I 250 450
10 10 305 550
12 12 360 600
a Reinlorcing plates are not requ¡red oo rpz¿es NPS 6 or srmller b|.f may be us€d ¡f desired.
NOTE See F¡gue 5.20.
5-70 API SIANDARO 650
Dimens¡ons ¡n ¡nches
Column 1 Column 2 Column 3 Column 4
NozzleNPS
Coupl¡ngNPS
Diameier of Hole ¡n Roof Plateor Re¡nforc¡ng Plate
Dp
outs¡de D¡ametef ofRe¡nforcing Platea
Dp
3lt 3lc 111i6 4
1 1 123h2 41lz
11lz '1112 211h2 5
2 2 3 1
3 3 41la I4 4 511h2 1'l
6 6 111h2 15
I 8 9?/s 18
10 10 12 22
12 12 14111 24
a Reiffo.c¡ng plates are not requied on mzzles NPS 6 or sllaller br¡t may be l§€d if des¡red.
NOTE See F¡gwe 5.20.
Table 5.1sb-D¡mens¡ons for Threaded Roof Nozzles (USC)
5.8.7 Water Drawoff Sump§
Water drawoff sump6 shall be as speciñed ¡n F¡gure 5.21 and Table 5.16a and TaUe 5.16b unless othenrvise specified bythe Purchaser.
5.8.8 ScaffoldcableSupport
The scaffold-cable support shall conform to F¡gure 5.22. Where seams or other attachments are located at the center
of the tank rool the scatrold support shall be located as close as possible to the center.
5.8.9 ThreadedConnect¡ons
Threaded p¡p¡ng connections shall be female and tapered. The threads shall conform to the requ¡rements of ASME
81 .20.1 for tapered pipe threads.
5.8.10 Plaúoms, Walkways, and Sta¡ruays
a) Plaúorrs, walkwa)s, and staimays shall be ¡n accordance with Table 5.17, Table 5.18, Table 5.19a, and Table
5.19b, and osHA29 cFR 1910, Subpart D, or equ¡valent national safety standard and the requ¡rements here¡n,
except as noted here¡n.
b) For examples of acceptable deta¡ls, see Process lndustry Practices standard details PIP STF05501, PIP
STF05520, and PIP STF05521 (see www.p¡p.org).
c) Unless decl¡ned on the Data Sheet, Line 24, a roof edge landing or gauger's daÚorm shall be prov¡ded at the top
of all tanks.
wEroEo TANKS FoR OtL SfoFl GE 5-71
Griñd flush
1.5 mm (146 in )thick gasket
Cover 5 mm (346 in.) lh¡ck m¡n¡mum
5 mm (346 in.) galv.
38 mm (1.5 in.) x 38 mm (1.5 ¡n.) x 6 mm (t/¿ ¡n.) lab
Sect¡on B€
6 mm (1á ¡n.) reinforc¡ng plat€, when required. See Not6 4.
_>Y,*?
Sec{¡on A.A Typical
Typicál
100 mm (4 in.) m¡n¡mum
75 mm (3 in.) x 10 mm (3/s ¡n.)flañge
oooooooooo
Neck 6 mm (% in.) hick m¡n.
Except for hañdle§, coverplate not shown.
'V Note 3
:--i::::--=:--¿--:
Figure 5.17-Rectangular Roof Openings with Flanged Covers
(10 iñ.) max
*l [- 75 mm (3 ¡n ) typ¡cál
mm(3n)mar-
*l150 mrn(6 ¡n.)
512 API STANDARo 650
ii
mmmax
150 mm(6 in.)
5 mm (3/16 in.) typical
16 mm (5/s ¡n.) d¡ameter rod handle, I placefor 900 mm (3 ñ) or less cor,/Er, 2 places att/.-poinls for largef op€n¡ngs
Neck 6 mm (1/4 in.) th¡ck min.
I 50 mm (2 in.) typical
5mm(3/16 in )
Fabncate hinges from NPS 1
SCH 40 pipe and 22 mm (18 ¡n.) rod,m¡ñimum 2 each, maximum 600 mm(2 ñ) O.C., equally spaced.
1800(6 fr)
Prov¡de 2 lock tabs for opeñingslarger than 900 mm (3 fl)
l'- rzs,n- (s ¡n')
F¡gure s.l8-Rectangular Roof Openings with Hinged Cover
5.8.11 Other Appunenances and Attachments
5.8.11.1 Floaüng suct¡on lines shall be provided when specif¡ed on tlle Data Sheet, Table 4. Floaüng suction lines
us¡ng rigid articulated (hav¡ng one or more swingjo¡nts) p¡pe shall be designed to travel in a vertical plane and prevent
damage to the float¡ng roof and the suction l¡ne through its design range of travel. These l¡nes shall be des¡gned sothat the venical plane ¡s as close as possible to, and in no case greater than 10 degrees otr, a radial line from the tankcenterl¡ne to the nozzle. Adjustments shall be made to clear ¡ntemal stmctures.
5.8,11.2 lnlet dift¡sers shall be prov¡ded when specified by üe Purchaser or the floaüng roof manufaclurer.Tradiüonal diffuser siz¡ng to limit exit velocity to 3 fr/sec prov¡des protecl¡on for tank ¡ntemal components and reduces
stat¡c electr¡city build up due to splashing and m¡st¡ng however does not l¡mit static electric¡ty bu¡ld up ¡n tanks due tohigher velocity product flow in external ¡nlet and olrüet pip¡ng. See API 2003. Requirernents shall be included ¡n theData Sheet (table 4 or Table 5).
6mm(1L ¡n.)min.
mm (346 ¡n.) m¡nimum th¡d( cover
Elevation
50 mm (2 ¡n.)
250 mm(10 in )
|-soomm (3ñ)max-l
WELDEo faN(s roR OtL SToRAGE 5-73
Plain or raised-facesl¡pon welding, welding-neck,or plate ring ñange
(See note)
DP
' Roof plate
Standard-we¡ght l¡ne pipe
Nozzle w¡th Reinforc¡ng Plate Base for Nozzle without Re¡nforcing Plate
Figure s.1g-Flanged Roof Nozzles (see Table 5.14a and Table 5.14b)
Axis always vertical(See note)
rfi (/¡ in.
Roof plate
Pipe coupling
DP
Nozzle with Rs¡nforciñg Plato Nozzle w¡lhout Réinforcing Plate
Figure s.2o-Threaded Roof Nozzles (see Table 5.15a and Table 5.15b)
lñtemalpipe
6 mm (t/. inalf,a3
f, K._.,.Detáils al-a,! backup ba.
(allale acceplabl€) to f,ange
100 mm (4 ¡n. DetailSand cushaon c,ord Detail b Deta¡l c Deta¡l d
NOTE The eredim procedue shall be p€rloíned by one of the following rnethods or by an aheÍ¡ate des¡gn approved by a gorage TankEng¡neer:
a) For stmps being placed ¡n úle foundarbo berore bomrn placemert, üe sump shall be placed ¡n posilbn with at lea§ 1Cl0 mm (,t in.) ofthoroughty compacted sand, or oüe. suitable f¡ll rnateritl, arouod üle su.rp. The sump úleo shall be u,elded to the bdtom.
b) For sumps being placed ¡n ihe foundatbn afrer botorn placement, suÍaieot boüorn plate shall be reÍpved to allow for the sump to beplaced in positbn wiül at least 100 mm (,1 ¡n.) of üro.oughly cornpcted sand, or oft€r suitable fill matefial, a.oünd ú|e surp. The suÍpshall úlen be welded !o lhe boüor¡.
»-q a )-". 7 -v\ n6 mm ('l§§Gmm c/. ¡rRV8 mm e/,6 ¡W
_______________¡{
150 mm ñ<- Tank shetl
Figure s.21-Drawoff Sump (see Table 5.16a and Table 5.16b)
N ,a"-R,T\.--f
AltgmaliveNeck.{o¡ooFlate
Jolnt
Roof plate
5-14 API SÍANDARo 650
6 mm (r/a in.) plate
6 mm (r/¡ in.)
-rI
l5O mm (6Schedule 40
pipe (see note)
8 mm (3/!6 in.)
10 mm (3/s ¡n.)fomed plate
6 mm (rilin.
mm (5r/¡ in.) Tañk roof
230 mm (9 ¡n.) diameter
Figure s.zz-Scaffold Cable Support
Table 5.1oa-Dimensions for Drawoff Sumps (Sl)
Table 5.1Gb-Dimens¡ons for Drawoff Sumps (USC)
NPS
Diameter ofSump
in.A
Depth of Sümp¡n.B
Disiance froírcerüer Pipe lo Shell
ñc
Th¡ckness ofPlates ¡n Sump
in.I
Minimumlntemal
P¡pe Th¡ckness¡n.
Minimum Nozzleñleck Thickn€ss
in.
2 610 (24) 12 3112 J/15 0.218 0.2'18
3 910 (36) 18 5 3ta 0.250 0.300
4 1220 148\ 24 63/1 3tB 0.250 0.337
6 1520 (60) 36 8112 1l$ 0.2 50 o.432
NOTE See F¡gure 5.19.
5.8,11.3 lf requ¡red by the Purchaser, grounding lugs shall be prov¡ded in the quantiqr specified on the Data Sheet,Table 4, and comply w¡th F¡gure 5.23. The lugs shall be equally spaced around the base of the tank. Prov¡de am¡n¡mum of four lugs. The suggested max¡mum lug spacing is 30 m (100 ft).
NOTE Tanks that rest directly on a foundat¡on of soil, asphalt or concrete are ¡nherently grounded for Purposes of dissipation ofelectros¡auc charges. The addit¡on of grounding rods or sim¡lar devices will not reduce ú|e házard assochted with electostaticcharges ¡n the stored producl. API Recommended Practice 2m3 conta¡ns addit¡onal information about tank grounding issues asrt ell as comments aboul lightn¡ng protect¡on.
5.8.1f .4 All non-circular miscellaneols pads shall have rot¡nded comers with a minimum rad¡us of 50 mm (2 ¡n.).
Pads that rrust cover shell seams shall be Prov¡ded with a 6 mm (1ft ¡n.) telltale hole (see 5.7.3 4).
NPS
D¡ameter ofSumpmmA
Depth of SumpmmB
Distance fromCenier P¡pe to Shell
mc
Th¡ckriess of irin¡mumPlates ¡n Sump lntemal
mm Pipe tüid«pss,mm
M¡n¡mum NozzleNeck Thickness
mm
2 610 300 '1 .1 I 5.54 5.54
3 910 450 10 6.35 1.62
4 1220 600 2.1 10 6.35 8.56
6 1520 900 2.6 11 6.35 10.97
NOTE See Figure 5.19.
WETDED TANKS roR O[ SfoRAGE 5-75
Table 5.17-Requirements for PlaÚorms and Walkways
All parts shall be made of metal
TheminimumW¡flhofthewalkwayshallbe610mm(24in.),afrefmakingadjustmentsatallPfoject¡ons.
Flooring shall be made of grat¡ng or nomliP rnaterial
The he¡ght of the top ra¡ling above the ffoor shall be 1070 mm (42 in.).4
The m¡nimum he¡ltf of the toeboard shall be 75 mm (3 ¡n.).
The maximum space beMeen the top of the floof and the bonom of the toeboard shall be 6 mm (1/4 ¡n.).
The he¡ght of rhe midra¡l shall be approximately one-half the distance from lhe top of lhe walkway to the toP of the ra¡ling.
The maximum distance between rail¡ng Posts shall be 24m mm (96 in ).
The comoleted structufe shall be capable ol supponing a moving concentfated load of 4450 N (1000 lbf), and the
r'u"oiáii ítruárá s¡rál oe capaur dt witr'standirig a bád of 9oo N (2oo lbO applied ¡n any direclion at any point on the
Handrails shall be on both sk es of the plaÚofm bul shall be disconünued where necessary for access.
At handra¡l openings, any space wiJer üan 150 mm (6 ¡n.) between the tank and the plaÚom should be floored.
A tank runway that extends ftom one paft of a tank to any part of an aqjacernbnk, to the ground, of to anothef stfucture
;hrtt be;Jpp'"rled * that free relaüv¿ movement of the siruclures joinedty the runwa{. ryjry*:Ilt-T1y.f^- ."^"".áráÉiLlJ¡,
nm anachment of the runwaY to one tank and the use of á slipjoint a[the po¡nt of contact between lhe
runwaj and the-other tank. (This method perníits either tank to senle or be disrupted by an explosion without the other
a fh¡s handra¡l heigatt is required by OSHA specifications.
Table 5.1 8-Requirernents for Stain¡vays
1. All pans shall be made of metal.
2. The minimum width of the sta¡rs shall be 710 mm (28 ¡n.).
3. The max¡mum anglea of the stairway with a horizont¿ll l¡ne shall be 50 degrees.
4.The m¡n¡mum width of the sta¡r reads shall be 200 mm (8 ¡n.). (The sum of twice the rise of the sta¡r treads Plus the run
ldefined as the horizontal distance between the noses of successive read piecesl shall not be less than 610 mm [24¡n.l or more than 660 mm [26 in.l. Rises shall be uniform throughot t the he¡ght of the staiMay.l)
5. Treads shall be made of grating or nonsl¡p material
6.The top ra¡ling shalljo¡n the plaúom handra¡l wittDrn ofiset, and the heighl measured vertically from tread level at thenose ofthe tréad shall be 760 mm to 860 mm (30 in. to 34 ¡n.).
7. The max¡mum distance be¡^,een rail¡ng posts, rneasured along the slope of the railing, shall be 24@ mm (96 ¡n.).
B.The completed structure shall be capable of supponing a moving concentrated load of 4450 N (f000 lbD, and thehandrail iúuclure shall be capable of withsranding a load of 9m N (2m lbf) aPplied in any direcl¡on at any point on thetop ra¡|.
9.Handra¡ls sháll be on both s¡des of strailh stairs; handrails shall also be on both sk es of circular s¡a¡rs wtlen theclearance between the tank shell and the sta¡r stringer exceeds 20o mm (8 in.).
10.Circumferemial stairways shall be complelely supported on the shell of the tank, and the ends of the stringers shall beclear of the ground. §a-iMays shall extend fiom the bouom of the tank up to a roof edge landing or gauger's PlaÚofm.
alt is recommended that the same angle be employed for all stairwa)s in a tank grouP or pla area.
5-76 API SraNoaRo 650
Table 5.1ga-Rise, Run, and Angle Relat¡onsh¡ps for Sta¡rways (St)
Height of R¡semmR
2.R+¡=610mm 2P+¡=660mmw¡drh of Run
mmf
Angle w¡drh of Runmm
f
Angle
Degrees Minutes Degrees Minutes
135 340 21 39
140 330 22 59 380 20 13
145 320 24 23 370 21 24
150 310 25 49 360 22 37
155 300 21 19 350 23 53
165 2AO 30 31 330 26 34
170 2'to 32 12 320 21 59
180 250 35 45 300 30 58'185 240 37 38 290 32 32
190 230 39 34 280 34 'r0
'195 220 41 33 270 35 50
205 200 45 42 250 39 21
210 190 41 52 240 41 1',1
2'15 230 A? 4
220 220 45 0
225 210 46 5B
Table 5.1gb-Rise, Run, and Angle Relationships for Staarways (USC)
He¡ght of R¡se¡n.x
2R + r= 24 in. 2R+ ¡=26in.W¡(lh of Run
¡n.f
Angle Width of Runin.Í
Angle
Degrees M¡nutes Degrees M¡nutes
5112 13112 21 39
51lz '13 22 59 15 20 'r3
53lq 12112 24 23 14112 21 24
6 12 25 49 14 22 31
6114 11112 21 19 13112 23 53
6112 1'l 30 3',1 13 26 34
63t1 1o112 32 12 12112 21 59
1 '10 45 12 30 58
1111 9112 37 38 11112 32 32
7112 I 39 34 11 34 10
1311 8112 41 33 1O112 35 50
B 8 45 42 10 39 21
8114 7112 47 52 9112 41 11
8112 I 43 4
83t 81h 45 0
9 I 46 58
WELoEo TANKS FoR OIT SToRAGE 5-71
qe/r6 in. Diameter hole
I
Notes:1. Lug materia, shall be austendrc sta¡nless
sleel when attached to carbon or low alloysteel parts. When attached to othermaterials, lug materia¡ shall be similar lo thematerial to whicñ attached.
2. See tank draw¡ng/daia sheel for elevationand orientátion.
3. Drawing courlesy of PIP (Proc6ss lndustryPracfces).
1/a ¡n. thickSee Note 'l Radius corners
lnsulat¡on(if required)
F¡gure s.23-crounding Lug
5.9 Top and lntermediate Stiffen¡ng R¡ngs
5.9.1 General
An open-top tank shall be prov¡ded with st¡ffening r¡ngs to maintain roundness when the tank ¡s subjected to windloads. The stiffen¡ng rings shall be located at or near the top of the top course, preferably on the outside of the ¡ankshell. This design for r¡ngs used as w¡nd g¡rders also appl¡es to float¡ng-roof tanks covered in Annex C. The top angleand the w¡nd girders shall conform, in rnaterial and size, to the requirements of this standard.
5.9.2 Types of Stiffening Rings
St¡ffening rings may be made of structural sections, formed plate sections, sections built up by weld¡ng, orcombinat¡ons of such types of sections assembled by welding. The outer periphery of stiffening r¡ngs may be ciréularor polygonal (see Figure 5.24).
5.9.3 Restrict¡ons on Stiffening R¡ngs
5.9'3'1- The- m¡nimum size of angle for use alone or as a component ¡n a hl¡lt-up süffen¡ng ring shall be 65 x 65 x 6mm(2112x2112x l/a in.). The min¡mum nom¡nalth¡ckness of páte for use in tormeO or nui[-úp siíffening rings shall be6 mm (0.236 in.).
5.9.3.2 When the stiffen¡ng rings are located more than 0.6 m (2 ft) below the top of the she , the tank shall beprovidedwitha65x6Sx6mm(2112x2112\.31l(.in.)¡opcurbangleforshellssmm(:hoin.¡rtrick,witnaT5xTSx6
// oo r'ror parrr i/
[Sl uñ¡ts omitted for clarityl
API STANDARO 650
mm (3 x 3 x 1/4 in.) angle for shells more than 5 mm (3ho in.) th¡ck, or w¡th other members of equivalent section
modulus.
. 5.9.3.3 Rings that may trap liqu¡d shall be prov¡ded with adequate drain holes. Un¡nsulated tanks having rings shall
have small water-shedding slopes and/or drain holes or slots unless the Purchaser approves an alternate means of
dra¡nage. lf drain holes are provided, they shall be at least 25 mm (1 in.) diameter (or slot width) on 2400 mm (8 ft)
centeri or less. lnsulated tanks where the r¡ngs function as ¡nsulat¡on closures shall have no drain holes or slots.
5.9.3.4 Weldsjo¡ning stiffening r¡ngs to the tank shell may cross vertical tank seam welds. Any splice weld ¡n the ring
shall be located a m¡nimum of 150 mm (6 in.) from any venical shell weld. Stiffen¡ng rings may also cross vertical tank
seam welds with the use of coping (rat hole) of the st¡ffen¡ng r¡ng at the vertical tank seam. Where the cop¡ng method
is used, the required section modulus of the süflening ring and weld spacing must be ma¡ntained.
5.9.4 Stiffen¡rE R¡ngs as Walkways
A stiffening ring or any pon¡on of it that is specif¡ed as a walkway shall have a width not less than 710 mm (28 ¡n.)
ctear of pó¡ecti-ons including the angle on the top of the tank shell. The clearance around local pKiect¡ons shall not be
less tnan OiO mm (2¿ in.). Únless the ank is covered with a fixed rool the stiffen¡ng ring (used as a walkway) shall be
located 11OO mm (42 in.) below the top of the curb angle and shall be provided with a standard rail¡ng on the
unprotected s¡de and at the ends of the section used as a walkway.
5.9.5 Supports for Stiffen¡ng R¡ngs
Supports shall be prov¡ded for all stitren¡ng ings when the d¡mension of the horizontal leg or web exceeds 16 ümes
the ieg or web thiékness. The suppons sñall be spaced at the intervals required for the dead load and vertical live
load; ñowever, the spacing shall not exceed 24 t¡rnes the w¡dth of the outs¡de compression flange.
5.9.6 Top W¡nd Girder
5.9.6.1 The requ¡red min¡mum section modulus of the süffen¡ng ring shall be determ¡ned by the following equaüon:
ln Sl units:
,=#(i,)'where
Z is the requ¡red m¡nimum secl¡on modulus, in cm3;
D is the norninal tank diameter, ¡n meters;
H2 is the he¡ght of the tank shell, ¡n rneters, including any fteeboard provided above the maximum filling heigltt
as a guide for a floating roof;
y is the des(Jn wind speed (3-sec gust), in km/h (see 5.2.1[kD.
ln USC units:
5.78
z=o.wlüHz({z)'
WEToEo fANKS FoR O[ SToRAGE
where
Z is the requ¡red minimum section modulus, in inches3;
, ¡s üe nominal tank diameter, in feeu
¡12 is the height of the tank shell, in feet, ¡nclud¡ng any fieeboard provided above the maximum f¡lling height asa guide for a floating roof;
y is the design wind speed (3-sec gust), in mph (see 5.2.1[kl).
NOTE For tank diámeters over 60 m (2m fr), the seclion modulus requ¡red by the equat¡on may be reduced by agreementbetween the Purchaser and the Manufacturer, but the modulus may not be less lhan that required for a tank diameter of 61 m(2m fr). (A descr¡ption of the loads on the tank shellthat are included in the design wind speed can be found in ltem a of the nole to5.9.7.1.)
5.9.6.2 The section modulus of the süffening r¡ng shall be based on the properties of the applied members and may¡nclude a portion of the tank shell for a distance of 16¡below and, if applicable, above the shell-ring attachment where¡is the as-bu¡[t shell th¡ckness, unless otherwise specmed. When curb angles are attached to the top edge ofthe shellring by butt-weld¡ng, th¡s distance shall be reduced by the width of the vertical leg of the angle (see Figure 5.24 andTable 5.20a and Table 5.20b).
5.9.6.3 When a stair opening is ¡nstalled through a stiffening r¡ng. the section modulus of the portion of the ringouEide the opening, including the transition section, shall conform to the requirements of 5.9.6.1. The shell adjacentto the open¡ng shall be stiffened with an angle or a bar, üe wide side of wh¡ch ¡s placed ¡n a horizontal plane. Theother s¡des of the opening shall also be stiffened with an angle or a bar, the w¡de s¡de of wh¡ch is placed ¡n a venicalplane. The cross-sectional area of these rim süffeners shall be greater than or equal to the cross-sectional area of theportion of shell included in the section-modulus calculaüons for the stiffening ring. These rim stifieners or additionalmembers shall prov¡de a suitable toe board around the open¡ng.
The stiffening memb€rs shall extend beyond the end of the opening for a distance greater than or equal to them¡nimum depth of the regular r¡ng sections. The end süffening members shall frame ¡nto the s¡de süfien¡ngmembers, and the end and side stiffen¡ng members shall be connected to ensure that the¡r full strength iideveloped. Figure 5.25 shows the open¡ng descr¡bed ¡n this section. Altemat¡ve details that prov¡de a load-carryingcapacity equal to that of the girder cross-section away from the opening may be provided.
5.9.7 lntermed¡ate Wind G¡rders
5.9.7.1 The maximum he¡ght of the unstiffened shetl shall be calculated as follows:
ln Sl units:
Hl
a = r.nrrr6'(fl'
where
is the vert¡cal distance, in meters, between üe intermediate wind g¡rder and the top angle of the shell or rhetop wind girder of an open-top tank;
is the nominal th¡ckness, unless otherwise specif¡ed, of the th¡nnest shell course, ¡n m¡llimeters (see Note1);
is the nominal tank diameter, ¡n meters;
5-80 API STANDARD 650
Figure s.2/t-Typ¡cal st¡ffening-r¡ng sections for Tank shells (see Table 5.20a and Table 5.20b)
WETDEo TANKS FoR OtL SToRAGE 5-81
Table s.2oa-Section Modul¡ (cm3) of Stiffening-Ring Sections on Tank Shells (Sl)
Dimens¡ons in millimeters
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6
Member S¡ze5
As-Buih Shell Th¡ckn€
68rss
10 11
Top Angle: Figure 5.24, Deta¡l a
65x65x6 6.54 ti. /65x65x8 8.46 8.63
75 x 75 x l0 13.82 13.97
Curb Angle: Figure 5.24, Detail b
65x65x6 2t.O3 28.1665x65xB 33.05 t4.6775x75x6 35.98 37.4975x75x10 41 .24 53.84100x100x7 63.80 7 4.64100x100x'10 71 .09 87.69 i -
One Angle: Figure 5.24, Deta¡l c (See Note)
65x65x6 28.09 29.15 30.73 32.O4 32.6965x65x8 34.63 36.20 I 38.51 40.32 41.11100x75x7 60.59 63.21 r 66.88 69.48 70.591O2x75xB 66.97 70.08 i 74.49 17 .60 78.90125x75x8 89.41 93.71 99.86 104.08 105.78125x15x10 105.20 110.71 118.97 124.68 126.91150 x 75 x 10 134.'14 141.38 152.24 159.79 't62.78
150 x-loox 10 155.91 111.'t1 'r 84.11 193.08 196.62
Two Angles: F¡qure 5.2,1, Deta¡l d (Se€ Note)
lOOx7sxB 181.22 186.49 I 195.15 201.83 204.62lmx 75 x 10 216.81 223.37 234.55 243 41 241.16l25x75x8 249.17 256.84 269.59 279.39 283.45
125 x 75 x 10 298.77 308.17 324.40 337.32 342.77150x75x8 324.97 335.45 353.r2 366.82 312.48
15O x 75 x 10 390.24 402.92 425.14 443.06 450.61150 x 10Ox 10 461.11 413.51 495.62 513.69 521.41
Forrned Plate: F¡gure 5.24, Deta¡l e
b=25O 341 375 392 399D=«n 427 413 496 505D= 350 519 517 606 618á= 400 615 687 723 131b=450 117 802 846 864D=500 824 923 976 996ó=550 937 1049 '11t1 1135,=600 1054 1181 1252 1280D=650 1176 13 t7 1399 1432b=l$ I 1304 1459 1551 1589b=150 1436 1607 1709 17 52ó= 800 1573 i 1759 1873 1921á=850 I - 1716 I 1917 2043 2096D=9oo i - 1864 2080 2218 2216ó=950 2016 2248 2398 2463ó = 1000 2114 2421 25A4 2654
NOTE The sect¡on moduli for Deta¡ls c and d¿with uncvFn lcnq arÉ rl<prl
5-42 API STANDARD 650
Column I Column 2 Column 3 Column 4 Column 5 Column 6
Member S¡zeAs-Built shell Thickness
3ho llc 5/ro 3la 1le
Top Angle: Figure 5.24, Detail a
21l2x21lzx1la 0.41 o.42
21lz x 2112 x5116 0.51 o.52
3x3x3/B 0.89 0.91
Curb Angle: F¡gure 5.24, Deta¡l b
21lzx21lzx1lc 1.61 I .12
2112 \ 2112 x5116 'r.89 2.O4
3x3x1/r 2.32 2.44
3x3x3/g 2.14 3.35
4 x4 x114 3.64 4.41
4x4x3l} 4.11 5.82
One Angle: Figure 5.24, Detail c (See Nole)
2112x2112x1ll 1.68 t.79 1.87 1.93 2.OO
2rlzx21lz\5116 '1.98 2.-t3 2.23 2.40
4x3x1/l 3.50 3.73 3.89 4.00 4.10
4x3x5/16 4.'t 4 4.45 4.66 4.82 4.95
5x3x5/16 5.53 5.96 6.25 6.41 6.64
5x31/2x5/16 6.13 6.60 7.16
5x3l/2x3l8 1 .O2 7.61 8.03 8.33 8.58
6x4x3/8 9.02 10.56 11 .15 11.59 11.93
Two Ang¡es: F¡gure 5.24, Deta¡l d (See l{ote)
4x3x5/16 11.21 1.78 '12.20 12.53 12.81
4x3xr/8 13.06 13.67 14.18 14.60 14.95
5x3x5/16 15.48 16.23 16.84 11 .34 11 .7 4
5x3x3/B 18.00 '18.89 19.64 20.26 20.11
5x3l/2x5116 16.95 1't.10 18.31 'r 8.82 19.23
5x31/2x3l8 '19.75 20.63 21.39 22.O1 22.54
6x4x3/B 21.74 28.92 29.95 30.82 31.55
Formed Plate: F¡gure 5.24, Deta¡l e
ó= 10 23.29 24.63 25.61 26.34
b=12 29.21 31.07 32.36 33.33
b= 14 35.49 37,88 39.53 40.78
ó= 16 42.06 45.07 41 .10 48.67
b=18 48.97 s2.62 55.07 56.99
b=20 56.21 60.52 63.43 65.73
b=22 63.80 68.78 12.18 74.89
b=24
-ñ-ñ-ñ--En-
--6 44---T= 36
--l= 38
- --6:40
NOTE The sectbn nrcwih uneven legs are us(
11.12
79.9988589t52
106,.78
11639r263313650Ml 21d on the
17.39863595.6610531115301216/.13632147 3515&71
81.3090791oo6s110.88uA7132 A2:'!,tl3155,40167 A2
84.4594A110L1711r52126.6613817150'07f6Lu1749S
Table s.zob-Sect¡on Modul¡ (in.3) of St¡ffen¡ng-Ring Sections on Tank Shells (Usc)Dimensions in ¡nches
WEtDEo TANKS FoR OrL SToRAGE 5-83
--' --\-¡Y¿¿. Ii\\ \\\L-'---fi\ - --r I
\"' ttt\ _/-)
F¡gure 5.2s-Sta¡rway Open¡ng through Stiffen¡ng Ring
y is the design wind speed (3-sec guso, in km/h (see 5.2.1[kl).
USC units:
i/¡ = 600,000 ,W(H'where
14 ¡s the ven¡cal d¡stance, ¡n feet, between the intermediate wind g¡rder and the top angle of the shell or the topwind girder of an open-top tank;
f ¡s üe nominal üickness, unless otherwise specit¡ed, of the üinnest shell course, in inches (see Note t);
D is the nominal tank d¡ameter, ¡n feet;
y is the design w¡nd speed (3-sec gust), ¡n mph (see 5.2.1[kl).
NOTE 1 .. The.§ructrral stability check of wind girder stiffened shelh in accordánce with 5.9.6 and 5.9.7, shall be based uponnom¡nal dimens¡ons of the shell course and the wind g¡rders ¡respective of specif¡ed coros¡on allowances whenever the 'ilo'option is selected for "Check Buckl¡ng in Conoded Cond.z on the Data Sheet, Line g. Vühenevér the "yes" opt¡on is setected, thecheck musl be based upon the nominal d¡mensions minus the specifed conosion allowance.
API SIANDARD 650
NOTE 2 This fomula is intended to cover tanks with either open tops or closed tops and ¡s based on tlle following faclors (or the
UiáEounO fái Ure faclors given in this note, see ASCE 7 and'R. V Mccrath's '$ability of API gandard 650 Tank Shells): 21
a) The velocity pressure is:
p = 0.00256K2 Ka K¿ Vz I C = l 48 kPa (31 lbflft2)
where
I(z equals the velocity pressure exPosure coeñ¡c¡ent = 1 .04 for exPosure C at a he¡ght of 40 fl;
,(a ¡s 'l.O for all slruclures except those on isolated h¡lls or escarpments;
,(d ¡s the direcl¡onality factor = 0.95 for round tanks;
y equats 3-second gust design w¡nd speed = r9o kmih (120 mph) at 10 m (33 fr) above ground (see 5.2.1[kD;
I equals the ¡mportance factor = 1.0 for Category ll struclures;
G equals the gust faclor = 0.85 for exposure C
A 0.24 kpa (5 lbf/ftl intemal vacuum is added for inward drag on open-top tanks or for external Pressure on closed top tanks for a
toral of 1.72 kPa (36 lbfrt2).
b) The wind pfessure is uniform over the theoretical buckling mode of the tank sttell, which eliminates the need for a shape factor
for the wind load¡ng.
c) The modified U.S. Model Basin fomula for the critical unifom extemal Pressure on th¡n-wall tubes free from erd load¡ngs,
subjecl to the total pressure specified ¡n ltem a
d) When other factors are specmed by the Purchaser that are greater than lhe factors in ltems a, b, and c, the lotal load on the'
shell shall be modifreO accorOing!, ánd Hl shall be decreased by üe ratio of 1.72 kPa (36 lbít2) to th€ modiñed total Pressure.
5.9.7.2 After the maximum he¡ght of the unstiffened shell, FI\, has been determined, the he¡ght of the transfonned
shell shall be calculated as follows:
a) With the follow¡ng equat¡on, change the actual width of each shell course into a transposed w¡dth of each shell
course hav¡ng the top shell th¡ckness:
w,,=
whefe
Wi. is the transposed w¡dth of each shell course, in millimeters (¡nches);
W is the acual width of each shell course, in millimeters (¡nches);
t ¿¿- is the nominal thickness, unless otherwise specified, of the thinnest shell course, ¡n millimeters (¡nches);
,ád,Ú,risthenominalthickness,unlessotherwisesp€cified,oftheshellcourseforwhichthetfansposedwidthis be¡ng calculated, ¡n millirneters (¡nches).
b) Add the transposed widüs of the courses. The sum of the transposed w¡dths of the courses will give the height of
the transformed shell.
T*,"n)
21 R.V Mccrath, "Stab¡lity of API gandard 650 Tank Shells," PKEeedings of the Amer¡can'd.nrirg,
an eacan eeúobum lnstitute, New York, 1963, Vol 43'pP 458-469'Petroleum lnst¡tute, Sect¡on lll-
wELDED TANXs FoR OrL SToRAGE
v s.9.2.3 tf the he¡ght of the transformed shell ¡s greater than the maximum height ¡4, an intermediate wind girder is
requked.
5.9.7.3.1 For equal statility above and below the intermed¡ate wind g¡rder, the girder should be located at the m¡d-
he¡ght of the transforrned shell. The location of the girdef on the actual shell should be at the same course and sarne
relaiive pos¡tion as the locat¡on of the girder on the ransformed shell, using the thickness relat¡onship ¡n 5.9.7.2.
5.9.7.3.2 Other locations for the girder nny be used, provided the height of unsÜffened shell on the transformed
shell does not exceed Hl (see 5.9.7.5).
5.9.7.4 tf har the height of the transfomed shell exceeds the maximum he¡ght ¿Il, a second intermediate g¡rdef
shall be used to reduce the height of unsliffened shell to a he¡ght less than the max¡mlm.
S.9.7.S lntermed¡ate wind girders shall not be attached to the shell within 150 mm (6 ¡n.) of a horizontalioint of the
shell. When üe preliminary locaüon of a girder is with¡n 150 mm (6 ¡n.) of a horizontaljoint, the girder shall preferably
be located 150 mm (6 in.) -below
the joint; however, the maximJm unstiffened shell he¡ght shall not be exceeded.
5.9.7.6 The required m¡nimum secüon modulus of an ¡ntermed¡ate wind g¡rder shall be determ¡ned by the follow¡ng
equation:
ln Sl units:
- dH,( v\''= n \-so)
\- where
Z is the requ¡red minimum section modulus, in cm3;
D is the nominal tank diameter. in meters;
¡ú ¡s the venical distance, ¡n meters, between the intermediate wind g¡rder and the top angle of the shell or thetop wind girder of an open-top iank;
y is the design wind speed (3-sec Aust), in km/h (see 5.2.1[kl).
ln USC units:
,= du, ¡v¡'- 10.000 \ 120/
where
Z is the requ¡red minimum section modulus, in inches3;
D ¡s the nom¡nal tank diameter, in feet;
iIl ¡s the vertical distance, in feet, between the ¡ntermed¡ate wind g¡rder and the top angle of the shell or the topw¡nd girder of an open-top tank;
y is the des¡gn w¡nd speed (3-sec gusl), in mph (see 5.2.1[kl).
API STANoARo 650
NOTE A description of the loads on the tank shellthat are included an Ú|e des(ln únd speed can be found ¡n llem a of the noteto 5.9.7.1.
5.9.7.6.1 Where the use of a transformed shell pemits the ¡ntermediate wind girder to be located at a height that isless than fli calculated by the fomula ¡n 5.9.7.1, the spac¡ng to the m¡d-height of the transformed shell, Eansposed tothe he¡ght of the actual shell, may be subst¡ü.rted for Hl in the calculaüon for the minimum sect¡on modulus if the g¡rder
is attaclrcd at tfle úansposed locaüon.
5.9.7.6.2 The sect¡on modulus of the intermed¡ate wind gkder shall be based on the properties of the attachedmembers and may ¡nclude a portion of the tank shell for a distance above and below the attachment to the shell, inmm 0n.), of:
ln Sl un¡ts:
13.4 (¿)ro 5
where
D ¡s the nom¡nal tank d¡arneter, ¡n meters;
Í is the as-built shell th¡ckness, unless otherw¡se specified, at the attachment, in millimeters.
ln USC units:
r.47 (DOo 5
where
D ¡s the nominal tank d¡ameter, in feeU
¡ ¡s the as-buift shell thickness, unless otherwise specified, at the aüachment, in ¡nches.
. 5.9.7.7 An opening for a sta¡May ¡n an intermediate stiffener is unnecessary when the intermediate stiffener
extends no rnore than 150 mm (6 ¡n.) from the outs¡de of the shell and tfle nominal stairway widh is at least 710 mm(28 in.). For greater outward extensions of a stiffener, the stain ,ay shall be increased ¡n width to provide a m¡nimum
clearance of 450 mm ('18 in.) between the outs¡de of the stiffener and the handrail of the sta¡rway, subject to thePurchaser's approval. lf an open¡ng ¡s necessary, it may be designed in a manner s¡m¡lar to that specified ¡n 5.9.6.3
for a top wind g¡rder with the except¡on that only a 560 mm (22 in.) w¡dth through the stiffener need be provided.
5.10 Roofs
5.10.1 Def¡nit¡ons
The follow¡ng defnitions apply to roof designs but shall not be cons¡dered as limit¡ng the type of roof permitted by
5.10.2.8.
a) A supported cone roof is a roof formed to approximately the sulace of a r¡ght cone that ¡s supported principally
e¡ther by rafters on girders and columns or by rafters on trusses with or wilhout columns.
b) A self-support¡ng cone roof ¡s a roof fomed to approx¡mately the sulace of a r¡ght cone that is supporled only
at its periphery.
c) A self-supporting dome roof is a roof fonned to approx¡mately a spherical surface that is suPPorted only at itsperiphery.
VIELDEo TANK§ FoR OIL SIoRAGE
d) A self-§upport¡ng umbrella ¡oof ¡s a mod¡ñed dome roof formed so that any horizontal secd¡on ¡s a regularpolygon with as many s¡des as there are roof plates that is supported only at its periphery.
5.'10.2 General
5.10,2.1 Loads: All roofs and supporting structures shall be des¡gned for load combinations (a), (b), (c), (e), (0, and(e).
5,10,2.2 Rool Plate Th¡ckness: Roof plates shall have a nominal lh¡ckness of not less than 5 mm (3/i6 in.) or 7-gauge sheet. lncreased thickness may be required for supported cone roofs (see 5.10.4.4). Any requ¡red conosionallowance for the plates of self-support¡ng roofs shall be added to the calculated th¡ckness unless otheftv¡se spec¡fiedby the Purchaser. Any conosion allowance for the plates of supported roofs shall be added to the greater of thecalculated th¡ckness or the minimum th¡ckness or [5 mm (3¡6 in.) or 7€auge sheetl. For frangible roof tanks, where aconos¡on allowance is specified, the design must have frangible characlerist¡cs in the nominal (unconoded) cond¡t¡on.
5.10.2.3 Strucfural Member Atlachmenú.' Roof plates of supported cone roofs shall not be attached to thesupporting members unless otherwise approved by the Purcñaser. Continuously attaching the roofto cone supportingmembers may be beneficial when ¡nterior l¡n¡ng systems are requ¡red, however, the tank roof cannot be consideredfrangible (see 5.'l 0.2.6).
5.10.2.4 Structunl Member Thickness: All ¡ntemal and extemal structural members shall have a minimumnom¡nal th¡ckness (new) of4.3 mm (0.17 ¡n.), and a minimum conoded thickness of2.4 mm (0.094 ¡n.), respecl¡vely,¡n any component, except that the m¡n¡mum nom¡nal th¡ckness shall not be less than 6 mm (0.236 ¡n.) for columnswhich by des¡gn normally res¡st ax¡al compressive forces.
5.10.2.5 Top Albcrrmeat Roof plates shall be attached to the top angle of the tank w¡th a cont¡nuous fillet weld onthe top s¡de.
5.10.2.6 Fnngible Roof.' A roof is cons¡dered frang¡ble (see 5.8.5 for emergency venting requ¡rement) ¡f the roof-to,shelljo¡nt urill fa¡l prior to the shelFto-bottom joint ¡n the event of excessive ¡ntemal pressure. VV¡en a Purchaserspecifes a tank w¡th a frangible roof, the tank des¡gn shall comply with a, b, c, or d, of the following:
a) For tanks 15 m (50 fr) ¡n d¡ameter or greater, the tank shall meet all of the following.
1) The slope of the roof at the top angle attachment does not exceed 2:'12.
2) The roof support members shall not be attached to the roof plate.
3) The roof is attached to the top angle w¡th a s¡ngle continuous fillet weld on the top s¡de (only) that does notexceed 5 mm (3/16 ¡n.). No unders¡de weld¡ng of roof to top angle (¡nclud¡ng seal welding) is permitted.
4) The roof-to.top angle compression ring ¡s l¡m¡ted to deiails a through e in Figure F-2.
5) All members ¡n the reg¡on of the roof-to-shell jo¡nl, includ¡ng ¡nsulat¡on rings, are considered as contributing tothe roof-tcshelljo¡nt cross-sectional area (A) and this area is less than the lim¡t shown below:
, D,"^ -
-2rF,
¡ang
NOTE The terms for this equation are def¡ned ¡n Annex F.
The lop angle size requ¡red by 5.1.5.9.e may be reduced ¡n size if requ¡red to meet the cross seciional area limil
WELoED fANKS FoR OIL SfORAGE
O A self-support¡ng umbrella roof is a rnodified dome roof fomed so that any horizontal secüon ¡s a regularpolygon with as many s¡des as there are roof plates that is supported only at its periphery.
5.10.2 General
5.10.2.1 Loads. All roofs and supporting structures shall be des¡gned for load combinaüons (a), (b), (c), (e), (f), and(0.
5.10.2.2 R@f Ptate Th¡ckness: Roof plates shall have a nominal th¡ckness of not less than 5 mm (3h6 ¡n.) or 7-gauge sheet. lncreased th¡ckness may be required for supported cone roofs (see 5.10.4.4). Any required coros¡onallowance for the plates of self-supporting roofs shall be added to the calculated lh¡ckness unless otheffvise specmedby the Purchaser. Any conosion allowance for the plates of supported roofs shall be added to the greater of thecálculated thickness or the minimum thickness or [5 mm (3/16 ¡n.) or 7-gauge sheetl. For frangible roof tanks, where a
conos¡on allowance ¡s specmed, the des¡gn must have frangible characteristics in the nom¡nal (uncoroded) condifon.
5.10.2.3 Structural Me¡nber Afrachrnent: Roof plates of supported cone roofs shall not be attached to thesupporting members unless othen ¡se approved by the Purchaser. ContinuoJsly atach¡ng üle roof to cone suppoÍtingmembers may be benefic¡al when ¡nterior lin¡ng s)6terns are requ¡red, however, üe tank roof cannot be consideredfrangible (see 5.10.2.6).
5.10,2.1 Saudural Merrúer Íhickness.' All ¡ntemal and external súuctrral rnembers shall have a m¡nirrumnom¡nal thickness (new) of 4.3 mm (0.17 in.), and a minimum conoded th¡ckness of 2.4 mm (0.094 ¡n.), resPectively,
¡n any componen[ except that the m¡n¡mum nominal th¡ckness shall not be less than 6 mm (0.236 in.) for columnswhich by des¡gn normally res¡st ax¡al compressive forces.
5.10.2.5 Top Aruchn errr.. Rmf plates shall be afrached to the top angle of the tank with a cont¡nuous f¡llet weld on
the top s¡de.
5.10,2.6 Frangibte Roof.' A roof is considered frang¡ble (see 5.8.5 for emergency vent¡ng requ¡rement) if the roof-to-shef jo¡nt w¡ll fail prior to the shell-to-bonom jo¡nt in the event of excessive intemal pressure. When a Purchaserspecmes a tank with a frangible rool the tank des¡gn shall comply with a, b, c, or d, of the following:
a) For tanks 15 m (50 ft) in d¡ameter or greater, üe tank shall meet all of the follo rirE.
1) The slope of the roof at lhe top angle attachment does not exceed 2:12.
2) The roof support members shall not be attached to the roof plate.
3) The roof ¡s anached to the top angle with a single conünuous fillet weld on the top s¡de (only) that does notexceed 5 mm (3/16 in.). No underside weld¡ng of roof to top angle (including seal welding) ¡s permmed.
4) The roof-to-top angle compress¡on r¡ng ¡s l¡mited to deta¡ls a through e in F¡gure F-2.
5) All members in the reg¡on of the roof-to-shelljoint, ¡ncluding insulaüon rings, are cons¡dered as contributing tothe roof-to-shelljo¡nt cross-sectional area (A) and this area ¡s less than the l¡mit shown below:
. DL,o = l-n F, tang
NOTE The terms for this equation are defined in Annex F.
The top angle sLe requied by 5.1.5.9.e may be reduced ¡n size if requ¡red to meet the cross sectional area limit.
API STANDARo 650
b) For sef-anchored tanks with a diameter greater üan or equal to 9 m (30 ft) hrt less than 15 m (50 ft), the tankshall meet all of Üle folloÚng.
1) The r,ank he¡ght ¡s 9 m (30 ft) or greater.
2) The tank shall meet the requ¡rements of 5.'10.2.6.a.2-5.
3) The slope of the roof at üe top angle attachrnent does not exceed 3/4:12.
4) Aüachments (¡ncluding nozzles and manholes) to the tank shall be des¡gned to accommodate at least 100 mm(4 ¡n.) of vertlcal shell movement without rupture.
5) The bottom ¡s bntt-welded.
c) Altemately, for self-anchored tanks less than 15 m (50 ft) d¡ameter, the tank shall rieet all of üe following.
1) The tank shall meet the requirements of 5.10.2.6.a.1 through 5.
2) An elastic analysis22 shall be performed to confirm the shell to bottomjoint strength is at least 1.5 times the topjo¡nt strength wih the tank empty and 2.5 tiries the topjo¡nt strengü with the tank full.
3) Attachrnents (¡ncluding nozzles and manholes) to the tank shall be des¡gned to accommodate at least 100 mm(4 in.) of vertical shell movernent without rupture.
4) The bottom ¡s bun-welded.
d) For anchored tanks of any d¡ameter, the tank shall meet the requ¡rernents of 5.10.2.6.a and the anchorage andcounterwe¡ght shall be des¡gned for 3 ümes the failure pessure calculated by F.6 as specmed in 5.12.
. 5.10.2.7 Stifreners: For all types of roofs, the dates may be stiffened by sections welded to the plates. Refer to5.10.2.3 for requirements for supported cone r@fs.
. 5.10.2.8 Altemate Designs: These rules cannot cover all deta¡ls of tank roof des¡gn and construction. With üeapproval of the Purchaser, the roof need not comply with 5.10.4, 5.10.5, 5.10.6, and 5.10.7. The Manufaclurer shallprovide a roof designed and construcled to be as safe as otherwise provided for ¡n this standard. ln the roof design,panicular anention should be g¡ven to preventing fa¡lure through ¡nstab¡lity.
5.10.2.9 Late¡al Loads on Columns.' When the Purchaser specif¡es lateral loads that will be imposed on the roo[supporting columns, the columns must be proport¡oned to rneet the requirements for combined axial compress¡onand bending as specmed ¡n 5.10.3.
5.10.3 Allowable Stresses
o 5.10.3.1 General
Ttle allowable strengh of roof componen6 shall be determined ¡n accordance with the ANSUAISC 360 using
allowable strength design methodology (ASD).
22 A frang¡ble roof sat¡sfes the emergency venting requ¡rement for tanks exposed to fire ou§ile tl|e !ank. See API 2OOO. Frang¡bleroob áre not ¡ntended to provide ernergency venting for other circumstances such as a f¡re inside the tank. ú¡lity fa¡lures,chem¡cal reactions, or overf¡ll. See API Publ¡cation 937 and API Publ¡caüon 937-4.
WELDED ÍANKS FoR OrL SToRAGE 5,89
5.10.3.2 Max¡mumSlendemess Rat¡os
For columns, the value L I r, shall not exceed 180. For other compression members, the value ¿ / ¡ shall not
exceed 2OO. For all other members, except tie rods whose design is based on tensile force, the value ¿ / ¡shall not
exceed 300.
where
¿ is the unbraced length, in m¡llimeters (inches);
r. is the least radius of gyration of column, in millimeters (¡nches);
¡ is the governing radius of gyration, ¡n millimeters (inches).
5.10.4 Supported Cone Roofs
. 5.10.4.1 The slope of the roof shall be 1:'16 or greater if specified by the Purchaser..lf the rafters are set diectly on
chord g¡rders, producing slightly varying rafter sÉpes, the slope of the flattest rafter shall conform to the specified or
ordered roof slope,
5.10.4.2 Main supporting members, ¡ncluding those supponing the rafters, nny be rolled- or fabricated sect¡ons or
fusses. Although ihese rñembers may be in cónUct witn tne roof plates, the comPress¡on flange of a member or üetop chord of a
"t¡uss shall be considóed as receiv¡ng no lateral support from the roof plates and.shall be laterally
bráced, if necessary, by other acceptable meüods. Tie allowable stresses ¡n these members shall be govemed by
5.10.3.
5.10.4.3 Súuctural members serving as rafters may be rolled or fabricated seclions but in all cases shall conform to
üe rules of 5.10.2, 5.10.3, and 5.10.¡. Raftefs shall-be designed for the dead load of üe rafters and roof plates with
üá "orpr"rsion
flange of ttre rafter cons¡dered as receiviñg no lateral support from the.roof plates and shall be
raieraity braceO ir necássary (see s.t0.4.2). When cons¡dering addiüonal dead loads or live loads, the rafters in direct
contaci wirh the roof plaÉ applying the loading to the rafters may be considered as rec€iving adequate lateral
support from the friction ¡etween tñe roof phtds and the compression flanges of the rafters, with the following
exceptions:
a) trusses and open-webjoints used as rafters;
b) rafters wiü a nom¡nal depth greater than 375 mm (15 in.);
c) rafters with a slope greater than 1 :6.
. 5.10.4,4 Rafters shall be spaced to saüsfy:
b = t(1.5 Fy/ D' <2loo mm (8'l in.)
where
b
Fy
t
P
is the maximum allowable roof plate span, measured circumferentially from center-tccenter of rafters;
¡s the spec¡fied m¡n¡mum yield strength of roof plate;
¡s the coroded roof th¡ckness;
is the uniform pressure as determined from load combinat¡ons g¡ven in 5.2.2.
API STANDARD 650
5.10.4.5 Roof columns shall be made from either pipe or structural shapes as selected on the Data Sheet, Line 11.Pipe columns shalleither be sealed or have openings on both the top and bouom of the column.
5.10.4.6 Rafter clips for the outer row of rafters shall be welded to the tank shell.
5.10.4.7 Roof support columns shall be provided at the¡r bases with deta¡ls that provide for the following.
a) Load Distibttt¡on Column loads shall be disributed over a bear¡ng area based on the specified so¡l bear¡ngcápacity or foundaüon design. The pressure appl¡ed by the tank l¡quid height need not be considered when si¿ngcolumn bases to d¡str¡bute loads. lf an unstifiened horizontal plate is designed to d¡stribute the load, it shall have anominal th¡ckness of not less than 12 mm (1/z in.). Alternatively, the column load may be distributed by anassembly of structural beams. The plate or members shall be designed to d¡stribute the load without exceedingallowable stresses prescr¡bed ¡n 5.10.3.1.
b) Corrosion and Abrasion Protection At each column a wear plate úth a nominal th¡ckness of not less than 6mm (1/l in.) shall be welded to the tank bottom with a 6 mm (U4 in.) min¡mum fillet weld. A single adequatethickness plate may be des¡gned for the dual funct¡ons of load distribrfion and conos¡on/abrasion Fotecüon.
c) Veft¡cal hbvenA¡rt The des¡gn shall allow üe columns to move vertically relative to the tank bottom withoutrestraint ¡n tf|e event of tank overpressure or bottom settlement.
d) Lateral Movemem. The columns shall be effectively gu¡ded at the¡r bases to prevent lateral rnovement. Thegu¡des shall remain effective ¡n the event of vertical rnovernent of columns relative to tank bonom of up to 75 mm(3 in.). The guides shall be located such that they are not welded directly to the tank bottom plates.
5.10.4.8 Three acceptable arrangements to prov¡de the funct¡ons required by 5.10.4.7 are ¡llustrated in F¡gure5.26.
5.10./t.9 For Annex F tanks, when supporting rnembers are attached to the roof plate, cons¡derat¡on shall be givento the design of the supporting rnemb€rs and their attachment details when cons¡dering internal pressure.
5.10.4.10 Center columns shall be des¡gned for both the balanced snow load and unbalanced snow load.lntermed¡ate columns need only be des¡gned for the balanced snow load.
5,10.5 Self-Supporting Cone Roofs
NOTE Self-support¡ng roofs whose roof plates are stiffened by sections lvelded to lhe plates need not conform to the min¡mumüickness requirements, br¡t the nominal th¡ckness of the roof plates shall not be less lhan 4.8 mm (3/16 ¡n.) when so des¡gned bythe Manufacturet subjecl to the approval of the Purchaser.
5.10.5.1 Sef-support¡ng cone roofs shall conform to the follow¡ng requirements:
o < 37 degrees (slope = 9 12¡
0 > 9.5 degrees (slope = 2:12)
ln Sl unib:
Nom¡nal thickness shall not be less than the greatest of **aU^E - ao, Ok ffi+ CA, añ 5 mm
Conoded thickness shall not be more than 13 mm.
WELoED TANKS FOR O[ STOMGE 5-91
Plate acl¡ng as Seal€d WearPlate that is also thick enoughto d¡stribute load
Plate that is thick enoughto d¡stribute load
F¡gure 5.26-Some AccePtable Column Base Deta¡ls
5-92 API STAÑDARD 650
where
, is the nominal d¡ameter of the tank, ¡n meters;
f ¡s üe greater of load comb¡naüons 5.2.2 (eX1) and (e)(2) with balanced snow load S¿, in kPa;
U is the greater of load comb¡nations 5 .2.2 (et(1) and (eX2) with unbalanced snow load S¡¡ ¡n kPa;
0 ¡s the angle of cone elemenE to the hor¡zontal, in degrees;
C,4 is the conosion allowance.
ln USC units:
Nominal thickness shall not be less than the greatest of #-^E.aO.rrft¡ffi*Ce.anO %o in.
Conoded th¡ckness shall not be rnore than 1/2 in.
where
, ¡s the nom¡nal diameter of the tank shell, in feet;
I is the greater of load combinat¡ons 5.2.2 (eX1) and (eX2) with balanced snow load S¡ (lbf/ft2);
U is the greater of load combinat¡ons 5.2.2 (e)(1) and (eX2) with unbalanced snow load So (|bflft2);
0 ¡s the angle of cone elements to the horizontal, ¡n degrees;
C,4 is the cofiosion allowance.
5.10.5.2 The partic¡Pat¡ng area at the roof-to-shell jdnt shall be determined us¡ng Figure F.2 and the nom¡nalmaterialthickness less any conosion allourance shall equal or exceed the follorúing:
pú84 tano
where
p is the greata of load comb¡nat¡ons 5.2.2 (eX1) and (eX2);
D is the nominal d¡ameter of the tank shell;
0 ¡s the angle of cone elernents to the horizontal;
F, equals (0.6 4), the least allowable tensile stress for the materials in the roof-to-shelljoint;
& is the Least Yeld Strength of roof-to-shelljoint material at max¡mum des¡gn temperaürre.
5.10.6 Self-Support¡ng Dome and Umbrella Roofs
NOTE Sef-supporting roots t/vñose roof plates are stifiened by seclions welded to the plates need not confom to the min¡mumth¡ckness requ¡remerts, br¡t üe th¡ckness of the roof plates shall not be less than 4.8 mm (3^6 in.) when so des¡gned by üeManufac{trer, suqject to the approval of the Purchaser,
WELoED TAN(S FoR OIL SIORAGE
5.10.6.1 Sef-support¡ng dome and umbrella roofs shall confom to ttle follot¡ving fequirenrents:
M¡nimum radius = 0.8, (unless otherwise specif¡ed by the Purchaseo
Max¡mum rad¡us = 1.2D
ln Sl units:
Nom¡nal th¡ckness shall not be less than the grei¡test of *E- r" ,', E+ CA" anrl 5 mm
Coroded th¡ckness shall not be more than 13 mm.
where
D ¡s the nominal diameter of the tank shell. ¡n meters;
f ¡s the greater of load combinations 5 .2.2 (e)(1) and (eX2) with balanced snow load S¿ (kPa);
U ¡s the greater of load cornbinaüons 5'2.2 (eX1) and (exz) with unbalanced snal load §, (kPa);
r¡ is the roof radius, in meters.
ln USC units:
Nom¡nal thickness shall not be less than the greatest of
^fr-"";*,8+ CA, and }16 in'
Conoded th¡ckness shall not be more than 1/2 in.
where
D is the nom¡nal diarneter of the tank shell, in feet;
I is the greater of load comb¡nations 5.2.2 (eX1) and (eX2) with balanced sriow load S¡ (lbf/ft2);
U ¡s the greater of load comb¡naüons 5.2.2 (eX1) and (eX2) wi¡h unbalanced snow load S, (lbf/ft2);
rr ¡s the roof radius, ¡n feet.
5.10.6.2 The part¡cipaüng area at üte rooftGshell jo¡nt derem¡ned us¡ng Figure F.2 and the nominal material
thickness less any conosion allowance shall equal or exceed:
where
p ¡s the greater of load comtinaliofls 5.2.2 (eX1) and (eX2);
, D is the nominal diameter of the tank shell;
8 4 tan0
API STANoARo 650
¡s the roof angle to horizontal at the shell. ¡n degrees;
equals (0.6 &), the least allowable tensile sEess for the materials ¡n the roof-to-shelljoinu
is the Least Y¡eld Súenglh of roof-to-shelljo¡nt material at maximum des¡gn temperature.
5.10.7 TopAngle Attachmer¡t for Self-Supporting Roofs
lnformation and certain restr¡ct¡ons on types of top-angle jo¡nts are provided ¡n ltem c of 5.1.5.9. Deiails of welding areprovided ¡n 7.2.
5.1'l Wind Load on Tanks (Overturning Stabil¡9
5.11.1 W¡nd Pressure
Overtrming stab¡lity shall be calculated us¡ng üe w¡nd pressures given in 5.2.1(k).
5.11.2 Unanchored Tanks
Unanchored tanks shall meet the requ¡rements of 5.11.2.1 or 5.11.2.2. See Figure 5.27.
W¡nd upliñ load
t
0
Fa
Fy
Wind load on shell
H/2 for uniform Ipressure on shell / Moñ!ents about
shellto bottom JointDead load (DL)
I
Liquid hold dolwr weigtrt 1w"¡
Figure s.27-Ovenurning Check for Unanchored Tanks
5.11.2.1 Unanchored tanks shall saüsfy all of the following uplift criteria:
'll O.6M*+ Mp¡< Mp¡11.5 + Mp¡p
2) M,+ FfMp) < (M¡¡+ M¡llZ + MpyT
3) Mws + Fp (MPi) < MDL l1-5 + WLR
lntemal pressure ¡oad
5-94
WETDED TANKS FOR OIL STOR^GE
wnere
Fp is the pressure combinaüon factor, se 5.?.2;
Mp¡ is the moment about the shell-to-bottom jo¡nt from design ¡ntemal pressure;
Mw is the ovemrming moment about the shell-to-bottom jo¡nt from horizontal plus vert¡cal wind pressure;
Mu ¡s the moment about the shell-to-bottom jo¡nt from the nominal weight of lhe shell;
Mp ¡s the nromenl about the shell-to-bottom jdnt from liqu¡d weight
Mp¿¡ is üe nnment about the shell-to-bottom joint from üe nom¡nal we¡ght of the roof plate plus any aüached
stuctural;
M¡a6 is the overtlming moment about the shell-to-bottom jo¡nt from horizontal wind Pressure.
5.11.2.2 Unanchored tanks with supported cone roofs meeting the requirements of 5.10.4 shall saüsry the follow¡ng
criteria:
M*+ F, Mn) < Motll.S + Mpy¡
S.11.2.3 The l¡quid weight (w¿) is the we¡ght of a band of l¡qu¡d at the shell us¡ng a specific gravity of 0.7 and a he¡ght
of one-hatf the d;sign t¡qu¡d héight ¡¿ w¿ ahall be the lesser ú 140.8 HD ¡or Sl Units (0.90 HD for USC units) or the
following:
\- ln Sl units:
wL = |g\rFb,H (Ntm)
ln USC unts:
wL = 4.67tb,1 :,H (lútft)
where
Fa, is the minimum specif¡ed yield stress of the bottom plate under the shell, in MPa (lbf/in.2);
l{ ¡s the des¡gn l¡quid height, in meters (fr);
, is the tank d¡arneter, ¡n meters (ft);
ló ¡s the requ¡red conoded thickness of the bottom plate under the shell, ¡n mm (inches), that ¡s used to resist
wind ovenuming. The bottom plate shall have the following restrictions:
1) The conoded thickness, fó, used to calculate w¿ shall not exceed the f¡rst shell course conoded thickness less
any shell conos¡on allowance.
2) When the bottom plate under the shell ¡s thicker due to únd overtuming lhan the remainder of the tank bottom,
the m¡n¡mum project¡on of the supplied thicker annular ring ¡nside the tank wall, ¿, shall be the greater of450 mm (18 ¡n.) or 16 however, need not be more than 0.035D.
API SfANoARo 650
ln Sl units:
Lb = o.ozgt to{-r¡ n< o.oss D (in meters)
ln USC units
¿ó = 0.365 to^fF¿a<0.035 D (in feet)
5.11,3 Anchored Tanks
When the requ¡rements of 5.11.2 cannot be saüsfied, anchor the tank per the requirements of 5.12.
5.11.4 Sl¡d¡rEFr¡ct¡on
Unless otherw¡se requ¡red, tanks that may be subject to slid¡ng due to wind shall use a max¡mum allowable slidingfriction of 0.40 multipl¡ed by the force aga¡nst the tank bottom.
5.12 Tank Anchorage
5,12,1 When a tank ¡s required to be anchored per 5.11, Annex E, Annex F, or when a tank is anchored for any otherreason, tlle following m¡n¡mum requirements shall be met.
5.12,2 Anchorage shall be pro\r¡ded to res¡st each of the uplift load cases listed in Table 5.21a and Table 5.21b. Theload per anchor shall be:
t¡= UN
where
¿, is the load per anchor;
U ¡s the net upln load per Table 5.21a and Table 5.21b;
y'f is the number of anchors (a m¡n¡mum of 4 ¡s required);
5.12.3 The spac¡ng between anchors shall not exceed 3 m (10ft).
5.12.4 Allowable stresses for anchor bolts shall be in accordance with Table 5.21a and Table 5.21bfor each loadcase. The allowable stress shall apply to the net (root) area of the anchor bolt.
. 5,12,5 The Purchaser shall specify any conos¡on allowance that ¡s to be added to the anchor dimem¡ons. Unlessothen¡vise specified, conosion allowance for anchor bolts shall be appl¡ed to the nominal diameter. The m¡nimumanchor bolt diameter ¡s 1 ¡n. plus any specified conosion allowance.
. 5.12,6 Attachment of the anchor bolts to the shell shall be through stitrened chair-type assembl¡es or anchor rings of
¡ sufficient size and heighl. An acceptable procedure for anchor cha¡r design is g¡ven ¡n AlSl §eel Plate Engineering
¡ Data, Volume 2, Pan 5, 'Anchor Bolt Chairs.'When acceptable to the Purchaser, anchor sfaps may be used if theshell attjachment ¡s v¡a cha¡r-type assembl¡es or anchor rings of suff¡c¡ent s¡ze and height.
5.12.7 Other evaluations of anchor attachments to the shell rnay be made to ensure üat local¡zed stresses in thestlell w¡ll be adequatety handled. An acceptable evaluaüon technique is given in ASME Sect¡on Vlll Division 2, Annex .-.4, us¡ng the allowable stresses given ¡n this section for Sr?. The method of attachment shall take into cons¡deration the \effect of deflection and rotation of the shell.
WEtoEo TANKS FoR OtL SToMGE 5-97
Table 5.21a-Uplift Loads (Sl)
Uplift Load Case Net Uplifr Formula, U(N)Allowable AnchorBolt Stress (MPa)
Allowable ShellStress al AnchorAttachment (MPa)
Des¡gn Pressure l(P 0.08f, x Ú x7851- tuyshzx F, 4t F,
Test Pressure [(Pr 0.08rrxdx785] -l{ slsx Fr 5t6 FD,
Failure Pressurea l(1.5 x Pr- 0.08¡i xdx785l - ltl3 Fr F¡y
Wind Load ,fl¡¡ x IP x 785 + [4 x lulwulfl - Wz 0.8 x Fy 516 Fry
Seism¡c Load 14x M /q- wz0 -0.4Ai 0.8xry \e Fo
Des¡gn Pressureb + Wind l(FpP+ n¡a - 0-08$ x Ú x7851 + 14 Mwul D - Wt slsx Fy 516 Fry
Design Pressufeb + Se¡sm¡c t(rpP- 0.08r¡) x Ú x7851+ 14 M",l D - $ 0 - 0.4Av\ 0-8xry \a r,
Frangibility Pressurec [(3xP¡-0.0810 xdx785] - t/¡ Fr
wtlere
Av is the ven¡cal eanhquake acceleration coeñ¡cient, in % g;
D h the tank diameter, in melers;
Fp is the pressure combinat¡on factor:
Fq, is the minimum yield strength of the bonom shellcourse, in MPa;
Fr ¡s the m¡nimum y¡eld strength ofthe anchor boh or 250 MPa, wh¡chever ¡s less' in MPa;
¡, is the tank he¡gh, ¡n meters;
nlhx equals .EJvs x D x ¡Plz, in N-m;
M* is the se¡smic moment. in N'm (see Annex E)i
I p is the desiqn pressure, in kPa (see Annex F);
I O is the failure Pressure, in kPa (see Annex F);
I
I p, b the test pfessure, in kPa (see Annex F);
I
I n " is the wind upliñ pressure on roof, ¡n kPa;
II an. is lhe wind pressure on shell, in N/mz;
I
I ," is the roof plate th¡ckness (the conoded th¡ckness wien used with l4 and nominalth¡ckness when used with
I wr), ¡n millimeters;II W, is lhe dead load of shell minus any conos¡on allowance and any dead load other than roof plate act¡ng on the
I shell minus any conosion allowance, in N;
I *, is the dead toad of strcll minus any conosion allowance and any dead load includ¡ng roof plate acting ofl the
I shell m¡nus any corosbn allowarrce, ¡n N;
I *, is lhe dead load of the shell using nom¡nal th¡cknesses and any dead load other than roof Plate acling on the
I shell usinq nominallhicknesses, ¡n N.
| , arr,r" ,,"orr" "pfrfies
to tanks fall¡rE under F.1.3 onty. The fa¡lue press.re shall be calcuhted using rpr¡r¡alth¡ckriesses
I o *"r", ,o ,.r., ao,"eminq the pressure comb¡nation factor appl¡ed to the design Yessure.
l" r.ang¡U¡¡ty p.essue appt¡es only to ianks de§gned to 5.10.2.6 d. The fiarE¡bility pressue shall be cahulated us¡rg nomir¡al th¡cknesses.
I
I
I
I
I
I
API STANDARD 650
Table 5.21b-Uplift Loads (USC)
Upl¡ft Load Case Net Upl¡ft Formula, U (lbf)Allowable
Anchor BoltStress (lbflin.2)
Allowable ShellStress at AnchorAttachment (lbfl
in.2)
Des¡gn Pressure l(P-stlxÚ x4.081 - I{ sltzx F, 2h Fv
Test Pressure f(&- 8tl x Ú x 4.08] - ltlr Slsx Fy \e F,
Fa¡lure Pressurea f(1.5 >< Pr 8tA x tj x 4.081 - lY3 F..
Wind Load .ffypx,dx{.08+ [4 x WHID|- W2 0.8 x ¡'l 516 F¡y
Se¡smic Load 14 x M*lDi - l4z 0 - 0.4Ai 0.8x& tk F,,
Design Pressureb + wind l(FrP+ fue-8t)x Ú x4.Bl+14 Me¡slDi - W1 5lgx Fy sla F,
Des¡gn Pressureb + Se¡sm¡c Í(FpP - &tl xÚ x4.O8l+l4LtntD)-W0-O.LAi 0.8 x F}, sls F,
Frang¡b¡lity Pressurec f(3 x Pf - 8tA \ d x 4.081 - W3 F,, Fry
where
Av ¡s the venical earthguake acceleration coefficiern, ¡n % g;
, is the tank diameter, in feet;
Fp is the pressure comb¡nation fador;
FA, is the min¡mum yield strength of the bottom shellcourse, in psi;
Fy is the minimum yield strength of the anchor bolt or 36,000 ps¡, wh¡chever is less. h psi;
É/ is the tank heillht, ¡n feet;
¡+Íws equals 8^/s x Dx #/2, in fr-lbs;
Mr\, ¡s the s€¡smic momert, in ft-lbs (see Annex E);
P is the des¡¡n pressure, ¡n ¡nches of water column (see Annex F);
P¡ ¡s the failure pressure, in inches of water column (see Annex F);
P¿ is the test pressure, ¡n anches of water column (see Annex F);
4ñR is the w¡nd uplift pressure on roof, ¡n irEhes of waler column;
fus is the wind pressure on shell, in lbs/fr2;
¡á ¡s the roof phte lhickness (the conoded th¡ckness when used with l,yl and nominalthickness when used with ,l/r, iniriches;
W is the dead load of shell minus any conos¡on allowance and any dead load other than roof plate ac¡ing on the shellminus any conosion allowance, ¡n lbf;
W2 is the dead load of shell minus any conosion allo^¡arrce and any dead load includ¡ng roof plate ad¡ng on tlle shellm¡nus any cofros¡on allowance, in lbf;
W3 is the dead load of the shell using nominal thicknesses and any dead load other than roof plate ad¡ng on the shellusing nom¡nal thicknesses, ¡n lbl
¿ Failure pfesstre applies to tanks falling under F.1.3 only. The fai¡úe prese.re shall be calculated us¡ng nori¡¡nal thickriesses.
b Refer to 5.2.2 concem¡ng Úle pressure combinaüon factor appl¡ed to the des¡gn pressure.
c Frangibility presqre apd¡e¡s only to tanks des¡gned to 5.10.2.6 d. The hang¡tnlry Fes$-re shall be cahrlated using nominal tlüclnesses.
5-S8
I
I
I
I
wEtoEo TANKs FoR OrL SfoR GE
5.12.8 Allowable stresses for anchorage parts shall be ¡n accordance with 5.10.3. A33% increase of the allowable
stress may be used for wind or se¡sm¡c loading condit¡ons.
5.12.9 The max¡mum allowable local stress ¡n the shell at the anchor attachment shall be in accordance with Table
5.21a and Table 5.21b unless an alternate evaluation is made in accordance with 5.12.7.
S.12.lO When specified by the Purchaser, the anchors shall be des¡gned to allow for thermal exPansion of the tank
resulüng from a temperature greater than 93 "C (20O "F).
5.12.11 Any anchor bolts shall be un¡formly tightened to a snug frt, and any anchor straps shall be welded wh¡le the
tank is f¡lled w¡th test water but before any pressure is applied on top of the water. Measures such as peening the
threads or add¡ng locking nuts, shall be taken to prevent the nuts from backing off the threads.
S.1Z.,IZ Íhe embedment strength of the anchor in the foundat¡on shall be suff¡cient to develop the specified
min¡mum yield strength of the anchor. Hooked anchors or end plates may be used to resist pullout.
5.12.13 The foundation shall provide adequate countefbalanc¡ng weight to resist the design uplift loads in
accordance with the following.
5.12.13,1 The counterbalanc¡ng weight, such asa concrete ringt rall, shall be designed so that the res¡stance to net
uplift is ¡n accordance with Table 5.21a and Table 5.21b. When considering uplift due to a w¡nd or seism¡c moment, an
evaluaüon shall be made to ¡nsure overtuming stability of the foundaüon and to ¡nsure soil-bearing pressures are
within allowable stress levels as determ¡ned us¡ng the recommendations of Annex B.
5..12.13.2 When a footing is ¡ncluded ¡n the r¡ngwall des¡gn, üe effective weight of the soil above the footing may be
¡ncluded ¡n the counterbalancing weight.
6.1 General
6.1.1 Workmanship
, 6.t.t.l All work of fabricating API e.g. 650 tanks shall be done in accordance with th¡s standard and with üepermissible ahematives specified ¡n the Purchaser's ¡nqu¡ry or order. The workmanship and f¡n¡sh shall be f¡rst class
in every respect and subject to the closest inspection by the Manufacturerb inspector even ¡f the Purchaser has
waived any part of the insPection.
6.1.1.2 When material requires stra¡ghtening, the work shall be done by Fessing or another noninjurious method
prior to any layout or shapiñg. Heatin§ or hammering ¡s not perm¡ssible unless the material ¡s ma¡nta¡ned at forging
tempera¡ure during straightening.
6.1.1.3 Materials used to a¡d inüe fabr¡cation of tanks shall not have a detrimental efiect on the structural integrity
of üe tank. Lubr¡cants, crayons, adhesives, and anti-weld spaüer compounds shall not contain materials that will be
detrimental to the tank, e.!. sufur and chloride compounds for stainless steel materials. Attachments that w¡ll be
welded to the pressure bou;dary shall not have a z¡nc or cadmium coat¡ng in the weld area within 12 mm (0.5 ¡n.) of
the weld.
6.1.2 F¡nish of Plate Edges
The edges of plates may be sheared, mach¡ned, chipped, or machine gas cut. Shearing shall be lim¡ted to plates less
ür" "rfirálio
io mrí 1:7s ¡r., rhick used for butt-wetded joins andio plates less thán or equal to 16 mm (s/8 in.)
thick used for lap-welded jo¡nts.
. NOTE Wiih the purchaser's approval, the shearing l¡m ation on plates used for hfi-welded jo¡nts may be increased lo athickness less than or equalto 16 mm (5/8 in.).
When edges of plates are gas ütt, the resulting surfaces shall be uniform and srnooth and shall be freed from scale
and slag áccumulations beiore wetding. After cut or sheared edges are w¡re brushed, the fine f¡lm of rust adhering to
me eOgÉs need not be removed befoie weld¡ng. Circumferentiál edges of roof and bottom plates may be manually
gas cut.
. 6.1.3 Shap¡n{, of Shell Plates
Figure 6-1 prov¡des criter¡a for shaping of plates to the curvature of the tank prior to ¡nstallation in the.tank. Shaping of
pátes conéunenüy with inshllaüon in üe tank shell ¡s permmed if the tank diameter exceeds the limit in F¡gure 6.1 or
if the Mandacturer's altemate procedure for any diameter has been accepted by the Purchaser.
6.1.4 Mark¡ng
SECTION o_FABRICATION
All spec¡al plates that are cut to shape before shipment as well as roof-supporting structural members shall be
marked as shown on the Manufacturer's drawings.
6.1.5 Shipping
plates and iank material shall be loaded ¡n a rnanner that ensures del¡very without damage. Bolts, nuts, n¡pples, and
other small parts shall be boxed or put ¡n kegs or bags for sh¡pment. All flange faces and other machined surfaces
shall be protected against conosion and from phys¡cal damage.
6-'1
6-2 API SIANoARD 650
.J
t
o)
§ 16,9Fo§1rgo
U)
1206040 )
t
1tz
Tank D¡ameter
NOTE Any combinat¡on of d¡ameter and thickness falling on orabove the solid line requires shap¡ng prior to insiallat¡on.
F¡gure 6.1-Shaping of Plates
6.2 Shop lnspect¡on
6.2.1 The Purchaser's inspector shall be permitted free enry to all parts of the Manufacturer's plant that areconcerned with the contract whenever any work under the contract is being performed. The Manufacturer shall affordthe Purchasers ¡nspector all reasonable facil¡ties to assure the inspector that the material is being furnished inaccordance with this standard. Also, the Manufacturer shall fum¡sh samples or spec¡mens of mater¡als for thepurpose of qualify¡ng welders in accordance with 9.3.
Unless otherwise specif¡ed, ¡nspect¡on shall be made at the place of mandacture pr¡or to shipment. The Manufactrershall g¡ve the Purchaser ample notice of when the mill will roll the plates and when fabr¡cat¡on will begin so that thePurchaser's ¡nspector may be present when required. The usual mill test of plates shall be deemed sufficient to provethe quality of the steel furnished (except as noted ¡n 6.2.2). Mill test reports or certmcates of compl¡ance, as providedfor in the material specification, shall be furnished to the Purchaser onty when the opt¡on ¡s specmed in the originalcontract that they be prov¡ded.
6.2.2 M¡ll and shop inspect¡on shall not release the Manufacturer from respon§b¡lity for replac¡ng any defect¡vematerial and for repairing any defect¡ve workmansh¡p üat rnay be dlscovered ¡n the l¡eld.
6.2.3 Any mater¡al or workmanship that in any way fails to meet the requ¡rements of th¡s standard may be rejectedby the Purchaser's inspector, and üe material involved shall not be used under the contract. Material that stnws¡njurious defecb subsequent to its acceptance at üe mill, subsequent to its acceptance at the Manufacturerb works,or dur¡ng erection and inspect¡ng of the tank will be rejected. The Manúacturer will be noüfied of this ¡n wr¡t¡ng and w¡llbe requ¡red to fumish new material prompdy and make the necessary replacements or suitable repairs.
10
q8
3la
31rc
3618
Shaping requiredprior to installation
I
Shap¡ng not required
ll
WEtoEo TANKS FoR OlL SToRAGE
6.2.4.a fhe Manúacturer shall visually inspect all edges of shell and roof plates before installing the plates ¡n the
tank or before inserting a nozzle into the plate to determine if laminations are present. lf a lamination is visually
detected, the Manufacturer shall ultrason¡cally examine the area to determine the extent of the laminations and shall
rq¡ect the plate or make repa¡rs in accordance with 6.2 4b.
6.2.4.b For laminat¡ons found not exceeding 75 mm (3 in.) ¡n length or 25 mm (1 in.) in depth, repairs may be made
by edge gouging and rewelding to seal the Éminat¡on. The Mandacturer shall submit the edge repair procedure for
elrcnásó acieitance prior toihe start of fabricat¡on. For laminations exceeding these l¡mits, the Manufacturer shall
either reject thé plate'or repa¡r the plate by enfrely removing the lamination. Before making such repa¡rs the
Manufaciurer shail document the extent of thé lamination and submit a case-spec¡f¡c repair Procedure for Purchaser
approval.
SECTION 7_ERECT¡ON
7.1 General
7.f.1 Requ¡red foundation and grade work shall be supplied by the Purchaser, unless otherwise specified in the
Contract. ihe Manufacturer shai check level tolerances and contour before staning work, and shall notify the
purchaser of any deficiency discovered that might affect the qual§ of the finished wofk. Deficienc¡es noted shall be
rect¡f¡ed by the Purchaser unless otherwise agreed by the Mantfacturer'
7.1.2 After the purchaser has tumed the tank foundalon over to the Mantfacturer, üe Manufacturer shall ma¡niain
the grade under the tank ¡n true profile and free of fore¡gn materials such as clay, coal, c¡nders, metal scraps, or
ánim'ai o, ueg"taOte maner of any soñ. The Manufactureishall repair any damage to either the foundaüon or grade
sulace caused by the Manufacturer s operaüons.
7.1.3 Coaüng or foreign mater¡al shall not be used between surfaces ¡n contact in the construct¡on of the tank,
except as permitted by 7 .2.'1.1o.
7.1.4 Coat¡ng or othef protect¡on for structural work ¡nside and outside of the tank shall be as specmed ¡n üecontraci and shall be apPlied by competent workers'
7.1.5 All temporary attachme s welded to the exterior of the tank shall be removed and any not¡ceable projections
ot weld metalitrall-be ground smooth with the suface of the plate. ln the event of ¡nadvertent tear¡ng of the plate
when atrachments are iemoved, the damaged area shall be iepaired by welding and subsequent grind¡ng of the
surface to a smooth cond¡t¡on.
7.1.6 All temporary attachments welded to the interior of the tank, ¡ncluding the shell, roof, tank bottom' roof
columns and other internal stsuctufes shall be removed and any not¡ceable projections of weld metal shall be groxnd
smooth. ln the event of inadvenent tearing of the plate when áttachments are removed, the damaged area shall be
r"puir"O Uy welding and subsequent grináing of üe surface to a smooth condit¡on. This work must be completed
uefore tre apptfariion of intemai lin¡nó, rhe;ir ra¡sing of a fixed rool the ¡nitial float¡ng of a floating roof, and any
other circumstance whereby projecüons may cause damage.
7.2 Details of Weld¡ng
7.2.1 General
7.2.1.1 Tanks and the¡r süuctufal a[achments shall be welded by lhe sh¡elded metal-arc, gas metal-arc, gas
irngi "n-ura,
oxyfuel, flux-cored arc, submerged-arc, electroslag, or electrogas. process using suitáble equ¡pment'
uid ot tt" oxyfúet, electroslag, or electrogai process shall be by agreement between the Manufacturer and the
purchaser. Usá of ttre oryfuel irocess is noipermitted when impact testing of the material is required. All tank weld¡ng
snátt Oe pertormeO by- manual, semiautomat¡c arc, machine, or automat¡c weld¡ng ¡n accor_dance with lhe
,"qr¡r"r"k of Sect¡oá 9 of this standard and welding procedure specificaüons as descr¡bed in Section lX of the
nSh¡E Co¿e. welO¡ng shall be performed in a manner that ensures complete fusion with the base metal.
7.2.1.2 At the Purchaser's request, the Purchaser may designate aPplicable sections of API 582 for supplementary
welding guidelines and practices.
7.2.1.3 No welding of any kind shall be performed when the sufaces to be welded are wet from rain, snow or ice;
when rain or sno*-6 fallirig on such surfáces; or during periods of high winds unless the welder and the work are
properly shielded. elso, pre-heat shall be applied when metal temperature is below the temperature required by Table
i.lá añO faOle 7.1b. ln that case the base metal shall be heated to at least the temperature ind¡cated ¡n Table 7.1a
and Table 7.1b within 75 mm (3 in.) of the place where welding ¡s to be started and ma¡ntained 75 mm (3 in ) ahead of
the arc.
1.1
1-2 API STANoARD 650
Table 7.1a-(Sl) Minimum Preheat Temperatures
Material Groupper Table 4-4a
Thickness (t) ofTh¡cker Plate (mm)
Minimum PreheatTemperature
Groups l, ll, lll& tA
t<32 0"c
32< t<40 10 .c
f > 40 93 'C
Groups lV lVA,V&VI
t<32 10.c
32<t<40 40 "c¡> 40 93 "C
Table 7.1b-(USC) M¡n¡mum Preheat Temperatures
Material Groupper Table 4-4b
Th¡ckness (/) ofTh¡cker Plate (in.)
M¡n¡mum PreheatTemperature
Groups l, ll, lll& ItA
t<1.25 32 "F
1.25 < 1< 1.50 50 "F
1.50 200 .F
Groups lV lVA,V&VI
t < 1 .25 50 .F
1.25 < 1< 1.50 100 "F
,> 1.50 2m "F
7.2.1.1 Each layer of weld metal or mult¡layer welding shall be cleaned of slag and other deposits before the nextlayer ¡s appl¡ed.
7.2.1.5 The edges of all welds shall merge smoothly with the surface of the plate w¡thorit a sharp angle.
7.2.1.6 All welding shall be free from coarse ripples, grooves, overlaps, abrupt r¡dges, and valle)6 that interfere with¡nterpretat¡on of NDE results.
7.2.1.7 During the weld¡ng operation, plates shall be held ¡n close contact at all lapjclints.
.7.2.1.8 The method proposed by the Manufacturer for holding the plates in position for welding shall be submined tothe Purchaser's inspector for approval if approval has not aheady been g¡ven ¡n writ¡ng by the Purchaser.
7.2.f .9 Tack welds used during the assembly of verticaljo¡nts of tank shells shall be removed and shall not rema¡n inthe f¡n¡shedjo¡n6 when thejoinb are welded manually. When suchjo¡ns are welded by the submerged-arc process,the lack welds shall be thoroughly cleaned of all welding slag but need not be removed if they are sound and arethoroughly fused into the subsequently applied weld beads.
Whether tack welds are removed or left ¡n place, they shall be made using a f¡llet-weld or butt-weld procedurequalif¡ed in accordarice with Section lX of the ASME Code. Tack welds to be left in place shall be made by weldersqualmed in accordance wiü Section lX of the ASME Code and shall be visually exam¡ned for defecls, wh¡ch shall beremoved if found (see 8.5 for criteria for visual examinat¡on).
7.2.1.10 lf protective coat¡ngs are to be used on surfaces to be welded, the coaüngs shall be ¡ncluded in welding-procedure qualmcation tests for the brand formulation and max¡mum thickness of coating to be applied.
WELoED TaNKs FoR OrL SToRAGE 7-3
7.2.1.11 Low-hydrogen electrodes shall be used for all manual metal-arc welds ¡n annular rings and shell courses,
¡ncluding the attachment of the frst shell course to bottom or annular plates, as follows.
a) Where the plates are th¡cker than 12.5 mm (r/2 ¡n.) (based on the th¡ckness of the thicker member being io¡ned)and made of mater¡al from Groups l-lll.
b) For all thicknesses when the pates are made of material ftom Groups lV, IVA' V and Vl.
7.2,1.'l2 Non-structural small attachments such as ¡nsulation cl¡ps, studs and pins but not insulation support rings or
bars may be welded by the arc stud, capacitor d¡scharge or shielded rnetal arc process to the exterior of the shell
irrcluding reinforcing plátes or PWHT assembl¡es and roof either before or aftef hydrostatic tesiing ¡s performed, hjtbefore the tank will be f¡lled with product prov¡ded:
a) The attachment locafons meet the spac¡ng requirements of 5.8.1.2a.
b) The arc stud weld¡ng process ¡s l¡mited to 'lO mm (3/0 in.) max¡mum d¡arneter studs or equ¡valent cross-secl¡on.
c) The maximum shielded rnetal arc electrode is limited to 3 mm (1/8 ¡n.) diarneter and shall be a low-hydrogen type.
d) The atrachment welds, except for those made by the capacitor discharge method, shall be insPected per 7.2.3.6.
The attachment welds rnade by the capacitor discharge method shall be visually examined for all tyPes and
groups of shell materials.
e) All stud welding and capac¡tor discharge procedures have been qual¡f¡ed in accordance with ASME Section lX.
Capacitor dischlrge procedures do not requ¡re procedure qualif¡cation prov¡ded the power output ¡s 125 watt-sec
or less.
The sh¡elded metal arc weld procedures shall meet the requirernents of Section 9 for qualificaüon for use.
7.2.2 Bottoms
7.2.2.1 After the bottom plates are laid or¡t and tacked, they shall be jo¡ned by welding the joints ¡n a sequence that
the Manufacturer has found to result in the least distort¡on from shrinkage and thus to provide as nearly as poss¡ble a
plane surface.
7,2.2.2 fhe weld¡ng of the shellto the bottom shall be practically completed before the welding of bottomjoints that
may have been left open to compensate for shrinkage of any welds previolsly made is completed.
7.2.2.3 Shell plates may be aligned by metal clips attached to the bottom plates, and the shell may be tack welded
to the bottom before conünuous welding is started between the bottom edge of the shell plate and the bottom plates.
7.2.3 Shells
7.2.3.1 plates to bejoined by butr welding shall be matched accurately and reta¡ned in pos¡tion during the weldingoperaüon. Misalignment ¡n completed ven¡cáljoints for plates greater than 16 mm (5/8 in.) thick shall not exce€d'lo o/o
oi th" ptut" tt ickñ"ss or 3 mm (t/a in.¡, whichére, is less; misalignment for plates less than or equalto 16 mm (s/e in.)
thick shall not exceed 1.5 mm (1/16 in.).
7.2.3.2 tn completed horizontal butt jo¡nts, the upper pate shall not project beyond the face of th_e lower plate at anypoint by more than 20 9/o of üe th¡ckness of the upper plate, with a max¡mum projection of 3 mm_(r/s ¡n.); however, for
upper flates less than 8 mm (s/to in.) th¡ck, the naximum projecüon shall be limited to 1.5 mm (1/lo in.).
7.2.3.3 The upper plate at a hor¡zontal buttjoint shall have a 4:1 taper when its th¡ckness is more than 3 mm (1/8 in.)
greater than the lower plate.
1-4 API STANoARo 650
7.2.3.1 lhe reverse side of double-welded butt jo¡nts shall be thoroughly cleaned in a manner that will leave theexposed $Jrface saüsfaclory for fusion of the weld metal to be added, prior to the appl¡c¿t¡on of the f¡rst bead to thesecond side. Th¡s cleaning may be done by ch¡pping; grinding; rnehing oLrt; or where the back of the initial bead ¡ssmooth and faee from crevices that might entrap slag, another method that, upon field ¡nspection, is acceptable to thePurchaser.
7.2.3.5 For c¡rcumferential and verticaljo¡nts in tank shell courses consfuded of m¿rterial more than 40 mm (11/2
in.) th¡ck (based on the th¡ckness of the thicker plate at the joint), rrult¡pass weld procedures are requ¡red, with nopass over 19 mm (3/4 in.) thick permitted.
7.2.3.6 The requirements of th¡s sect¡on shall be followed when weld¡ng to Group lV, lVA, V, and Vl materials.Permanent and temporary attachrnents (see 7.2.1.11 for ¡nformation on shell-tGbottom welds) shall be welded withlow-hydrogen electrodes. Both permanent and temporary attachmenE shall be welded in accordance with aprocedure that min¡mizes the potential for underbead crack¡ng. The welds of permanent attachmens (not includingshell-to-bottom welds) and areas where temporary auachrnents are removed, shall be examined v¡sually and byeither the rnagnetic particle method or by the liquid penetrant method (see 8.2,8.4, or 8.5 for the appropriateexam¡naüon criteria).
7.2.3.7 Completed welds of stress-relieved assemblies shall be examined by visual, as well as by magnetic part¡cleor penetrant rnethods, after stress relief, but before hydrostatic test.
7.2.3.8 Flush-type connections shall be ¡nspected according to 5.7.8.11.
7.2.4 Shell-to-BottomWelds
7.2./t.1 The initial weld pass inside the shell shall have all slag and non-rietals rernoved from the surface of the weldand then examined for its ent¡re circumlerence both visually and by one of the follow¡ng methods to be agreed to byPurchaser and the Manufacturer. lf method "a" ¡s applied, either inside or outside weld may be deposited f¡rst. lfmethod b, c, d, or e ¡s applied, the inside weld shall be deposited f¡rst:
a) magnaic panicle;
b) applying a solvent l¡qu¡d penetrant to the weld and then apply¡ng a developer to the gap between the shell and thebottom and examining for leaks after a min¡mum dwell üme of one hour;
c) applying a water-soluble l¡qu¡d peneúant to either s¡de of the joint and then applying a developer to the other s¡deof the jo¡nt and examining for leaks after a m¡n¡mum dwell t¡me of one hour;
d) applying a h¡gh flash-point penetraüng oil such as light diesel to the gap between the shell and the bottom, lettingstand tor at least four hours, and examin¡ng üe weld fof ev¡dence of w¡cking.
NOTE Residual oil may rema¡n on the surfaces yet to be welded even aner the cleaning required below and comam¡nat¡on ofthe subsequent weld is possible.
e) Apptying a bubblejorm¡ng solution to the weld, using a right angle vacuum box, and examining for bubbles.
Thoroughly clean all residual exam¡nat¡on mateials from the as yet to be welded sufaces and from the unwelded gapbetween the shell and bottom. Remove defective weld segments and reweld as required. Reexamine the repairedwelds and a minimum of 150 mm (6 in.) to either side in the manner descr¡bed above. Repeat th¡s clean-remove-repair-examine-and-clean process unülthere ¡s no eüdence of leakirE. Complete allweld¡ng passes of thejo¡nt bothins¡de and outside the shell. Visually exam¡ne the f¡nished weld surfaces of thejoint both ins¡de and orts¡de the shellfor their enüre c¡rcumference.
WELDED faNKS FoR OtL SroRAcE 7-5
7.2.4.2 As an altemative to 1.2.4.1,lhe ¡nitial weld passes, inside and outside of the stlell, shall have all slag and
non-metals removed from the surface of the welds and the welds shall be examined v¡sually. Additionally, after thecompleüon of the inside and outs¡de fillet or partial penetfation welds, the welds may be tested by Pressur¡zing thevolume beNveen the ins¡de and ouEide welds with a¡r pressure to 1OO kPa (15 lbf/in.2 gauge) and apply¡ng a solut¡on
f¡lm to both welds. To assure that the air pressure reaches all parts of the welds, a sealed blockage in the annular
passage between the ¡nside and outs¡de welds must be prov¡ded by welding at one or more po¡nE. Additionally, a
small Ppe coupl¡ng commun¡cat¡ng with the volume between the welds must be connected at one end and a pressure
gauge connected to a coupl¡ng on the other end of the segment under test.
7.2.4.3 By agreernent between the Purchaser and the Mandacturer, the examinat¡ons of 7 .2-4.'l may be waived ifthe following examinat¡ons are peformed on the entire c¡rcumference of the weld(s).
a) Visually examine the in¡tial weld pass (¡nside or outside).
b) Visually examine the fin¡shed joint welded surfaces, both inside and outside the shell.
c) Examine either s¡de of the f¡nished joint weld surfaces by magnet¡c part¡cle, or liqu¡d penetrant, or right angle
vacuum box.
7.2.5 Roofs
Except for the stiFllat¡on that the structural fram¡ng (such as the rafters and girders) of the roof must be reasonably
true to l¡ne and surface, th¡s standard does not ¡nclude spec¡al stipulat¡ons for erection of the roof.
7.3 Examination, lnspection, and Repairs
7.3.1 General
7.3.1.1 The Purchaser's ¡nspector shall at all times have fiee entry to all parts of the job wh¡le work under the
contract is being performed. The MandactJrer shall afford the Purchaser's ¡nspector reasonable fac¡lities to assure
the ¡nspector üat the work is being performed ¡n accordance with this standard.
7.3.1.2 Any material or workmanship shall be subject to the replacement requirements of 6.2 3.
7.3.i.3 Mater¡al that is damaged by defedive workmanship or that ¡s otherwise defective will be rejected. The
Manufacturer will be notif¡ed of this in wriüng and will be required to fumish new material promptly or to conect
defect¡ve workmansh¡p.
2.3.1.4 Before acceptance, all work shall be completed to the saüsfaction of the Purchaser's inspecto¡ and the
enüre tank, when filled w¡th oil, shall be t¡ght and free from leaks.
7.3.2 Exam¡nation of Welds
7.3.2.1 Butt-Welds
Complete penetration and compleie fus¡on are required for welds jo¡n¡ng shell plates to shell plates. Exam¡nation for
the quality of the welds shall be made using e¡ther the rad¡ograph¡c mehod specified in 8.1 or altematively, by
agreement between the Purchaser and the Manufacturer, using the ultfasonic method specified ¡n 8.3.1 (see AnnexUr. ln addiüon to the rad¡ographic or ultrason¡c examination, these welds shall also be v¡sually examined.
Furthermore, the Purchaser's inspector rnay visually examine all butt-welds for cracks, arc str¡kes, excessiveundercut, surface porosity, incomplete fus¡on, and other defects. Accepiance and repa¡r criteria for the visual method
are specmed ¡n 8.5.
7-6 API STANoARD 650
7.3.2.2 Fillet Welds
Fillet welds shall be examined by the v¡sual method. The f¡nal weld shall be cleaned of slag and other deposits pr¡or toexamination. Visual examination acceptance and repair cr¡ter¡a are specified in 8.5.
7.3.2.3 Respons¡b¡lity
The Manufacturer shall be responsible for making radiographs and any necessary repa¡rs; however, if thePurchaser's ¡nspeclor requires radiographs ¡n excess of the number specif¡ed in Sect¡on 6, or requ¡res ch¡p-outs off¡llet welds ¡n excess of one per 30 m (100 ft) of weld and no defect is d¡sclosed the additional examinations andassociated work shall be the responsibility of the Purchaser
7.3.3 Examination and Testing of the Tank Bottom
Upon completion of weld¡ng of the tank bonom, the bottom welds and plates shall be exam¡ned visually for anypotential defec§ and leaks. Part¡cular attenüon shall apply to areas such as sumps, dents, gouges, three-plate lapls,bonom plate breakdowns, arc strikes, temporary attachment rernoval areas, and weld¡ng lead arc burns- Msualexamination acceptance and repa¡r criter¡a are spec¡fied ¡n 8.5. ln addition, all welds shall be tested by one of thefollowing methods.
a) A va@um-box test in accordance with 8.6.
b) A tracer gas test in accordance with 8.6.1 1.
c) After at least the lowest shell course has been atiached to the bottom, water (to be suppl¡ed by the Purchaser)shall be pumped undemeath the bottom. A head of 150 mm (6 ¡n.) of liqu¡d shall be ma¡ntained using a temporarydam to hold that depth around the edge of the bottom. The line contain¡ng water for test¡ng may be installedtemporarily by running it through a manhole to one or more temporary flange connect¡ons ¡n the bottom of thetank, or the line may be installed permanently in the subgrade beneath the tank. The rnethod of installat¡on shouldbe governed by the nature of the subgrade. Reasonable care shall be taken to preserve the prepared subgradeunder the tank.
7.3.4 lnspect¡on of Reinforcing-Plate Welds
After fabr¡cation is completed but before the tank is filled with test water, the reinforcing plates shall be tested by theManufacturer by applying up to 10O kPa (15 lbí¡n.z) gauge pneumat¡c pressure between the tank shell and there¡nforcement plate on each opening using the telltale hole spec¡fied ¡n 5.7.5.'1. While each space is subjected to suchpressure, a soap f¡lm, linseed o¡1, or another material suitable for the detection of leaks shall be applied to allattachment welding around üe reinforcement, both ¡nside and outside the tank.
7.3.5 Test¡ng of the Shell
After üe entire tank and roof structure ¡s completed, the shell (except for üe shell of tanks designed in accordancewiü Annex F) shall be tested by one of the following rnethods, as specil¡ed on the Data Sheet, Lin€ 14.
1) lf water ¡s ava¡lable for testing the shell, the tank shall be f¡lled with water as follows: (1) to the maximum designliqu¡d level, II, (2) to¡ a tank with a tight rool to 50 mm (2 in.) above the weld connect¡ng the roof plate orcompression bar to the top angle or shell; (3) to a level lower than that specmed in Sub¡tem 1 or 2 whenrestricted by overflows, an ¡nternal float¡ng rool or other freeboard by agreement between ttle Purchaser andthe Manufacturer, or 4) to a level of seawater produc¡rE a bottom of shell hoop stress equal to that produced bya fullhe¡ght fresh water test. The tank shall be inspected frequently during the fill¡ng operation, and any weldedjo¡nts above the test-water level shall be exam¡ned ¡n accordance with ltem 2 below. Th¡s test shall beconducted before permanent external pip¡ng is connected to the tank. Attachments to the shell defined ¡n
5.8.1.1, located at least 1 m (3 ft) above the water level, and roof appurtenances may be welded during thefilling of the tank. After completion of the hydro-test, only non-structural smal¡ attachments may be welded to theta nk ¡n accorda nce with 7 .2. 1 .1 1 .
I
a
WELDEo TANKS FoR OtL SToRAGE 1-1
2) lf sufficient water to fill the tank is not available, the tank rnay be tested by (1) painting all of the joints on the
¡nside with a h¡ghly peneúating oil, such as autornobile sping oil, and carefully examin¡ng the outside of tllejoins for leakagé; iZ) applying vacuum to either s¡de of the jo¡nts or apPly¡ng ¡ntemal air Pressure as sPecmed
ior the roof tÑ in 7.3.7 ánd-carefully examining the joints for leakage; or (3) using any comb¡nation of the
meüods st¡pulated in 7.3.5, Subitems 1 and 2.
7.3.6 HydrostaticTesting Requ¡rements
7.3.6.1 Th¡s hydrostatic test of the tank shall be conducted before permanent extemal pip¡ng is connected to the
tank. Attachments to the shell defined in 5.8.1.'1, located at least 1 m (3 ft) above the water level, and roof
appurtenances may be welded during the filling of the tank. After completion of the hydro-test,.only non-structural
trall anu"hments inay be welded to-ttre tant in accordance with 7 .2.1.12- Any welded joints above the test-water
level shallbe examined for leakage by one ofthe following rnethods:
1) apply¡ng a h¡ghly penetrat¡ng oil on all inter¡or weld joints, e.g. automob¡le spring oil, and carefully examin¡ng the
orrtside of thejo¡nts for leakage;
2) applying vacuum ro e¡ther s¡de of thejoints or apply¡ng internal air pressure as spec¡fied for the roof test ¡n 7.3.7
and carefully exam¡ning thejo¡nts for leakage; or
3) using any comb¡nation of the methods stipulated ¡n Subitems 1 and 2.
7.3.6.2 The Manufacturer shall be responsible for the follow¡ng.
1) prepar¡ng the tank for tesring. Th¡s shall include removal of all trash, debr¡s, grease, o¡1, weld scale, weld'
.puüer, "ád
any other foreign matter from the ¡nterior and the roof(s) of the trnk'
. 2) Furnishing, lay¡ng, and remov¡ng all l¡nes from the water source t¡e-¡n location and to the water d¡sposal Po¡nt as
prescribed on the Data Sheet, Line 14.
. 3) F¡ll¡ng and empry¡ng the tank. (See 1.3 for Purchaser respons¡bility to obta¡n any required permits for d¡sposal of
water.)
. 4) Cleaning, rinsing, drying, or other prescribed activ¡ty, if specmed on Data Sheet, Line 14, follow¡ng the hydro-
test to make the tank ready for operation.
. 5) Tak¡ng se ement measurements (unless explicitly wa¡ved by the Purchaser on the Data Sheet, L¡ne 14).
6) Furnishing allother test mater¡als and faciliües, including bl¡nds, bolting, and gaskets (see 4.9).
. 7) Checking the wind girders for propef dra¡nage during or following the hydro-test. lf water is retained, additional
dra¡nage shall be prov¡ded subject to the Purchaser's approval.
. 7.3.6,3 The Purchaser shall be responsible for the follow¡ng.
l) Fumish¡ng and d¡spos¡ng of úle water for hydrGtestirE the tank ftom the water source tie-in location as'
designateá on the óata §heet, L¡ne 14. lf biocide or caustic additions are specified to the ManÚacturer, thepurc-haser is respons¡ble for determin¡ng or identify¡ng disposal resúict¡ons on the úeated water.
2) Specify¡ng the test water quality. Potable water ¡s prefered for hydro-testing. Th¡s does not.preclude lhe use of
condeñsate. reverse osmosis water, well water, river water, or sea water. The Purchaser shall consider issues
such as{ow temperature briüe fracture, freeze damagq amount of suspended sol¡ds, sanitation ¡ssues, animau
plant incubaüoñ and/or groMh, ac¡dity, general corrosion, p¡tting, protect¡ng aga¡nst . cathodic cells.
microbiologically-induced cónosion, material dependent sensiüvity to trace chemical attack, d¡sposal, r¡nsing,
API SfANDARD 650
and res¡duals left ¡n the tank after emptying. lf the Purchaser-supplied test water causes corros¡on, thePurchaser is responsible for the required repa¡rs.
3) For the follo\ ring rnetallurgies, describe on the Data Sheet, Line 14, (using a Supplemental Specificat¡on) anyadd¡tional restr¡ctions on the water quality.
a) Carbon §eel-For carbon steel equ¡pment where water contacl exceeds 14 days, including fill¡ng anddra¡n¡ng (e.9. cons¡der adding an oxygen scavenger and a b¡ocide, and ra¡se the pH by the addit¡on ofcaustic).
b) Sta¡nless Steel-See Annex S.
c) Aluminum Components-See Annex H.
7.3.6.4 For carbon and low-alloy steel tanks, the tank metal temperature dur¡ng hydrostatic testing shall not becolder than the des¡gn metal temperature per F¡gure 4.1, as long as the water ¡s prevented from freez¡ng. TheManufaclurer ¡s responsible for heaüng the test water, if heating is required, unless stated otherwise on the DataSheet, Line 14.
. 7.3.6.5 The minimum fill and discharge rate, if any, shall be specified by the Purchaser on the Data Sheet, Line 23.When settlement measurements are specified by the Purchaser, the maxlmum l¡lling rates shall be as follows, unlessotherwise restricted by the requ¡rements in 5.8.5.
Water F¡ll¡ng Rate
Bottom Cou6e Thickness Tank Ponion Max¡mum F¡ll¡ng Rate
Less than 22 mm (7/8 ¡n.)- Top course
- Below lop course
300 mm (12 in.)/hr
460 mm (18 ¡n.)/hr
22 mm (7/B ¡n.) and th¡cker
- Top th¡rd of tank
- Middle third of tank
- Bonom third of tank
230 mm (9 in.)/hr
3O0 (12 ¡n.)ihr
460 (18 in.)/hr
F¡ll¡ng may continue wh¡le elevaüon measurements are be¡ng made as long as the change ¡n water elevation for a setof readings does not exceed 300 mm (12 ¡n.). Unless waived on the Data Sheet, the Manufacturer shall make shellelevation measurements in accordance with the following.
a) Shell elevat¡on measurerrents shall be made at equally-spaced intervals around the tank circurnference notexceeding 10 m (32 ft). The min¡mum number of stell measurement po¡nts shall be e¡ght.
b) Observed elevations shall be referred to a permanent benchmark. The level instrument shall be set up at least11/2 times tank diameter away from the tank when tank elevaüon readings are taken. Six ses of settlementread¡ngs are required:
1) Before stan of the hydrostatic test;
2) With tank f¡lled to lk test height (1600 mm [2 ftl);
3) With tank l¡lled to 1/2 test height (1600 mm [2 ftl);
4) With tank f¡lled to 3/4 test height (i6oo mm [2 ftD;
1-8
WELDED TaNxs FoR OtL SToRAGE
\/ 5) At least 24 hours after the tank has been filled to the maximum test height. Th¡s 24-hour period may be
incre¿sed to durat¡on specified on the data sheet if the Purchaser so requires for condit¡ons such as:
i. The tank is the f¡rst one ¡n the area,
¡¡. The tank has a larger capac¡ty than any other ex¡sting tank in the area,
i¡¡. The tank has a h¡gher unit bearing load than any other existing tank in the area,
iv. There ¡s a question regarding the rate or rnagn¡tude of setüement that will take place;
6) After tank has been emptied of test water.
. NOTE The three sels of settlemert readings described ¡n paragraphs 2, 3, and 4 above may be omitred if specmed by thePurchaset
7.3.6.6 lf setüement measurements are specif¡ed by the Purchase¡ any differenüal settlernent gfeater üan 13 mm
per 10 m (1/z in. per 32 ft) of circumference or a unifom senlement over 50 mm (2 ¡n.) shall be reported to the
Purchaser for evalualion. Filling of the tank shall be stopped unt¡l cleared by the Purchaser.
7.3.6.7 For floating-roof tanks, the maximum and minimum annular space between the shell and the roof rim plate
p{¡or to initial flotat¡on and at the max¡mum test f¡ll he¡ght shall be measured and recorded.
7.3.6.8 lntemal bottom elevation measurements shall be made before and after hydrostatic tesling. Measurements
shall be made at maximum intervals of 3 m (10 ft) measured on diarnetrical lines across the tank. The d¡ametrical
lines shall be spaced at equal angles, wiü a max¡mum separat¡on measured at the tank circumference of 10 m (32 ft).
A minimum of four diametrical l¡nes shall be used.
\- 7,3.6.9 All elevation rneasurements shall be included in the Manúacturer's Post-Consúucüon Docurnent Package(see W.1.5).
7.3.7 Testing of the Roof
7.3.7.1 Upon completion. the roof of a tank designed to be gas{ight (except for roofs designed under 7 .3.7 .2, F.4.4,
and F.7.6) shall be tested by one of the following methods.
a) Applying intemal air pressure not exceeding the weight of the roof plates and applying to the weld jo¡nE a bubble
solut¡on or other material suitable for the detection of leaks.
b) Vacuum testing the weld joints ¡n accordance with 8.6 to detect any leaks.
. 7.3.7.2 Upon completion, the roof of a tank not des¡gned to be gas-t¡ght, srrch as a ütnk with peripheral circulation
vents or a tank with free or open vents, shall receive only visual exam¡nation of its weld jo¡n§, unless otherw¡se Ispecified by the Purchaser.
7.4 Repa¡rs to Welds
. 7,4.1 All defects found ¡n welds shall be cálled to the attenüon of the Purchaser's ¡nspector, and the ¡nspector§approval shall be obtained before the defects are repa¡red. All completed repairs shall be subject to the approval ofthe Purchaser's ¡nspector. Acceptance criteria are specif¡ed ¡n 8.2, 8.4, and 8.5, as applicable.
7.¡t.2 P¡nhole leaks or porosity ¡n a tank bonom joint may be repa¡red by applying an add¡tional weld bead over thedefective area. Other defects or cracks ¡n tank bottom or tank roof (¡ncluding floaüng roofs ¡n Annex C) jo¡nts shall berepaired as requ¡red by 8.1.7. Mechanical caulking is not permmed.
\- 7.4.3 All defects, cracks, or leaks in shelljo¡nts or the shell-to-bottom jo¡nt shall be repa¡red in accordance with 8.1.7.
7-10 API STANDARo 650
7.4.4 Repairs of defects d¡scovered after the tank has been f¡lled with water for testing shall be made with the waterlevel at least 0.3 m (1 ft) below any point be¡ng repaired or, ¡f repairs have to be made on or near the tank bottom, withthe tank empty. Welding shall not be done on any tank unless all connecting lines have been completely blinded.Repairs shall not be attempted on a tank that ¡s f¡lled with oil or that has conta¡ned oil until the tank has been empüed,cleaned, and gas freed. Repairs on a tank that has conta¡ned oil shall not be attempted by the Manufacturer unlessthe manner of repair has been approved ¡n wr¡t¡ng by the Purchaser and the repa¡rs are made in the presence ofthePurchaser's inspector.
7.5 DimensionalTolerances
7.5.1 General
The purpose of the tolerances given in 7.5.2 through 7.5.7 is to produce a tank of acceptable appearance and topermit poper functioning of float¡ng roofs. Measurements shall be taken prior to tlle hydrostatic water test. Unlesswaived or mod¡fed by the Purchaser on Data Sheet, L¡ne 15, or established separately by agreement between thePurchaser and the Manúacturer, üe following tolerances apply.
7.5.2 Plumbness
a) The maximum out-of-plumbness of the top of the shell relat¡ve to the bottom of the shell shall not exceed 1/2oo ofthe total tank height. The out-of-plumbness in one shell course shall not exceed the perm¡ssible variations forflatness and wav¡ness as specif¡ed ¡n ASTM AOÍWA6, ASTM A20lvUA20, or ASTM A4801WA480, wh¡chever isapplicable.
b) The maximum out-of-plumbness of roof columns, gu¡de poles, or other vert¡cal intemal components shall notexceed 1/zoo of the total he¡ght. The 1/2OO criteria shall also apply to fixed roof columns. For tanks with internalfloaüng roofs, apply the criteria of th¡s sect¡on or Annex H, wh¡chever is more stringent.
7.5.3 Roundness
Radi¡ measured at 0.3 m (1 ft) above the bottom corner weld shall not exceed the following tolerances:
Tank D¡ameterm (ft)
Rad¡us Tolerancemm (in.)
< 12 (40)
Fmm 12 (40) to < 45 (150)
From 45 (150) to < 75 (250)
> 75 (25O)
1 13 (1/2)
a 19 (3/1)
r 2s (l)
! 32 (1111)
7.5.4 Local Dev¡ations
Local dev¡ations from the theoretical shapefollows.
(for example, weld d¡scontinuities and flat spots) shall be limited as
a) Deviaüons (peaking) at vertical weld joints shall not exceed 13 mm (1/2 in.). Peak¡ng at vertical weld jo¡nts shall bedeterm¡ned us¡ng a hor¡zontal sweep board 90O mm (36 in.) long. The sweep board shall be made to the nom¡nalradius of the tank.
b) Dev¡at¡ons (band¡ng) at horizontal weld jcúnts shall not exceed 13 mm (1/2 ¡n.). Banding at horizontal weld jo¡ntsshall be determined us¡ng a straight edge vertical sweep board 900 mm (36 ¡n.) long.
c) Flat spots measured ¡n the vertical plane shall not exceed the appropriate plate flatness and wavinessrequ¡rements g¡ven in 7.5.2.
W€TOEO fANKS fOR O[ STORAGE 7.11
\' 7.s.5 Foundations
7.5.5.1 To achieve the tolerances specified ¡n 1 .5.2, 7 .5.3, and 7.5.4, it ¡s essential that a foundat¡on tfue to the
plane be prov¡ded for the tank erection. The foundat¡on should have adequate bearing to rnaintain the trueness of the
foundaüon (see Annex B).
7.5.5.2 Where foundations true to a horizontal plane are specmed, tolerances shall be as follov.'s.
a) where a concrete ringwall is provided under the shell' the top of the ringvvall shall be level with¡n 13 mm (1/8 ¡n ) in
any 9 m (ao 0 of thÉ c¡rcumference and within 16 mm (1i¿ in.) in thé total circumference measured from the
averaqe elevation.
b) Where a concrere ringwall is not prov¡ded, the foundation under the shell shall be level within t3 mm (1/e in') in
any 3 m (10ft) of the cúcumference and within r13 mm (1/z in.) in the total circurnference rneasured from the
average elevation.
c) whefe a concrete slab foundaüon ¡s prov¡ded, the first 0.3 m (1 ft) of the foundaüon (or width of the annular ring)'
measured from the ouSide of the iank radially towards the center, shall comply with the concrete ringwall
requ¡rement. The rema¡nder of the foundation sháll be with¡n r'13 mm (1/z in.) of the design shape'
7.5.5.3 Where a sloping foundation ¡s specified, elevation diffefences about the circumference shall be calculated
from the spec¡f¡ed n¡gh'ñ;¡"i. Á"t r"l "l"i,ution
oitr"r"n es aboü the circumference shall be determined from the
actual elevat¡on "f
thJ +;iiJ hish point. The actual elevat¡on differences shall not dev¡ate from the calculated
d¡fierences by more than the following tolerances
a) where a concree ringwall is pfov¡ded, 13 mm (1/8 in.) in any I m (30 ft) of circumference and t6 mm (1/l in ) in the
\-, total circumference'
b) where a concrere ringwall ¡s not pfovideil, t3 mm (1/s in.) in any 3 m (10 ft) of circumfefence and tl3 mm (1/2 in )
in the total circumference.
7.5.6 Nozzles
Nozzles (exclud¡ng manholes) shall be ¡nstalled within the folloÚng tolerances:
a)specifiedpoject¡onfiomoutsideoftankshelltoextfemefaceofflange:15mm(3h6in.);
b)elevationofshellnozzleorradiallocationofaroofnozzle:rGmm(1/4¡n);
c) flange t¡lt in any plane, measured on the flange face:
r1lz degree for nozzles greater than NPS 12 in nom¡nal d¡ameter'
13 mm (1/s in.) at the outs¡de flange d¡ameter for nozzles NPS 12 and smaller;
d) flange boh hole or¡entat¡on: t3 mm (1/8 ¡n')'
?.5.7 Shell Manholes
Manholes shall be ¡nstalled within the following tolerances:
a) specified projection from ou6ide of shell to extrerne face of flange' t13 mm (1/z in )
b) elevation and angular location, i'|3 mm (1/2 in )
\-. c) flange ült in any plane, measured across üe flange d¡arnetef, 113 mm (1/2 in.)
SECTION HTIETHODS OF EXAMINING JOINTS
NOTE ln this standard, the term ¡nspeclor, as used in sections v and vlll of the ASME Code, shall be intefpreted to rnean the
Purchaser's inspector.
8.1 Rad¡ograph¡cMethod
For the purposes of th¡s paragraph, plates shall be considered of the same thickness when the diñerence ¡n the¡r
specifi«i ordesign th¡ckness does not exceed 3 mm (1/8 in.).
8.1.1 Application
Rad¡ograph¡c exam¡nation ¡s requ¡red for shell br¡tt-welds (see 8.1.2.2, 8.1.2.3, and 8.1.2.4), annular-plate butt-welds
(see g:l.á.g), an¿ Rush-§pe conneclions w¡th bun-welds (see 5.7.8.11). Rad¡ographic exam¡nation ¡s not requked for
üe fottowing: roof-ptate óáUs, bonom-plate welds, welds jo¡n¡ng the top angle to either the roof or shell, welds join¡ng
ttre shell plaie to tü bonom plate. welds ¡n nozzle and manway necks made from plate, or appurtenance welds to the
tank.
8.1.2 Number and Locat¡on of RadiograPhs
g.1.2.1 Except when omined under the prov¡s¡ons of A.3.4, rad¡ographs shall be taken as sPcif¡ed in 8.1.2 through
8.1.9.
8.1.2.2 The following requ¡rements apply to verticaljoints.
a) For butt-welded joints in wh¡ch the th¡nner shell plate is less than or equal to 10 mm (3/8.¡n.) ü¡ck, one spot
rad¡ograph shall-be taken in üre first 3 m (10 ft) of completed verticaljoint of each type and th¡ckness welded by
eachivelder or weld¡ng operator. The spot rad¡€raphs taken in the verticaljo¡nts of the lowest course may be
used to meet the reqúirements of llotá g in Figure 8.1 for individual joints. Thereafter- without regard to the
number of welders or welding operators, one addiüonal spot radiograph shall be taken in each.addiüonal 30 m
(1OO ft) (approximately) and a;y;ema¡ning major fraction of venicaljo¡nt of the same §Pe and üickness. At least
)s "¡ ói t¡á sebcted-spors snátt fe at.¡unaións of vertical and horizontal jo¡nts, with a min¡mum of two such
intersections per tank. ;n addiüon to üe forego¡ng requirements, one random spot rad¡ograph shall be taken ¡n
each verticaljoint ¡n the lowest course (see the top panel of F¡gure 8.1).
b) For hrtt-welded joints in wh¡ch the thinner shell plate ¡s greatef than 10 mm (3/8 in.) hrt less than or equal to
25 mm (t ¡n.) in thickness, spot rad¡ographs shall be taken according to ltem a. ln addiüon, alljunctions of venical
and horizon6ljoints in plates ¡n th¡s úickness range shall be radiographed; each flm shall clearly show not less
than 75 mm (3 in.) of vert¡cal weld and 50 mm (2 ¡n.) of weld length on each s¡de of the vert¡cal intersection. ln the
lowest course, two spot radiographs shall be taken in each vert¡caljoint one of the radiograPhs_shall be as close
to the bonom as ¡s páaicaUtel ,irA me other shall be taken at random (see the center Panel of F¡gure 8.1).
c) Verr¡caljoinrs ¡n which the shell plares are greater than 25 mm (1 in.) thick shall be fully rad¡ographed. Alljunct¡ons' of veniál and horizontaljoints ¡ir th¡s th¡ckñess range shall be rad¡ographed; each f¡lm shall cleariy show not less
than 75 mm (3 in.) of venical weld and 50 mm (2 ¡n-.) of weld length on each side of the veftical intefsecüon (see
the bottom panel of F¡gure 8.1).
O The butt-weld around the per¡phery of an ¡nsen plate that extends less than the adjacent shell course he¡ght and
that contains shell openiñg (i.e.-nozzle, manway, flush-type cleanort, flush §Fe shell'connection) and the¡r
re¡nforc¡ng elements shalt be comdetely radiographed.
8-1
8-2 API SfANDARD 650
E l 50 mm (2 ¡n )-.rn
2 1
Ilso mm (6iñJ[¡
:i:rt
r---r--r----l_1t-fi,o * p^,n.¡ r",,r,, I
l r_l150 mm (6 in.)l 3
r -'l
Top of shelll (Numbers ¡n squares refer to notes below)
fank bottom
Top or shell _} Plate Th¡ckness f 10 mm (Y3 ¡n.)
t0 ñrn (3/r ¡n.) < Plate Thicknsss s 25 rÍrñ ('l ¡n.)
rant ¡onom J Plate Th¡ckness > 25 mm (1 ¡n.)
tlotes:
1. Vertical spor radbgraph in accordance with 8,1.2.2. ltem ar one h üle f¡§ 3 m (10 ft) and one h each 30 m (100 i) thereafrer,25 % ol wt*,l shal be at irtersecliorE.
2. fbizo al spot radbgraph in codance wilh 8.1.2.3: one in lñe ñrsl 3 m (t0 ñ) and ooe in each 60 m (2@ ñ) thereafrer.
3. Venical spot radbgratñ in each vertaal seam ¡n the lowest course Isee 8.1.2.2, ltem b). Spot radiivaphs üat satjsfy ülerequ¡reÍ¡ents ol Note 1 for lhe lowes couse may be used to sat¡sfy lhis requ¡rement.
1. Spot radbgrapi¡s of all ¡ntersecrbns over 1O mm (3/s ¡n.) (see 8.1.2.2, ltem b).
5. Spot radbgaph ot bonom of eeh velticalseam ¡n lourest shell couse ove.10 nyn (3/s ¡n.) (see 8.1.2.2. ltem b).
6. Comdete rad¡ocaph of each vertcal seam over 25 mm (1 ¡n.). The comdere rad¡ogfaph may irrclude ü|e spot rad¡ographs oa
üe interseclion§ it itle f¡lm has a mirimum width of lm mm (1 ¡n.) (see 8.1.2.2, ltem c).
e
'.10 mm (3/s ¡n.)
50 mm (2 in.)
25 mm (l ¡n.) max¡mum
s 25 mm (1 ¡n.)
> 25 mm (1 in.)
F¡gure 8.1-Radiographic Requirements for Tank Shells
> 10 mm (% ¡n.)
> 10 mm (3/s ¡n.)
WELDED faNKs FoR OrL SToRAGE 8-3
e) The butt-weld around the periphery of an insert plate which extends to match the aq,acent shell course heightshall have the venical and the horizontal butt joints and the intersections of vertical and horizontal weld jo¡nts
radiographed using the same rules that apply to the weldjoints ¡n adjacent shell plates in the same shell course.
8.1.2.3 One spot radiograph shall be taken ¡n the first 3 m (10ft) of completed horizontal buttjo¡nt of the same typeand thickness (based on the üickness of the thinner plate at thejoino w¡thout regard to the number of welders orwelding operators. Thereafter, one rad¡ograph shall be taken ¡n each addiüonal 60 m (200 ft) (approx¡mately) and anyrema¡ning major fract¡on of hor¡zontaljo¡nt of the sarne type and th¡ckness. These rad¡ographs are in addition to theradiographs ofjunctions of verticaljoints required by ltem c of 8.1 .2.2 (see F¡gure 8. 1).
8.1.2.4 The number of spot rad¡ographs required here¡n shall be appl¡cable on a per tank basis, inespective of thenumber of tanks being erected concurently or continuously at any locat¡on.
8.1.2.5 lt ¡s recogn¡zed that in many cases the same welder or welding operator does not weld both sides of a buttjo¡nt. lf two welders or weld¡ng operators weld opposite sides of a butt jo¡nt it ¡s permissible to examine the¡r work w¡th
one spot radiograph. lf the radiograph is rejected, add¡t¡onal spot radiographs shall be taken to determ¡ne whetherone or both of the welders or welding operators are at fault.
8.1.2.6 An equal number of spot radiographs shall be taken fiom the work of each welder or welding operator inproportion to the length ofjoints welded.
8,1.2.7 As welding progresses, rad¡ographs shall be taken as soon as it is pract¡cable. The locat¡ons where spotradiographs are to be taken may be determined by the Purchasers inspector.
8.1.2.8 Each radiograph shall clearly show a m¡nimum of 150mm (6 in.) of weld length. The film shall be centeredon the weld and shall be of srifficient w¡dth to permit adequate space for the locaüon of ¡denüf¡cat¡on marks and animage quality ind¡cator (lQl) penetrometer
8.1.2.9 When bottom annular plates are required by 5.5.1, or by M.4.1, the radialjoints shall be radiographed asfollows: (a) For double-welded buttjoints, one spot rad¡ograph shall be taken on 10 o/o of the radialjolnts; (b) Forsingle-welded buttjo¡nts with permanent or removable back-up bar, one spot rad¡ograph shall be taken on 50 % of therad¡al joints. Extra care must be exercised in the interpretation of radiographs of single-welded joins that have a
permanent back-up bar. ln some cases, addiüonal exposures taken at an angle may determine whether questionable¡nd¡cations are acceptable. The minimum radiograph¡c length of each radialjoint shall be 150 mm (6 in.). Locations ofradiographs shall preferably be at the outer edge of thejoint where the shell plate and annular platejo¡n.
8.1.3 Techn¡que
8.1.3.1 Except as modified in this sect¡on, the radiographic examinat¡on method employed shall be ¡n accordancewith secüon v, Anicle 2, of the ASME code.
8.1.3.2 Personnel who pelorm and evaluate rad¡ographic examinaüons according to this sect¡on shall be qualif¡edand cenif¡ed by the Manufacturer as meeting the requirements of certif¡cation as generally outl¡ned ¡n Level ll or Levellll of ASNT SNT-TC-1A (including applicable supplemens). Level-l personnel may be used if they are g¡ven writtenacceptance/rejection procedures prepared by Level-ll or Levellll personnel. These wr¡nen procedures shall conta¡nthe appl¡cable requ¡rements of Secüon V, Anicle 2, of the ASME Code. ln addition, all Level-l personnel shall be underthe d¡rect supervision of Level-ll or Level-lll personnel.
8.'1.3.3 The requirements of T-285 ¡n Section V Article 2, of the ASME Code are to be used only as a gu¡de. F¡nalacceptance of rad¡ographs shall be based on whether the prescr¡bed pen et ramet er ¡mage and the specif¡ed holecan be seen.
API SfANoARo 650
8.1.3.4 The f¡n¡shed surface of the weld reinfo.cement al the location of the rad¡ograph shall either be flush w¡th theplate or have a reasonably uniform crown not to exceed the following values:
PlateThicknessmm (¡n.)
Maximum Thickness ofRe¡nforcement
mm (in.)
< 13 (1/z)
> 13 (1/2) to 25 (1)
> 25 (1)
1.5 (1/r6)
2.5 (3h21
3 (1/8)
8.1.4 Submission of Radiographs
Before any welds are repaired, the rad¡ographs shall be submitted to the inspector with any ¡nfonnat¡on requested bythe ¡nspector regard¡ng the radiographic techn¡que used.
8.1.5 Rad¡ograph¡c Standards
Welds examined by radiography shall bejudged as acceptable or unacceptable by the standards of Paragraph UW-
51(b) in secr¡on vlll of the ASME code.
8.1.6 Determination of Lim¡ts of Defect¡ve Welding
When a sect¡on of weld ¡s shown by a radiograph to be unacceptable under the provisions of 8.1.5 or the l¡m¡ts of thedef¡c¡ent welding are not defined by the radiograph, two spots adjacent to the seclion shall be exam¡ned byradiography; however, if the original radiograph shows at least 75 mm (3 ¡n.) of acceptable weld between the defectand any one edge of the f¡lm, an add¡t¡onal radiograph need not be taken of the weld on that side of the defect. lf theweld at either of the adjacent sect¡ons fails to comply w¡th the requirements of 8.1.5, add¡t¡onal spots shall beexamined until the limits of unacceptable welding are determ¡ned, or the erector may replace all of the weldingperformed by the welder or welding operator on that joint. lf the weld¡ng ¡s replaced, the ¡nsPeclor shall have theopüon of requiring that one rad¡ograph be taken at any selected location on any otherjo¡nt on which the same welderor weld¡ng operator has welded. lf any of these additional spots fail to compy with the requ¡rements of 8.1.5, the limits
of unacceptable welding shall be determined as specif¡ed for the initial section.
8.1.7 Repair of Defective Welds
8.1.7.'l Defects in welds shall be repaired by chipping or melting out the defects from one side or both s¡des of thejo¡nt, as required, and reweld¡ng. Only the cutt¡ng out of defect¡ve joints that ¡s necessary to corect the defects isrequ¡red.
8.1.7.2 All repaired welds in joints shall be checked by repeaüng the orig¡nal examination procedure and byrepeafng one of the te§t¡ng methods of 7.3, sutiect to üe aPproval of tfle Purchaser.
8.1,8 Record of Radiographic Examination
8.1.8.1 The Manufacturer shall prepare a radiograph map showing the f¡nal locaüon of all radiographs taken alongwith ttle f¡lm idenüfication marks.
. 8.1.8.2 After the structure ¡s completed, the f¡lrm shall be the property of the Purchaser unless otherw¡se agreedupon by the Purchaser and the Manufacturer.
'l
WEIoED TaNKS FoR OrL SToFiAGE
\7 8.2 Magnet¡c Part¡cle Exam¡nation
8.2.1 When magnetic part¡cle exam¡nat¡on is specified, the method of examination shall be in accordance withSect¡on V Article 7, of the ASME Code.
8.2.2 Magnet¡c particle exam¡nation shall be performed in accordance with a written procedure that is certified bythe Manúacturer to be in compliance with üe applicable requirements of Section V of the ASME Code.
8.2.3 The Manufacturer shall determine that each magnetic particle examiner meeE the follow¡ng requirements.
a) Has v¡sion (wiü conection, if necessary) to be able to read a Jaeger Type 2 standard chart at a d¡stance of notless than 300 mm (12 ¡n.) and is capable of d¡stingu¡sh¡ng and differenüating conrast between the colors used.Exam¡ners shall be checked annually to ensure tha¡ they meet these requ¡remenE.
b) ls competent ¡n the technique of the magnetic part¡cle examinat¡on method, including performing the exam¡nationand interpreüng and evaluating the results; however, where the exam¡nat¡on rnethod consists of more than oneoperation, the examiner need only be qualmed for one or rnore of lhe operat¡ons.
8.2.4 Acceptance standards and the removal and repa¡r of defects shall be ¡n accordance with Section Vlll, Annex6, Paragraphs 6-3, 6-4, and 6-5, of the ASME Code.
8.3 UltrasonicExamination
8.3.1 Ultrasonic Examinat¡on in Lieu of Radiography
. When u¡trason¡c examination is applied in order to fulf¡ll the requirement ú 7 .3.2.'1, the provisions of Annex U shall\- appty.
8.3.2 Ultrason¡c Examinat¡on NOT in Lieu of Radiography
8.3.2.1 When the radiographic rnethod is appl¡ed ¡n order to fulf¡ll the requirement oÍ 1.3.2.1, then any u¡trasonicexamination specmed shall be ¡n accordance with this section.
8.3.2.2 The method of exam¡naüon shall be ¡n accordance w¡th Section V Article 4, of the ASME Code.
8.3,2.3 Ultrasonic examinaüon shall be perfomed in accordance wih a written procedure that is certified by theManufacturer to be in compliance with the appl¡cable requ¡rements of Seclion V of the ASME Code.
8.3.2.4 Examiners who perform ultrason¡c examinat¡ons under this section shall be qualified and certif¡ed by theManufacturers as meeting the requ¡rements of certif¡cat¡on as generally outlined ¡n Level ll or Level lll of ASNT SNT-TC-1A (¡nclud¡ng applicable supplernen6). Level-l personnel may be used if hey are given wrinen acceptance/rejection criteria prepared by Level-ll or Level-lll personnel. ln addit¡on, all Level-l personnel shall be under the d¡rectsupervis¡on of Level-ll or Level-lll personnel.
. 8.3.2.5 Acceptance standarG shall be agreed upon by the Purchaser and the Manufacurer
8.4 Liquid Penetrant Exam¡nation
8.4.1 When liquid penetrant examination ¡s specified, the method of examination shall be ¡n accordance w¡thsect¡on v Article 6, of the ASME code.
8.4.2 L¡qu¡d penetrant examinaüon shall be performed in accordance with a written procedure that ¡s cerlif¡ed by the
\_ Manufacturer to be in compliance with the appl¡cable requ¡rements of Section V of the ASME codé.
API STANDARo 650
8./t.3 The Manufacturer shall determine and certify that each l¡qu¡d penerant examiner meets the follow¡ngrequirements.
a) Has vision (w¡th corection, if necessary) to enable h¡m to read a Jaeger Type 2 standard chart at a distance of notless than 300 mm (12 in.) and ¡s capable of d¡süngu¡shing and d¡fferentiating contrast between the colors used.Examiners shall be checked annually to ensure that they meet these requ¡rements.
b) ls competent in the techn¡que of the liquid penetrant examinaüon method for wh¡ch he ¡s certif¡ed, includingmaking the examinaüon and ¡nterpreting and evaluating the results; however, where the exam¡nat¡on methodcons¡sts of more than one operation, the examiner may be cert¡fied as being qualif¡ed for one or more of theoperat¡ons.
8,4.4 Acceptance standards and üe removal and repa¡r of defects shall be ¡n accordance with Sect¡on Vlll, Annex8, Paragraphs 8-3, 8-4, and 8-5, of the ASME Code.
8.5 v¡sual Exam¡nat¡on
8.5.1 The Manufacturer shall determine and certify that each visual examiner meets the following requiremen§.
a) Has v¡s¡on (wiü conection, if necessary) to be able to read a Jaeger Type 2 standard chart at a d¡stance of notless üan 300 mm (12 in.) and ¡s capable of pass¡ng a color contrast test. Exam¡ners shall be checked annually toensure that they meet th¡s requirernenu and
b) ls competent ¡n the technique of üe visual examinaüon, ¡nclud¡ng performing the examinat¡on and interpreting andevaluating the resuhs; however, where the examination rnethod consists of more than one operation, theexam¡ner performing only a portion ol the test need only be qualif¡ed for the port¡on that the examiner performs.
8.5.2 A weld shall be acceptable by visual exam¡nation if the inspecüon shows the following.
a) There are no crater cracks, other surface cracks or arc str¡kes ¡n or adjacent to the weldedjoints.
b) Maximum permissible undercut ¡s 0.4 mm (1/64 in.) in depth for vertical buttjoints, vertically oriented permanentattachments, attachment welds for nozzles, manholes, flush-type open¡ngs, and the ins¡de shell-to-bottom welds.For horizontal buttjo¡nts, horizontally oriented pennanent attachments, and annular-ring buttjo¡nts, üe maximumpermissible undercut ¡s 0.8 mm (U:z in.) in depth.
c) The frequency of surface poros¡ty in the weld does not exceed one cluster (one or more pores) in any 100 mm(4 in.) of length, and the d¡ameter of each cluster does not exceed 2.5 mm (3/gz in.).
O The re¡nforcement of the welds on all butt jo¡nts on each side of the plate shall not exceed the follow¡ngthicknesses:
Plate Thicknessmm (in.)
Max¡mum Reinforcement Thicknessmm (¡n.)
Vert¡cal Joints Hor¡zontal Jo¡nts
< 13 C/2)
> 13 (1/2) to 25 (1)
> 25 (1)
2.s 1s1.r,
3 (1/s)
5 (3^6)
3 (1/8)
5 (3/16)
6 (1A)
\ /ELoEo TANKS FoR OtL SToRAGE
The reinforcement need not be removed except to the extent that it exceeds the max¡mum acceptable hickness orunless its removal ¡s required by 8.1.3.4 for rad¡ographic exam¡nation.
8.5.3 A weld that Fa¡ls to meet the criteria given ¡n 8.5.1 shall be reworked before hydrosiat¡c testing as follows:
a) Any defecis shall be removed by mechanical means or thermal gouging processes. Arc strikes discovered ¡n oradiacent to welded jo¡nts shall be repa¡red by grind¡ng and rewelding as requ¡red. Arc stikes repaired by weldingshall be ground flush with the plate.
b) Rewelding is requ¡red if the resulting th¡ckness ¡s less than the m¡n¡mum required for des¡gn or hydrostat¡c testcondit¡ons. All defecls ¡n areas th¡cker than the m¡n¡mum shall be feathered to at least a 4:l taper.
c) The repa¡r weld shall be üsually examined for defec{s.
DELETED
8.6 Vacuum Tesüng
8.6.1 Vacuum test¡ng is performed using a test¡ng box approximately 150 mm (6 in.) w¡de by 750 mm (30 in.) longwith a clear w¡ndow in the top, which prov¡des proper visibility to v¡ew the area under exam¡nation. Dur¡ng test¡ng,¡lluminaüon shall be adequate for proper evaluaüon and ¡nterpretation of the test. The open bottom shall be sealedagainst the tank surface by a suitable gasket. Connec{ions, valves, l¡ght¡ng and gauges, as required, shall beprovided. A soap lllm solulion or commercial leak delection solution, appl¡cable to the conditions, shall be used.
8.6.2 Vacuum test¡ng shall be performed ¡n accordance w¡th a written procedure prepared by the Manufacturer ofthe tank. fhe procedure shall require:
a) pelorm¡ng a v¡sual examination of the bottom and welds prior to perform¡ng the vacuuñF,box test;
b) verirying thé condit¡on of lhe vacuum box and its gasket seals;
c) veriry¡ng that there is no quick bubble or spitt¡ng response to large leaks; and
d) applying the film solution to a dry area, such that the area ¡s thoroughly wetted and a min¡mum generation ofappl¡cat¡on bubbles occurs.
8.6.3 A partial vacuum of 2'l kPa (3 lbíin.2, 6 in. Hg¡ to 35 kPa (5 lbfin.2, 1O in Hg) gauge shall be u§ed for the test.If specified by the Purchaser, a second part¡al vacuum test of 56 kPa (6 lbfl¡n.2, '16 ¡n. Hg) to 70 kpa (10 lbí¡n.2, 20 in.Hg) shall be performed for the détecl¡on of very small leaks.
8.6.4 The Manufacturer shall determine that each vacuum-box operator meets the following requ¡remen§:
a) has vis¡on (with corecl¡on, ¡f necessary) to be able to read a Jaeger Type 2 standárd chart at a d¡stance of not lessthan 300 mm (12 ¡n.). Operators shall b€ checked annually to ensure that they meet this requ¡rement; and
b) is competent in the techn¡que of lhe vacuum-box lest¡ng, ¡ncluding performing the exam¡nat¡on and ¡nterpreüngand evaluating the results; however, where the examination method mnsists of more than one operat¡on, theoperator perform¡ng only a portjon ofthe test need only be qual¡fied for that port¡on the operator performs.
8.6.5 The vaqJurr} box test shall have at least 50 mm (2 in.) overlap of previously v¡ewed surface on eachapplicat¡on.
API STANDARo 650
8.6.6 The metal surface temperature l¡m¡ts shall be beiween 4'C (40 "F) and 52 "C (125 "F), unless the flmsolut¡on ¡s proven to work al temperatures ouls¡de these limits, either by testing or Manufaciurer's recommendat¡ons.
8.6.7 A min¡mum light ¡ntensity of 1000 Lux (100 fc) at the po¡nt of exam¡nat¡on ¡s required dur¡ng the appl¡cat¡on ofthe exam¡nat¡on and evaluat¡on for leaks.
8.6.8 The vacuum shall be mainta¡ned for the greater of either at least 5 seconds or the time requ¡red to view thearea under test.
8.6.9 The presence of a through-th¡ckness leak ind¡cated by cont¡nuous formation or growth of a bubble(s) or foam,produced by air pass¡ng through the th¡ckness, ¡s unaccéptable. The presence of a large open¡ng leak, indicated by aquick bursüng bubble or sp¡tt¡ñg résponse at the initial setting of the vacuum box ¡s unacceptable. Leaks shall berepa¡red and retested.
8.6.10 A record or report of the test ¡ncluding a statement address¡ng témperature and l¡ght ¡ntensity shall becompleted and fum¡shed to the Purchaser upon request.
8.6.11 As an altemate to vácuum-box test¡ng, a suitable tracer gas and compatible detécior can be used to test theintegrity of welded bottom jo¡nts for the¡r entire length. Vv¡ere tracer gas test¡ng ¡s employed as an altemate tovacuum-box test¡ng, it shall meet the follow¡ng requ¡rements:
a) Tracer gas test¡ng shall be performed ¡n accordance with a written procedure which has been rev¡ewed andapproved by the Purchaser and wh¡ch shall address as a m¡n¡mum: the type of equipment used, surfacecleanliness, type of tracer gas, test pressure, so¡l permeabiliv, so¡l moisture content, satisfac,tory verifcat¡on oftheextent of tracér gas permeat¡on, and the méthod or techn¡que to be used includ¡ng scann¡ng rate and probestandofi d¡stance.
b) The technique shall be capable of detecl¡ng leakage of 1 x 1É Pa m3/s (1 x 10-3 std cm30 or smaller.
c) The test system parametérs (detector, gas, and systém préssure, i.e., level of pressure under bottom) shall becal¡brated by placing the appropr¡ate calibrated cap¡llary leak, wh¡ch will leak at a rate cons¡stent w¡th (b) above, ina temporary or permanent fitting ¡n the tank bottom away from the tracer gas pressurizing po¡nt. Altemaüvely, byagreement bet\¡veen the Purchaser and the Manufadurer, the calibrated leak may be placed ¡n a separate fitt¡ngpressurized ¡n accordance with the syslem parameters.
d) Vvh¡le test¡ng for leaks ¡n the welded bottom io¡nb, system parameters shall be unchanged from those used duringcal¡bration.
