spc cr ur 510 r03 e f L - National Fertilizers

$

Form code : MDT.GG.QUA.0505 Sh. 01/Rev. 1.94 File code: spcgnrae.dot Data file: spc_cr_ur_510_r03_e_f.doc

THE INFORMATION HEREIN AND IN THE FOLLOWING PAGES (N°35 , COVER INCLUDING) CONTAINED IS SECRET, CONFIDENTIAL AND BELONGS TO SNAMPROGETTI WHICH HAS

PROVIDED IT SOLELY FOR AN EXPRESSLY RESTRICTED PRIVATE USE. ALL PERSONS, FIRMS OR CORPORATIONS WHO RECEIVE SUCH INFORMATION FROM SNAMPROGETTI SHALL

BE DEEMED BY THEIR ACT OF RECEIVING THE SAME TO HAVE AGREED TO BE OBLIGED TO KEEP IT SECRET AND CONFIDENTIAL, TO MAKE NO DUPLICATION OR OTHER DISCLOSURE

OR USE WHATSOEVER OF ANY OR ALL SUCH INFORMATION EXCEPT SUCH RESTRICTED USE AS IS EXPRESSLY AUTHORIZED IN WRITING BY SNAMPROGETTI AND SOLELY FOR THE

SCOPE AGREED THEREIN. IN CASE OF UNDUE DISCLOSURE AND/ OR ANY FAILURE TO OBSERVE THE ABOVE PROVISIONS, THE DEFAULTING PARTY SHALL BE RESPONSIBLE FOR ANY

AND ALL DAMAGES, WITHOUT LIMITATIONS.

GENERAL SPECIFICATION

AUSTENITIC STAINLESS STEELS FOR UREA PLANT HIGH PRESSURE SECTION

SPC.CR.UR.510

Rev.03

September 2003

anish

Rectangle

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Rev. 03 Date Sep. 2003

Sheet 2 (24)

Form code : MDT.GG.QUA.0515 Sh. 01/Rev. 1.94 File code: spcgnrae.dot Data file: spc_cr_ur_510_r03_e_f.doc This document is the property of Snamprogetti who will safeguard its rights according to the civil and penal provision of the law.

C O N T E N T S

1 GENERAL 4

1.1 Scope and field of application 4

1.2 Definitions 4

1.3 Abbreviations 4

1.4 Referenced Codes (always latest revision) 5

2 MATERIALS 6

2.1 General 6

2.2 316L UG stainless steel (UNS S31603) 6

2.3 25Cr-22Ni-2Mo alloy (UNS S31050) 6

3 ADDITIONAL REQUIREMENTS 7

3.1 Chemical analysis 7

3.2 Mechanical properties 8

4 TESTING AND CERTIFICATION OF MATERIAL 9

4.1 General criteria for sampling 9

4.2 Test samples and specimens 9

4.3 Microstructure examination 11

4.4 Corrosion test procedure 12

4.5 Flaw assessment test 14

Note 1: It is the sum of all defects found on 7 tube welds at all levels 14

4.6 Certification 15

5 WELDING 16

6 ADDITIONAL TESTS ON MATERIALS 23

6.1 Workshop check of ferrite 23

6.2 Non Destructive Examinations 23

7 TESTS ON PRODUCTION WELDS AND CONSUMABLES 24

7.1 General 24

7.2 Tube to tubesheet weld production mock up 24

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ATTACHMENT 1 1 ATTACHMENT 2 1 ATTACHMENT 3 1 ATTACHMENT 4 1 ATTACHMENT 5 1 ATTACHMENT 6 1 ATTACHMENT 7 1 ATTACHMENT 8 1 ATTACHMENT 9 1 ATTACHMENT 10 1

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1 GENERAL

1.1 Scope and field of application

1.1.1 This specification covers the requirements for austenitic stainless steel materials and relevant welds in contact with the process fluid in the high pressure section of urea plants. These requirements shall be considered in addition to the ones of the codes and standards applicable to the product in question (equipment, piping components, plates, materials, testing, etc.). In case of conflict with any of the above standards, this document prevails.

1.1.2 This specification takes into consideration both the 316L UG stainless steel (UNS S31603) and the 25Cr-22Ni-2Mo type stainless alloy (UNS S31050).

1.2 Definitions

Owner: The company that has placed the order to suppliers as permitted under the license granted by Snamprogetti.

Supplier: Before placing the order it means each of the potential supplier(s) contacted; after placing the order, it means the selected supplier(s).

Snamprogetti: Snamprogetti S.p.A., the licensor of the urea process.

316L UG: “urea grade modified” 316L type austenitic stainless steel that shall meet all the requirements of the AISI 316L (UNS S31603) material specification and all the additional requirements mentioned in this specification.

“sample” the piece of semifinished/ finished product (tube, plate, W.O., etc.) from which the specimens to be tested are taken out

“specimen” a piece of material obtained from the sample and actually subjected to the destructive tests described below (corrosion test, metallography, etc.).

1.3 Abbreviations

AISI American Iron and Steel Institute ASME The American Society of Mechanical Engineers ASTM American Society for Testing and Material AWS American Welding Society DIN Deutsches Institut fur Nürmung IIW International Institute of Welding UG Urea Grade alloy UNS Unified Numbering System W.O. Weld Overlay Deposit

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1.4 Referenced Codes (always latest revision)

ASME Sect. VIII Boiler and pressure vessel code - Pressure Vessel ASME Sect. IX Boiler and pressure vessel code - Welding and brazing

qualifications ASME Sect.V Non Destructive Examination ASME Sect. II Parts A & D Materials ASME Sect. II Part C Specification for welding rods, electrodes and filler metals EN 10204 Metallic materials – Types of inspection documents ASTM A262 Standard Practices for Detecting Susceptibility to Intergranular

Attack in Austenitic Stainless Steels ASTM E562 Standard Test Method for Determining Volume Fraction by

Systematic Manual Point Count AD MERKBLATTER Complete Technical Rules for Pressure Vessels (English Edition)

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2 MATERIALS

2.1 General

2.1.1 The list of suppliers and subvendors of plates, forgings, bars, piping and tubes for High Pressure Urea equipment and piping to be operated in contact with the urea process fluid shall be submitted to Snamprogetti for acceptance. For filler materials the provisions of chapter 5 shall be applied.

2.1.2 All semifinished products shall be supplied in the solution annealed condition. No heating over

400 °C shall be allowed during machining or any other manufacturing activity, except welding. If heating above 400 °C cannot be avoided, a new solution annealing heat treatment shall then be performed and new samples shall be taken and tested as described in chapter 4.

2.1.3 If, after solution annealing heat treatment, forgings or bars are submitted to machining and

more than 5 mm depth is removed from the side in contact with the process fluid, then a new solution annealing heat treatment is required except for the 25Cr-22Ni-2Mo alloy provided that the samples taken after machining satisfy the test requirements as per chapter 4.

2.1.4 All tubes and pipes shall be seamless type. Welded fittings are allowed provided that the requirements of chapter 5 are met.

2.1.5 Cast parts and rod bars are not permitted unless approved by Snamprogetti.

2.1.6 When 316L UG material is required, the use of 25Cr-22Ni-2Mo material is allowed as an alternative.

2.2 316L UG stainless steel (UNS S31603)

2.2.1 Stainless steel 316L UG type shall be in accordance with the ASME-(SA) specifications applicable to the relevant semifinished products; it shall also meet the additional requirements detailed in chapters 3 and 4.

2.3 25Cr-22Ni-2Mo alloy (UNS S31050)

2.3.1 Stainless steel 25Cr-22Ni-2Mo type shall be in accordance with the ASME-(SA) specifications applicable to the relevant semifinished products; it shall also meet the additional requirements detailed in chapters 3 and 4.

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3 ADDITIONAL REQUIREMENTS

3.1 Chemical analysis

In the following paragraphs the chemical or additional chemical requirements for 316 UG stainless steel and 25Cr-22Ni-2Mo alloy are reported. Any deviation from these requirements shall be subject to Snamprogetti’s acceptance.

3.1.1 316L UG stainless steel The 316L UG stainless steel base material shall have the following additional chemical

requirements: C = 0.020 % max. P = 0.015 % max. S = 0.010 % max. Ni > 13 % N = 0.10 % max. The carbon content restriction above does not apply to forgings provided no welding is

performed after the solution annealing heat treatment, not even for installation purposes.

3.1.2 25Cr-22Ni-2Mo stainless steel

The 25Cr-22Ni-2Mo stainless steel base material shall have the following chemical composition:

Cr = 24 ÷ 26 % C = 0.020 % max. Ni = 21 ÷ 23.5 % P = 0.020 % max. Mo = 2 ÷ 2.6 % S = 0.010 % max. Mn = 1.5 ÷ 2.0 % Si = 0.40 % max. N = 0.10 ÷ 0.15 % B = 0.0015 % max.

3.1.3 W.O. deposit shall meet the following requirements for a depth of at least 3 mm (see Attachment 8) from the “as welded” or machined surface:

Material type 316L UG:

C = 0.030 % max. (SAW-ESW-GTAW) C = 0.040 % max. (SMAW) Cr = 16.5 % min. Ni = 15 % min. Mo = 2.2 % min.

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Material type 25Cr-22Ni-2Mo:

C = 0.030 % max. (SAW-ESW-GTAW) C = 0.040 % max. (SMAW) Cr = 24 % min. Ni = 21 % min. Mo = 1.9 % min. and

20,1%5,0%30%

%5,1%% ≤++++=

MnCNi

SiMoCr

Ni

Cr

eq

eq

3.1.4 Chemical analysis at depth of 1 mm and 2 mm (see Attachment 8) shall also be performed and reported for information.

3.2 Mechanical properties

The mechanical properties of 25Cr-22Ni-2Mo stainless steel, at room temperature, shall be as follows:

Tensile strength 580 N/mm² min.

Yield strength (0,2% offset) 270 N/mm² min.

Elongation (l=5d) 30% min.

3.2.1 Short Time Tensile Test shall be performed/ certified at the design temperature (indicated on the Snamprogetti process data sheet) for each heat of Urea Stripper heat exchanger tubes.

3.2.2 If the design is carried out in accordance with ASME code BPVC section VIII, for forgings the code itself shall be applicable with reference to CODE CASE 2038.

3.2.3 For other requirements the relevant material/ product SA (ASME) specification shall be applied.

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4 TESTING AND CERTIFICATION OF MATERIAL

4.1 General criteria for sampling

Product Sampling for corrosion test Sampling for metallographic examination

PLATES One sample for each heat One sample for each plate

PIPING, FORGING One sample from each lot of no more than 50 pieces of each heat and same heat treatment

(1)

One sample from each lot of no more than 50 pieces of each heat and same heat treatment

(1)

BOLTS, NUTS, SMALL-SIZE FORGING

One sample for each heat

One sample from each lot even if of more than 50 pieces of each heat and same heat treatment

(1) for bolts, nuts, and

forgings of small size (Dia. ≤ 219,1 mm).

EXCHANGER TUBES One sample for each heat One sample from each lot of 200 pieces of each heat and same heat treatment

(1)

NOTE (1): definition of same heat treatment: - If final heat treatment is in a batch-type furnace = in the same furnace charge - If final heat treatment is in a continuos furnace = in the same furnace at the same

temperature, time at heat, and furnace speed.

4.2 Test samples and specimens

4.2.1 Samples for corrosion tests and microstructural examination shall be taken as per the above table (base material) and from each weld test during the welding procedure qualification. Overheating shall be avoided when cutting the specimens (thermal-cutting is not allowed). Each sample shall be marked, by stamping, with proper identification traceability number.

4.2.2 The area of each sample shall be of 180 cm2 as a minimum (if not otherwise specified in this

document) and shall permit to take out with sufficient allowance the following specimens: 1 for check (chemical) analysis 1 for corrosion test (see para. 4.4) 1 for corrosion re-testing (if required) 3 for microstructure examination (see para. 4.3) 1 for metallography re-testing (if required) 4.2.3 Each specimen shall include the side that will be in contact with the process fluid if known

(consequently liner plates shall then be installed by exposing to the process fluid the side that has been actually tested with positive results). Specimens for the corrosion test shall have an area of approximately 30 – 32 cm2, weight of 40 g minimum (100 g maximum) and, when feasible, an approximately rectangular shape with dimensions of about 50 x 25 x 5 mm.

4.2.4 In the case of plates with thickness over 7 mm, the specimen shall be reduced to 5 mm by

machining material in excess on the opposite side from that (those) in contact with the process fluid (avoiding overheating).

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4.2.5 In the case of tubes with outside diameter less than 30 mm, the sample shall have a cylindrical shape. In the case of tubes or pipes with outside diameter ≥ 30 mm, the sample shall be taken with length "a" approximately equal to arc "b" (see Attachment 5).

4.2.6 If the pipe or tube thickness is over 7 mm, the specimen thickness shall be reduced to 5 mm

by machining material in excess on the opposite side from that (those) in contact with the process fluid (avoiding overheating).

4.2.7 In the case of forgings or bars, if it is not possible to take a sample with the surface to be in contact with the process fluid, the sample shall be taken from the core of the forging bar. Test specimens shall be taken from the forging extension or by a representative specimen with the same heat and heat treatment having maximum treated thickness size of those forgings.

4.2.8 In the case of special pieces (valves, thermocouples, fittings, instrument separators, etc.) the supplier shall submit to Snamprogetti for acceptance an overall drawing showing the location of the sample(s).

4.2.9 In the case of welding procedure qualification tests for SAW/ ESW/ SMAW weld overlay (see Attachment 1) three samples shall be taken: - sample S1 (Attachment 2) which shall include at least 2 bead overlap of adjacent beads - sample S2 (Attachment 3) which shall include stop and restart point of a bead - sample S3 (Attachment 4) which shall include beads deposited by manual welding with

SMAW and/ or GTAW on the automatic overlay, simulating repair if any.

4.2.10 The specimens obtained from each of the above samples shall be used as follows:

- specimen(s) labeled ‘A’ are to be used for metallographic analysis (one is for re-testing if required)

- specimen(s) labeled ‘B’ are to be used for corrosion test - specimen labeled ‘B1’ is to be used for corrosion re-testing if required - specimen labeled ‘C’ is to be used for macrographic examination - specimen labeled ‘D’ is for chemical check analysis.

4.2.11 In the case of welding procedure qualification tests for additional automatic GTAW weld overlay on liner plates or SAW/ ESW/ SMAW weld overlay, a sample of S1 type including at least 2 bead overlap of adjacent beads (see Attachment 2) shall be taken out.

4.2.12 In the case of welding procedure qualification test for butt joints, the sample shall be as wide as the face of weld in contact with the process fluid plus 12 mm (6 mm each side) and 5 mm thick (see Attachment 6).

4.2.13 In the case of procedure qualification tests for welds between tube and tube-sheet, no. 2 mock-up shall be prepared. From the first one the specimens for corrosion test and metallographic examination shall be obtained and they shall include 3 tubes in central position. One central tube shall be used for the corrosion test, one shall be used for the metallographic examination, one is for re-testing, if required (see Attachment 7 for details). The second mock-

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up shall be prepared following Attachment 9 and it will be subject only to the flaw assessment test as detailed in para 4.5.

4.2.14 The metallographic examination of the first mock-up shall be performed on the central tube assembly previously longitudinally sectioned following 4 perpendicular directions starting from the second weld pass stop as follows:

a) on 4 of the 8 surfaces obtained from the sectioning a macrographic examination shall be performed in order to determine the extension of weld fusion (which shall not exceed at any point 75 % of wall tube thickness), weld throat thickness (minimum weld throats of all sections shall be not less than the specified tube wall thickness) and penetration.

b) the 4 remaining surfaces shall be used for the microstructural examination (one surface for each of the 3 required etchings plus one for re-testing if required).

4.2.15 The surface to be in contact with the process fluid and the opposite one if not machined shall remain in the "as received" condition.

4.2.16 The specimens shall not be subjected to any heat treatment before the test.

4.2.17 The remaining part of each sample after taking out the specimens, with the identification number, shall be made available for five years (ex work delivery) at Supplier’s care for further Samprogetti investigation.

4.2.18 All tests described below (macrographic and micrographic examination, corrosion test, flaw assessment, etc.) shall be performed and certified by a laboratory approved by Snamprogetti. Laboratory shall officially inform Snamprogetti about any inconvenience (e.g. deviations from the material requirements etc.) encountered during the tests as well as in case of re-testing.

4.3 Microstructure examination

4.3.1 The material (base, welds and weld overlay) used in contact with the process fluid shall be

subject to metallographic analysis following the methods detailed below. 3 (three) metallographic specimens, each for any required etching, shall be obtained from each of the sample(s) as detailed in para. 4.2.2 and 4.2.10. A fourth specimen shall be retained for re-testing (if required). The re-use of the same metallographic specimen for two or more different etchings is not allowed.

4.3.2 The metallography shall be considered preliminary to the corrosion test.

4.3.3 Presence of ferrite shall be evaluated by means of a ferritometer on each of the 3 specimens before etching. Ferrite content shall not be greater than 0.6 % in all specimens except for SMAW welds for which 1% is allowed.

4.3.4 The material microstructure shall be determined following ASTM A262 Practice A. Only a fully austenitic step structure as defined in the above standard shall be considered acceptable. The presence of any structure other than the step structure (e.g. ditch structure, interdendritic ditches, end-grain pitting type I or II) is not allowed.

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4.3.5 Presence of sigma phase shall be checked at 100x and 500x after electrolitic etching with NaOH 10N at 3 V and 0.5 to 1 A/cm2 for 2 to 5 sec. Sigma phase shall be absent.

4.3.6 An etching with oxalic acid (10%, 6 V DC, 0.5 – 1 A/cm2, 15 sec.) shall be performed and the specimen shall be examined at 100x and 500x. Presence of any intergranular or intragranular compounds or phases other than the austenitic phase is not allowed whatever their composition might be and irrespective of their quantity, with the exception of the ferrite phase within the limits stated in para. 4.3.3.

4.3.7 The material not in compliance with the above requirements shall be rejected.

4.4 Corrosion test procedure

4.4.1 The corrosion test, Huey type, shall be performed on the sample material that already resulted acceptable after the microstructure examination detailed in para 4.3.

4.4.2 AISI 316L UG specimens shall be subjected to 5 test periods and the acid shall be renewed each time. Each period shall last 48 hours actual boiling. 25Cr-22Ni-2Mo alloy shall be subjected to 10 test periods at the same conditions as above.

4.4.3 The corrosion test shall shall follow the ASTM A262 Practice C with the following additions:

4.4.4 Only one specimen shall be tested in each flask.

4.4.5 A finger type refrigerator shall be used and it is necessary to check, by litmus paper, that no acid vapours are released during testing.

4.4.6 The ratio of the solution volume to the sample area shall be 20 ml/cm² as a minimum.

4.4.7 The flasks for Huey test shall be used only for this purpose. 4.4.8 The flask, refrigerator and specimen shall be carefully rinsed after each test cycle to remove all

the corrosion products (by means of a nonmetallic brush). 4.4.9 Before corrosion testing, the specimens shall be first degreased in acetone (chlorinated agents

are not allowed), pickled in boiling nitric acid (65%) for thirty minutes, and then rinsed; the corrosion products shall be removed by nonmetallic brush.

4.4.10 After each test cycle and after rinsing, the specimens shall be dipped in acetone, dried by hot

air, and weighed (when cold). 4.4.11 The time between two cycles shall be as short as possible.

4.4.12 Besides the determination of the corrosion rate (for each cycle and for the overall periods) obtained by weighting, it is also required to determine the maximum depth of attack by examining under a microscope the edges of a specimen section (for details see note 5 of table in para. 4.4.13)

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4.4.13 The following table shows both the maximum corrosion rate and depht of attack allowed in each test cycle and for the average of the results of all cycles, calculated according to ASTM A262 Practice C:

Semifinished

product

Type of material

Corrosion

rate (mm/month)

Depth of

attack (micron)

Plates, sheets,

bars, tubes, pipes,

forgings

316L UG

25Cr-22Ni-2Mo

0.025 (1) (2)

0.015 (1) (2)

90 (4) (5)

70 (4) (5)

Welds and

W.O. surfacing

316L UG

25Cr-22Ni-2Mo

0.025 (1) (3) (4)

0.015 (1) (3) (4)

90 (3) (4) (5)

70 (3) (4) (5)

NOTES General: the above limits are valid for each test cycle and for the average

of the results of all cycles.

(1) If the corrosion rate exceeds the rate specified in the table or if the corrosion rate in cycle 5 (cycle 10 for 25Cr-22Ni-2Mo alloy) exceeds the one in cycle 4 (cycle 9 for 25Cr-22Ni-2Mo alloy) by more than 50%, a second specimen taken from the same sample under examination shall be re-tested with the same procedure. Only the result of re-testing shall be taken into consideration. Further re-testings are not allowed.

(2) No deviations allowed.

(3) The heat affected zone and the bead overlap zone (for W.O.) shall also

be examined.

(4) Any deviation shall be subject to Snamprogetti’s acceptance.

(5) Depht of attack shall be determined after completion of the corrosion test by taking a metallographic sample from the most corroded area, if visible. The value shall be reffered to the deepest attack observed on both the transverse and the longitudinal directions of the specimen.

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4.5 Flaw assessment test

4.5.1 Samples to be tested shall be prepared in accordance with Attachment 9 (Procedure

Qualification Record) and Attachment 10 (production mock-up).

4.5.2 The tube protusion shall be machined down until the contact between tube face and the upper weld toe. This surface shall be recorded as starting test level. The examination shall proceed on repeated plane at 1 mm distance from each other till the tube gets lose.

4.5.3 Each level shall be prepared for etching and examined under a binocular microscope with magnification from x15 to x25.

4.5.4 The following table gives the number and extension of the allowable defects:

Defect type Max. allowed number of

defects (1) Max. dimensions allowed

Cracks (2) 0 - Pores 5 0.6 Wormholes 0 - Slag inclusions 2 0.6 Fusion defects 2 2 Crater cracks 0 - Burn through 0 -

Note 1: It is the sum of all defects found on 7 tube welds at all levels Note 2: Any deviation shall be subject to Snamprogetti’s acceptance

4.5.5 The weld fusion depht shall have a regular profile and its extension shall never exceed the 75

% of the wall tube thickness at any point

4.5.6 No more than 1 defect per tube and per level is allowed. Any deviation shall be subject to Snamprogetti’s acceptance.

4.5.7 Defects extended on different levels are not allowed.

4.5.8 A photograph shall be taken on each surface (scale 1:1) showing defects location, type and extension.

4.5.9 Certification of the flaw assessment test shall be in accordance with para. 4.6.

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4.6 Certification

4.6.1 The laboratory shall certify that the test results are in compliance or not in compliance with the requirements of the present specification. The certification shall be made available to Snamprogetti as soon as the certificate is issued. Certification shall include the following:

4.6.2 A photograph(s) showing the samples as received; the identification stamping on the sample(s) shall be clearly visibile and readable.

4.6.3 The photomicrographs showing the material’s microstructure after each etching. The photos shall be of high quality and fully readable (e.g. laser prints on photographic quality paper, prints from photo negatives etc.). B/W or color photocopies are not acceptable.

4.6.4 The etching details, the magnifications employed and a short but comprehensive comment by a metallurgy specialist shall be reported in each caption. The result of the ferrite check on each specimen shall also be reported.

4.6.5 The corrosion rates after each testing cycle and the average corrosion rate values shall be reported.

4.6.6 As an option the testing certificate can be supplied in electronic (PDF) format provided the above requirements are fully met.

4.6.7 Snamprogetti reserves the right to require to the Supplier (or the Owner) further testing or investigation whenever Snamprogetti’s acceptance is required or the laboratory results are controversial.

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5 WELDING

5.1 Weldings and weld overlays shall be performed with special filler materials, low ferrite type, approved by Snamprogetti. The approved filler materials for both 316L UG and 25Cr-22Ni-2Mo alloys are listed below. Different filler materials or wire/strip–flux combination shall not be used unless approved by Snamprogetti.

316L UG

CLASS 25Cr-22Ni-2Mo

Electrodes •(Avesta) P6 •(Thyssen) Thermanit 19/15 H •(Kobe Steel) NC 316 MF •(ESAB) 316 KCR •(Siderotermica) CITOXID B 316 LM

•(VEW) FOX EASN 25 M •(Thyssen) Thermanit 25 / 22 H •(Soudometal) Soudinox LF •(Kobe Steel) NC 310 MF •(Esab) FILARC BM 310 Mo L

Wires •(Thyssen) Thermanit 19/15 H •(Kobe Steel) no. 4051 •(Siderotermica) Siderfil 316 LM

•(Thyssen) Thermanit 25/22 H •(Kobe Steel) TGS 310 MF •(Sandvik) 25-22-2 L Mn •(VEW) FOX EASN 25 MIG

Strips •(Sandvik) 20-16-3 L Mn with (Soudometal) 12 b 316 LFT 2 flux •(Thyssen) 21.17.E with (Soudometal) Rekord 13 BLFT flux

•(Sandvik) 25-22-2 L Mn with (Soudometal) Rekord 13 BLFT flux or with (Sandvik) 31S flux •(Sandvik) 25-22-2 L Mn with (Sandvik) 37 S flux (electroslag) •(Thyssen) 25-22 H with (Soudometal) EST 122 flux (electroslag)

General note: the materials of class 25Cr-22Ni-2Mo can be used for welding of materials of class 316L UG.

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5.2 WPS/PQR applicable codes and additional required tests are summarized in the following table:

Weld Overlay Specimen

Sample S1 Sample

S2

Sample

S3

Butt joints Tube to

tubesheet joints

Applicable code (1) - ASME IX ASME IX ASME VIII Div. 2

Art. F3

Corrosion test B YES (para. 4.4) NO NO YES (para. 4.4) YES (para. 4.4)

Chemical analysis D YES (para. 3.1.3 and 3.1.4) NO NO

Microstructure examination A YES (para. 4.3) YES (para. 4.3) YES (para. 4.3)

Macroexamination C YES (2) NO NO YES (3) YES (para. 4.2.13)

Flaw test E NO NO YES (para. 4.5)

NOTES: (1) Unless otherwise specified in the design code indicated in the purchase order.

(2) For W.O. the macroexamination shall be performed only on sample S1. The purpose of macroetching is to identify the sequence of the weld beads overlay and the location of the heat affected region of each weld pass, due to the re-heating during the application of the subsequent pass. Specimen ‘B’ shall be taken out by the laboratory across the centerline of the above mentioned area (see Attachment 2).

(3) Macroexamination to be performed to check weld structure, presence of slag porosity and cracks in weld and heat affected zone.

5.3 PQR shall include the certification detailed in para. 4.6.

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5.4 In addition to the provisions of the applicable codes the validity of the PQR is five years from

issue date and the following essential variables, if modified from what qualified during the Procedure Qualification Record as indicated in the following tables, require the welding qualification tests to be repeated:

PRESSURE/ NOT PRESSURE RETAINING WELDS

BUTT AND FILLET WELD

ACCEPTED WELDING PROCESSES VARIABLES

Shielded Metal Arc Welding Gas Tungsten Arc Welding

Heat input Heat input or volume of the weld metal increased more than 10%

Interpass An increase of interpass temperature

Welding position A change in the welding position (a PQR done in 3G-5G-6G-vertical-uphill progression qualify all other position except vertical-down progression)

Filler metal size A change in filler metal size

Filler metals A change in the type, manufacturer of filler metal and/or trade name

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CORROSION RESISTANT WELD OVERLAY

ACCEPTED WELDING PROCESS

VARIABLES Submerged Arc Welding

Electroslag welding

Gas Tungsten Arc

Welding

Shielded metal arc welding

Base Metal A change in the P or Gr number

Base Metal thickness A change of ±30 % in the base metal thickness

Welding current intensity

A change of ±10% A change of ±5%

A change of ±10%

Not required

Current density (A/mm2) (strip welding)

A change of ±10% A change of ±5%

Not required

Arc voltage A change of ±10% Not required

Welding speed A change of ±5% Not Required

Heat input An increase of heat input more than what qualified Heat input or volume of the weld metal

increase more than 5%

Stick-out A change ±2.5% of the strip/wire stick-out with respect to PQR

A change ±2.5% of the strip/wire stick-out with respect to PQR (for machine/ automatic process)

Not applicable

Preheat and interpass A change in the preheat±25°C (first layer) and/or an increase of interpass temperature (all layers)

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Sheet 20 (24)


CORROSION RESISTANT WELD OVERLAY

ACCEPTED WELDING PROCESS

VARIABLES Submerged Arc

Welding Electroslag

welding Gas Tungsten Arc Welding

Shielded metal arc welding

PWHT (on first layer) A change in the temperature (±15°C)

Bead overlap A change +20%/ -0% of the overlap of adjacent beads with respect to that

measured on PQR (applicable to first and last layers)

A change +20%/ -0% of the overlap of adjacent beads with respect to that measured on PQR (applicable to first and last layers (for

machine/ automatic process)

N/A

Bead width A change +20%/ -0% of the bead width with respect to that measured on PQR

(applicable to first and last layers)

A change +20%/ -0% of the bead

width with respect to that measured

on PQR (applicable to first and last layers (for

machine/ automatic process)

N/A

Welding position A change in the welding position

Filler metal size and/ or thickness

A change in filler metal size and/or thickness

Layer thickness (to be specified in WPS/ PQR)

An increase in layer thickness (applicable to each layer)

Number of weld layers A decrease in the number of weld layers with respect to PQR

Filler metals A change in the type, manufacturer and/or trade name

Flux A change in the type, manufacturer and/or trade name

Not applicable

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Sheet 21 (24)


TUBE TO TUBESHEET WELDING

ACCEPTED WELDING PROCESS VARIABLES

Orbital Gas Tungsten Arc Welding

Manufacturer, type/ model of welding machine

A change of manufacturer, type/model of welding machine to another.

Welding program (supplementary document to be attached to the WPS)

A change in any data included in the supplementary document specifying all applicable equipment settings (pre-gas/post-gas/welding parameter for each sector/etc.) to assure a consistent performance.

Base Metal: Tubesheet (solid, W.O. or clad), Tube (internal or external)

A change in the base metal type, grade or product form

Tubesheet (solid pressure containment parts)

A change of ±30% in the tubesheet (solid pressure containment parts) metal thickness

Tubesheet (W.O., clad) A decrease in the layer number and/or increase of layer thickness.

Shielding/Backing(inside tube gas)/Trailing gas

A change/deletion in the gas composition and flow rate used

Tubes A change in the manufacturer, wall thickness or diameter

Tube holes A change in the pitch

Clearance between tubes and tube holes

The clearance between the outside surface of the tubes and the inside surfaces of the tube holes shall not exceed clearance used in the welding qualification tests

Positioning system A change in the positioning/centering system of the weld head on the tube sheet

Non fusible electrodes A change in the type, size, tips shape/angle, protrusion from the torch

Welding position A change in the welding position

Filler metal size A change in filler metal size

Tubes protrusion A change in the tube protrusion form tubesheet

Filler metals A change in the type, manufacturer and/or trade name

Interpass An increase of interpass temperature

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Sheet 22 (24)


5.5 The root pass on pipe butt joints shall be carried out by argon gas welding and with backing gas inside the pipe.

5.6 Weld overlays shall be performed with at least two layers in the case of automatic process, (except strip weld overlay on liner plates) and at least three layers in the case of manual welding: in any case, at least two layers shall be performed with low ferrite filler in compliance with para. 5.1.

5.7 Stress relieving heat treatment shall be carried out after first barrier layer before to start with the further corrosion resistant layer.

5.8 The weld face in contact with the process fluid shall be adequately smooth, free from undercuts or defects.

5.9 No grinding will be allowed, except on tube sheets or for removing local defects or discontinuities.

5.10 Care shall be taken during fabrication to avoid iron contamination of the austenitic surfaces by tools (grinding wheels, brushes, clamps, etc.).

5.11 The grinding wheels must not have been previously used on ferritic steels and the brushes must have austenitic stainless steel wires.

5.12 Weld overlay deposit on 25Cr-22Ni-2Mo liner plates shall be performed by providing a forced back water cooling circulation system during weld operations in order to keep interpass temperatures lower than 50°C. Automatic interpass temperature control shall be adopted.

5.13 Electrodes for manual welding or weld overlay shall have a diameter not greater than 4 mm (preferably 3.25 mm max.) and, where possible, shall be used with stringer bead technique.

5.14 All the welds of internal parts to the lining shall be performed by full-penetration welding procedure.

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Sheet 23 (24)


6 ADDITIONAL TESTS ON MATERIALS

6.1 Workshop check of ferrite

In addition to the requirements of para 4.3.3 the ferrite content shall also be checked in the workshop by magnetic permeability measurement by means of appropriate portable equipment previously calibrated and certified per AWS A4.2. An annual calibration certification shall be available to the Snamprogetti inspector. Prior to use in production, instrument calibration shall be verified with IIW secondary weld metal standards (0 - 15 % ferrite range). This check shall be carried out on each plate or forging and on at least one every 50 pipes or tubes from the same heat and heat treatment and on one bolt and one nut for every lot and every size from the same heat and heat treatment (for definition of “same heat treatment see Note 1 in para. 4.1).

6.2 Non Destructive Examinations

6.2.1 The tubes for heat exchangers shall be 100% tested with ultrasonics and eddy currents in accordance with ASTM A 450.

6.2.2 For eddy current test the calibration tube shall contain all the following discontinuities to establish the minimum degree of sensitivity for rejection of tubes:

- a longitudinal notch on a radial plane parallel to the tube axis on the outside surface, having a length of 6.35 mm, maximum width 0.8 mm, and depth 10% of the tube thickness but not less than 0.1 mm.

- a circumferential notch on a transverse plane to the longitudinal axis of the tube, having a depth of 10% of the tube thickness but not less than 0.1 mm.

- Three or more through holes, equally spaced circumferentially around the tube and longitudinally separated by a sufficient distance to allow distinct identification of the signal from each hole. The diameter of hole shall not be larger than 0.8 mm.

6.2.3 For ultrasonic examination, the calibration tube shall contain all the following discontinuities to establish the minimum degree of sensitivity for rejection of tubes:

- a longitudinal notch on a radial plane parallel to the tube centre line, having a depth 5% of the tube thickness but not less than 0.1 mm; on both the outside and inside surface

- a transverse notch, tangent to the surface and perpendicular to the longitudinal centre line of the tube, having a depth 5% of the tube thickness but not less than 0.1 mm., on both the outside and inside surface

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Sheet 24 (24)


7 TESTS ON PRODUCTION WELDS AND CONSUMABLES

7.1 General

7.1.1 Welding consumables (electrodes, wires, rods, strips and fluxes) shall be certified for the

different heats/lots according to EN 10204 type 3.1.B. Snamprogetti and the owner reserves the right to request a chemical check analysis on production welds.

7.1.2 Butt welds shall be fully radiographed (if physically feasible).

7.1.3 All welds and weld overlay deposit top layer shall be examined by dye penetrants, if possible on the side in contact with the process fluid or, if this is impracticable, on the outside.

7.1.4 After final machining (if any) the last tubesheet W.O. layer deposited shall have a minimum thickness of 3 mm. Along this thickness the chemical composition shall be in compliance with the requirements of para. 3.1.3. Supplier shall maintain full traceability of fulfiment of this requirement. Traceability data sheet shall be submitted to Snamprogetti inspector for review.

7.1.5 If the above requirement cannot be warranted by the supplier an additional weld overlay layer, other than that qualified on PQR, shall be deposited.

7.1.6 After machining of tubesheet weld overlay and before drilling operations a chemical sample shall be taken as per Attachment 8.

7.1.7 All the welds of internal parts to the lining shall be examined by dye penetrants after each welding pass.

7.2 Tube to tubesheet weld production mock up

7.2.1 Supplier shall provide no. 3 representatives production mock-up to verify the tube to tubesheet weld as per Attachment 9 and 10.

7.2.2 Mock-up shall be realised applying the same production tube sheet configuration, materials and welding parameters except for the carbon steel plate material on which the thickness should be reduced to a value equal at least the 30% of the original.

7.2.3 The frequency welding cycle verification shall be as follows:

a) No. 1 mock-up before starting any production welds b) No. 1 mock-up around middle production c) No. 1 mock-up before completion of the last 100 welds 7.2.4 On the mock-up 7.2.3 (a) an additional impediment shall be located in order to simulate the

peripheral tubesheet configuration (see Attachment 10).

7.2.5 Each tube samples shall have a minimum lenght of 100 mm.

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Sheet 25 (24)


7.2.6 Each tube weld sample shall be examined as per para 4.5.

Revision memorandum

Novembre 1984 Issue

August 1993 Rev. 01.

September 1995 Rev. 02.

Modified para 2.3.2 specifying the yeld strenght at 0,2% offset. Updated the list of approved filler

materials of table 3.5.1.a . Conversion in Word of the whole document.

September 2003 Rev. 03.

General revision

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ATTACHMENT 1

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ATTACHMENT 2

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ATTACHMENT 3

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ATTACHMENT 4

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ATTACHMENT 5

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ATTACHMENT 6

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ATTACHMENT 7

The arrows indicate the sectioning planes

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ATTACHMENT 8

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ATTACHMENT 9

Tubes To Tube Sheet Welds Qualification Procedure Test

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ATTACHMENT 10

Documents

spc cr ur 510 r03 e f L - National Fertilizers