5_Cargo Equipment and Instrumentation

7/26/2019 5_Cargo Equipment and Instrumentation

1/34

CARGO EQUIPMENT AND

INSTRUMENTATION


2/34

TANKS, PIPING AND VALVES

The loading lines and pipes mentioned hererefer to gas arrier!s argo handling s"stem#

This in$ol$es li%&id lines' $apo&r lines'

ondensate ret&rn lines' lines to $ent mast'pipes inside the argo tan( and sea)aterpipes to the argo ooling plant#

All loading lines on gas arrier* li%&id lines'

gas lines and lines to $ent mast ha$e thesame re%&irements as press&re $esselsregarding of temperat&re and press&re the"are meant to handle#


3/34

All loading lines o&tside the argo tan(m&st +e prod&ed +" material )ith meltingpoint no less than ,-#.oC# /oading lines

designed for argo )ith lo) temperat&re'less than 012oC m&st +e ins&lated from the ship h&ll# This to

pre$ent the ship h&ll to +e ooled do)n to

+elo) design temperat&re# To pre$ent oldargo spill on the h&ll plates' a drip tra"m&st +e plaed &nder the manifold 3anges#


4/34

On all argo lines )here it an +eli%&id it is re%&ired )ith safet" $al$e#4apo&r from the safet" $al$e o&tletm&st go +a( to the argo tan( or tothe $ent mast# If the ret&rn goes to$ent mast the pipe m&st +e e%&ipped

)ith a li%&id olletor to pre$entli%&id to the $ent mast# 4apo&r relief$al$es are also 5tted on the tan(

domes6 these relie$e to $ent sta(s#


5/34

Cargo valves

Isolating $al$es for gas arriers m&st +epro$ided in aordane )ith the IMOre%&irements# 7here argo tan(s ha$e a

MAR4S greater than 2#8 +arg 9T"pe C argotan(s:' all main and li%&id $apo&r onnetions9e;ept relief $al$e onnetions: sho&ldnormall" +e 5tted )ith a do&+le $al$e

arrangement omprising a man&all" operatedglo+e $al$e )ith a remotel" operatedisolation $al$e in series )ith this man&al$al$e#


6/34

Emergen" sh&t do)n 9ESD: is alsore%&ired to +e a&tomati &pon loss ofeletri or ontrol po)er' $al$eat&ator po)er or 5re at tan( domesor manifold )here f&si+le elementsare s&ita+l" sit&ated to at&ate the

ESD signal s"stem# ESD $al$es ma"+e either pne&matiall" orh"dra&liall" operated +&t in either

ase m&st +e


7/34

PRESSURE-RELIEF AND VACUUMPROTECTION SYSTEM

The IMO Codes re%&ire at least t)opress&re relief $al$es of e%&al apait" to+e 5tted to an" argo tan( of greater than

-2 M= apait"# >elo) this apait" one iss&?ient# The t"pes of $al$es normall"5tted are either spring@loaded or pilot@operated relief $al$es# Pilot@operated relief

$al$es ma" +e fo&nd on T"pes A' > and Ctan(s )hile spring@loaded relief $al$es are&s&all" onl" &sed on T"pe C tan(s#


8/34

PUMPS AND UNLOADINGSYSTEM

Cargo p&mps 5tted a+oardrefrigerated gas tan(ers are normall"of the entrif&gal t"pe' eitherdeep)ell or s&+merged' operatingalone or in series )ith a de(@mo&nted +ooster p&mp )here argo

heating is re%&ired on disharge topress&rise storage from arefrigerated $essel#


9/34

Ru!g "u#"s ! "arallel a$! ser!es

7hen gas arriers disharge' argo tan(p&mps are &s&all" r&n in parallel +&t )here arefrigerated ship disharges to press&rised

storage' argo tan( p&mps are r&n in series)ith +ooster p&mps# The argo 3o) ratesahie$ed +" an" p&mp or om+ination ofp&mps )ill depend &pon the +a(press&reeno&ntered d&e to stati head 9dierene inli%&id le$els of reei$ing tan( and tan( +eingdisharged: and the resistane to 3o) in theonneting pipeline#


10/34

Dee"%ell "u#"s

Deep)ell p&mps are the most ommont"pe of argo p&mp for /PG arriers# Thep&mp is operated eletriall" or

h"dra&liall" +" a motor' )hih is 3ange@mo&nted o&tside the tan(# The dri$eshaft is g&ided in ar+on +earings insidethe disharge t&+e and these +earingsare in t&rn l&+riated and ooled +" theargo 3o) &p the disharge t&+e#


11/34

The impeller assem+l" is mo&nted atthe +ottom of the argo tan( and )illfre%&entl" omprise t)o or three

impeller stages together )ith a 5rststage ind&er6 this latter is an a;ial3o) impeller &sed to minimise the

NPSB re%&irement of the p&mp#


12/34

Suerge$ "u#"s

This t"pe of p&mp is &sed on all /NG arriers'and on man" of the larger f&ll" refrigerated/PG arriers# The p&mp assem+l" and eletri

motor are lose o&pled and installed in the+ottom of the argo tan(6 po)er is s&pplied tothe p&mp motor thro&gh opper or stainlesssteel sheathed a+les' )hih pass thro&gh agastight seal in the tan( dome and terminatein a 3ameproof &ntion +o;# S&+mergedp&mps and their motors are ooled andl&+riated +" the argo #


13/34

'oos(er "u#"s

>ooster p&mps are also of theentrif&gal t"pe and ma" +e either$ertial in@line p&mps de(@mo&nted

in the appropriate disharge line anddri$en +" an


14/34

CARGO )EATERS AND CARGOVAPORI*ERS

A argo heater is &sed to heat the argo)hen disharging to an am+ient shoretan(# A argo heater is also &sed )hen

loading a f&ll" press&rised gas arrier )ithargo )ith temperat&re less than 012oC#Sea)ater or oil is &sed to heat the argoin the argo heater# It is of importane to

remem+er that the argo heater is f&ll of)ater and ha$e good 3o) o&t )ith )ater+efore letting old argo into the heater#


15/34

)ea( e+ager

Beat e;hangers are &tilised in se$eraldierent parts of argo handling on gasarriers' as heat e;hangers 9argo

heater:' ondensers for argo oolingplant' $apo&r risers' s&per heaters andoil oolers for ompressors# In most ofthe heat e;hangers sea)ater is &sed asthe medi&m on gas arriers' )hih theprod&ts are ooled or heated against#


16/34

Tu&e ea( e+agers

T&+e heat e;hangers are prod&ed)ith t&+e +&ndles either as straightenedpipes or &@formed pipes plaed into a

ham+er# The pipes in the t&+e +&ndle ha$ean inside diameter on 12 to -2 millimetres# Int&+e heat e;hangers' )here sea)ater is&sed as medi&m' the prod&t to +e heated

goes in the t&+e +&ndle# This pre$entsremaining sea)ater from freeing or pre$entsremnants of salt deposits inside the t&+es#


17/34

Pla(e ea( e+agers

Plate heat e;hangers are more &tilised in oldstorage plants on shore' for e;ample in the 5shind&str" and the meat ind&str"# Plate heate;hangers are +&ilt )ith thin plates )ith

do&+le li%&id hannels# The plates are installed)ith the 3at side to)ard eah other# The ooling

medi&m and prod&t are p&mped eah )a" inthe hannels to ahie$e the +est possi+le ooling

or heating# 7ater or oil is &sed as the oolingmedi&m and is dependent &pon the temperat&reof the prod&t that is to +e ooled or heated#


18/34

RELI.UEFACTION SYSTEMS ANDCONTROL OF 'OIL-OFF

This plant is spei5all" designed to perform thefollo)ing essential f&ntions*

91: To ool do)n the argo tan(s andassoiated pipe )or( +efore loading6

9-: To reli%&ef" the argo $apo&r generated +"3ash e$aporation' li%&id displaement and +oil@o d&ring loading )hen there is no $apo&rret&rn line to shore6

9=: To maintain or red&e argo temperat&reand press&re )ithin the presri+ed design limitsof the argo s"stem on passage#


19/34

There are t)o main t"pes ofli%&efation plant*

(a) Direct cycles- )here thee$aporated or displaed argo$apo&r is ompressed' ondensedand ret&rned to the tan(# This is the

most ommonl" &sed s"stem' +&tma" not +e emplo"ed for ertaingases#


20/34

(b) Indirect cycles- )here ane;ternal refrigeration s"stem isemplo"ed to ondense the argo

$apo&r )itho&t it +eing ompressed#This "le is relati$el" &nommon' asit re%&ires' for e?ien"' a $er" old

refrigerant and large s&rfaes#


21/34

CARGO COMPRESSORS

Compressors are &sed as $apo&rp&mps in all modern argo oolingplants' either to ompress or p&mp

argo $apo&r# Compressors are also&sed to ompress or p&mp oolingmedi&m as Freon $apo&r on

indiret argo ooling plant andasade plant# The ompressors inthe argo ooling plants are

prod&ed either as piston' sre) or


22/34

DIFFERENT TPES OFCOMPRESSORS

1# P!s(o o#"ressors -# Dou&le-a(!g o#"ressors

/0 S!gle-a(!g o#"ressors 10 Sre% o#"ressors

20 O!l 3ree sre% o#"ressors


23/34

INERT GAS SYSTEM

On gas arriers ier( gas is &sed for dierent p&rposes' someare re%&irements other is to maintain the ships h&ll and spaes*

H Ba$e ne&tral atmosphere in hold and inter +arrier spaes

H Elimination of argo $apo&r from the argo tan( )hengas freeing

H Eliminating o;"gen from the argo tan( +efore loading

H Dr"ing &p hold spaes or inter +arrier spaes to ahie$e a ne&tral atmosphere and to pre$ent orrosion in the spaes

H Plaing a ne&tral $apo&r a+o$e the argo if re%&ired


24/34

Inert gas generator has three mainparts# These are as follo)s*

A om+&stion ham+er )ithsr&++ing and ooling 9thegenerator:

A refrigerated drier @ ooled normall"+" R--' and

An a+sorption drier


25/34

INSTRUMENTATION

A ommonl" &sed de5nition of areasafet" lassi5ation for eletriale%&ipment in shore installations is as follo)s*

*oe 45 An area )ith a 3amma+le mi;t&reontin&o&sl" present# *oe 65 An area )here 3amma+le mi;t&res

are li(el" to o&r d&ring normal operations# *oe 75 An area )here 3amma+le mi;t&res

are &nli(el" to o&r d&ring normaloperations#


26/34

I(r!s!all8 sa3e 9!0s0:e;u!"#e(

Intrinsiall" safe e%&ipment isde5ned as an eletrial ir&it ofonneted apparat&s and )iring in

)hih no spar( or thermal eet&nder normal operation or spei5edfa&lt onditions is apa+le of a&sing

ignition of a gi$en e;plosi$e mi;t&re#


27/34

Fla#e"roo3 e;u!"#e(

A 3ameproof enlos&re is one )hihan )ithstand the press&rede$eloped d&ring an internal ignition

of a 3amma+le mi;t&re and )hosedesign is s&h that an" prod&ts ofthe e;plosion o&rring )ithin the

enlos&re )o&ld +e ooled +elo)ignition temperat&re +eforereahing the s&rro&nding

atmosphere#


28/34

Pressur!se$ or "urge$e;u!"#e(

This is a tehni%&e to ens&re that anenlos&re remains essentiall" gas@free either +" press&risation or +"

p&rging# In the ase ofpress&risation an o$erpress&re of 2#.m+ar relati$e to the s&rro&nding

atmosphere m&st +e maintained +"lea(age ompensation )hile in thease of p&rged enlos&re' a

ontin&o&s s&ppl" of p&rging gas


29/34

L!;u!$ level

>oth the IMO Codes and Classi5ationSoiet" R&les re%&ire e$er" argo tan( to+e 5tted )ith at least one li%&id le$el

ga&ge6 spei5 t"pes of ga&ging s"stemare re%&ired for ertain argoes as de5nedin Chapter JIJ of the IMO Code#

The IMO lassi5ation for ga&ging s"stems

is as follo)s*9a: I$!re( s8s(e#s@ )eighing or pipe

3o) meters#


30/34

9+: Close$ $ev!es)hih do not penetrate the argotan( 0 &ltrasoni de$ies or radioisotope so&res#

9: Close$ $ev!es)hih penetrate the argo tan( 03oat ga&ges' +&++le t&+e indiators' et#

9d: Res(r!(e$ $ev!es)hih penetrate the tan( +&t)hih release small $ol&mes of li%&id or $apo&r )henin &se' s&h as 5;ed or slip' t&+e ga&ges# 7hen not in&se' the restrited de$ie sho&ld +e (ept ompletel"losed#

The most ommon t"pes of le$el ga&ging onon$entional gas arriers are those desri+ed in 9:and 9d: a+o$e#


31/34

Dierent t"pes of Ga&gingS"stems

1# Floa( gauges 70 N!(roge &u&&ler gauges

/0 D!


32/34

Level alar# a$ au(o#a(!su($o% s8s(e#s

7ith the e;eption of T"pe C tan(s)hose apait" is less than -22 m='e$er" argo tan( m&st +e 5tted )ith

an independent high@le$el sensorgi$ing an a&di+le and $is&alalarm# Float' apaitane or

&ltrasoni sensors ma" +e &sed forthis p&rpose# This high le$el alarm orother independent sensor is re%&ired

a&tomatiall" to stop the 3o) of


33/34

Pressure a$ (e#"era(ure#o!(or!g

The IMO Codes all for press&remonitoring thro&gho&t the argo s"steminl&ding argo tan(s' p&mp disharge

lines' li%&id and $apo&r rosso$ers' et# The IMO Codes also re%&ire at least t)o

de$ies for indiating argo temperat&res'one plaed at the +ottom of the argo

tan( and the seond near the top of thetan(' +elo) the highest allo)a+le li%&idle$el#


34/34

Gas $e(e(!o s8s(e#s

The IMO Codes all for e$er" gas arrier to ha$e a 5;edgas detetion s"stem )ith a&di+le and $is&al alarmson the na$igating +ridges in the argo ontrol roomand at the gas detetor reado&t loation# Detetor headsm&st +e pro$ided in the follo)ing*

9a: Cargo ompressor room# 9&:Eletri motor rooms# 9: Cargo ontrol rooms &nless lassi5ed as gas@safe# 9$: Enlosed spaes s&h as hold spaes and inter+arrier

spaes e;epting hold spaes ontaining T"pe C argo

tan(s# 9e: Air lo(s# 93: 4ent hoods and gas to E#R# s&ppl" d&ts 9/NG ships:#

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5_Cargo Equipment and Instrumentation