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Txhawm rau kov yeej qhov qis- qhov kub thiab txias hauv LNG cov nroj tsuag, cov kws tsim khoom yuav tsum xaiv cov ntaub ntawv uas nws cov khoom siv hluav taws xob - mus rau - qhov kub thiab txias (DBTT) yog qhov qis dua qhov ua haujlwm kub ntawm -162 ° C. Cov pov thawj kev daws teeb meem yog 9% npib tsib xee steel (thawj lub tank), austenitic 6 L4 thiab 3 stainless hlau. piping), aluminium alloy 5083 (cov thawv txias thiab ISO ntim), thiab Invar membrane alloy rau nyias -membrane tanks. Txhua yam khoom yuav tsum raug cuam tshuam-kuaj ntawm nws qhov tsawg kawg nkaus tsim qhov kub thiab txias ntawm ASME lossis EN cov cai. |
Vim li cas qis -Tsub Brittleness Yog Qhov Kev Sib Tw ntawm LNG Nroj Tsuag
Liquefied Natural Gas yog khaws cia thiab thauj ntawm −162℃(−260℃F) - qhov kub ntawm methane ntawm atmospheric siab. Thaum qhov kub thiab txias no, ntau yam khoom siv hluav taws xob tau txais kev hloov pauv hauv kev coj tus cwj pwm: lawv hloov los ntawm ductile (khoov ua ntej tawg) mus rau nkig (shattering tsis ceeb toom). Qhov tshwm sim no, hu ua ductile - mus rau - kev hloov pauv hloov, yog ib qho ntawm cov kev ua tsis tau zoo tshaj plaws hauv kev tsim hluav taws xob cryogenic.
Qhov tshwm sim ntawm qhov ua tsis tiav hauv qhov chaw LNG yog qhov hnyav heev. Ib qho kev tso tawm tsis muaj peev xwm ntawm LNG tuaj yeem vaporize rau hauv huab cua uas muaj peev xwm tawg tau, lossis - yog ignited - hlawv li lub pas dej hluav taws uas nyuaj heev rau kev tua. Xyoo 1944 Cleveland LNG tank kev puas tsuaj, uas tshwm sim los ntawm lub tank ua los ntawm cov hlau tsis muaj nickel, tua 128 tus neeg thiab rhuav tshem tag nrho cov zej zog. Qhov xwm txheej ntawd tau tsim lub hauv paus hauv paus ntsiab lus tseem tswj hwm LNG cov khoom siv niaj hnub no: txoj cai alloy tsis yog xaiv tau.
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Ntsiab Lus Txhais:Lub Ductile-rau-Brittle Transition Temperature (DBTT) yog qhov kub hauv qab no uas cov khoom tawg sai sai yam tsis muaj qhov tseem ceeb ntawm cov yas deformation. Cov khoom siv tsuas yog muaj kev nyab xeeb rau cov kev pabcuam cryogenic yog tias nws DBTT zoo hauv qab qhov ntsuas kub tsawg kawg nkaus, tau lees paub los ntawm Charpy V-Notch (CVN) cuam tshuam kev kuaj. |
Lub Metallurgy Tom Qab Tsawg-Tsuas Kub Embrittlement
Cov hlau muab lawv cov tawv tawv los ntawm lub peev xwm ntawm atoms kom rov tsim kho (slip) raws cov dav hlau siv lead ua thaum muaj kev ntxhov siab. Ntawm qhov kub thiab txias, qhov no atomic mobility txo. Rau lub cev -centered cubic (BCC) hlau - nrog rau cov pa roj carbon steel thiab ferritic/martensitic stainless steels - plam yuav txwv tsis pub qis dua DBTT uas tawg sai dua cov hlau tuaj yeem nqus tau lub zog. Qhov tshwm sim yog tam sim ntawd, kev puas tsuaj puas tsuaj ntawm cov kev ntxhov siab zoo hauv qab cov khoom siv lub zog tensile.
Lub ntsej muag -centered cubic (FCC) hlau coj txawv txawv. Lawv cov qauv siv lead ua ua rau atomic plam txawm tias nyob rau hauv qhov kub thiab txias, yog li cov tawv tawv tau khaws cia rau qhov tsis muaj tseeb. Qhov no yog vim li cas austenitic stainless hlau (FCC) thiab txhuas alloys (FCC) yog thawj qhov kev xaiv rau LNG piping - lawv tsuas tsis muaj DBTT.
BCC hlau (carbon steel, ferritic SS):nthuav tawm lub ntse DBTT - txaus ntshai hauv kev pabcuam cryogenic tshwj tsis yog tshwj xeeb alloyed.
FCC hlau (304L / 316L SS, aluminium alloys):tsis muaj DBTT - tseem tawv ntawm −269℃. Thawj qhov kev xaiv rau LNG kav dej.
Siab -nickel ferritic alloys (9% Ni hlau):DBTT suppressed mus rau hauv qab −196℃los ntawm nickel ntxiv - engineering tov rau loj cia tso tsheb hlau luam.
Cov Khoom Siv Ua Haujlwm ntawm Cryogenic Kub: Cov ntaub ntawv sib piv
Cov lus hauv qab no nthuav tawm cov qauv qis -kub txhua yam khoom siv rau xya cov ntaub ntawv feem ntau tau teev tseg rau LNG cog kev pabcuam. Tag nrho cov nqi qis tshaj yog raws li ASTM lossis sib npaug EN cov qauv.
|
Khoom siv |
Min. Tsim Temp. |
CVN Toughness |
Elongation |
Daim ntawv thov tseem ceeb LNG |
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Carbon hlau (A516-70) |
-29 ° F (-20 ° F) |
27 J @ −29 degree |
21% |
Ambient cia tanks |
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3.5% Ni hlau (A203 Gr.E) |
-101 ° F (-150 ° F) |
27 J @ −101 degree |
21% |
Ethylene / propylene hlab ntsha |
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9% Ni hlau (A353 / A553) |
-196℃(-320℃F) |
34 J @ −196 degree |
20% |
LNG thawj tswj |
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304/304L SS (A312 TP304) |
-269℃(-452℃F) |
>100 J @ −196 degree |
40% |
Cryogenic piping & fittings |
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316L SS (A312 TP 316L) |
-269℃(-452℃F) |
>100 J @ −196 degree |
40% |
Cryogenic piping, twj tso kua mis |
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Invar (Fe-36Ni, F1684) |
-196℃(-320℃F) |
Zoo heev |
30% |
Membrane LNG tank systems |
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Aluminium alloy 5083 (B241) |
-196℃(-320℃F) |
Zoo |
16% |
LNG cia, ISO ntim |
Cov peev txheej: ASTM A353, A553, A312, A240, B241, F1684; ASME Tshooj VIII Div.1; TS EN 14620. CVN=Charpy V-Ntch cuam tshuam lub zog. Tag nrho cov txiaj ntsig yog cov lej tsawg kawg -xav tau cov lej; cov txiaj ntsig tau lees paub tseeb feem ntau yog siab dua.
Zone-los ntawm-Zone Material Selection Decision Guide
Ib tsob nroj LNG tsis yog ib puag ncig zoo ib puag ncig - nws spans qhov kub thiab txias gradient los ntawm ambient ntawm lub roj teeb txwv mus rau −162℃ntawm lub thawv txias thiab cov tso tsheb hlau luam. Cov cheeb tsam sib txawv xav tau cov khoom sib txawv. Kev siv cov khoom tsis raug hauv ib cheeb tsam - txawm luv luv - ua rau muaj kev pheej hmoo tawg tawg. Cov matrix hauv qab no yog koj thawj qhov siv rau thaj tsam -raws li kev xaiv.
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Thaj chaw cog |
Temp. Ntau yam |
Khoom siv pom zoo |
Ntsiab Specification Note |
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Pub Gas Inlet / Slug Catcher |
0℃rau -20 degree |
Carbon Steel A333 Gr.6 |
ASME B31.3; txwv PWHT yuav tsum tau |
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Ua ntej-Coling Section (MR) |
-20℃rau -80 degree |
3.5% Ni Steel los yog 304L SS |
Impact tested per ASME VIII Div.1 UHA |
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Liquefaction Txias Box |
-80℃rau -165 degree |
304L / 316L SS; ib 5083 |
Tag nrho CVN xeem @ min. tsim temp. |
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LNG Cia Tank (sab hauv) |
-162 ° F (-260 ° F) |
9% Ni Steel los yog Invar membrane |
EN 14620 / API 625; 100% RT ntawm seams |
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LNG Cia Tank (sab nraud) |
Ambient |
Pre-Stressed Concrete lossis CS |
Thermal barrier ntawm lub plhaub |
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LNG Pump & Piping (hauv -tank) |
-162 degree |
304L / 316L SS; ib 5083 |
ASTM A182 F304L flanges; qis-temp bolting |
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BOG Compressor Suction |
-100℃rau -162 degree |
304L SS lossis Al 6061-T6 |
Tsis yog- sib nqus, qis- ntsuas kub |
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LNG Loading Arms |
-162 degree |
316L SS nrog Al lossis 9% Ni fittings |
API 1540; cryogenic swivel pob qij txha |
PWHT=Tshaj tawm -Kev kho cua sov. HAZ=Thaum tshav kub kub-Teb chaws cuam tshuam. BOG=Boil-Tawm Gas. RT=Kev ntsuas hluav taws xob. Specifications yog qhia; ib txwm txheeb xyuas tawm tsam qhov project-cov lej tsim tshwj xeeb thiab tus tswv engineering qauv.
Peb Pillars ntawm Cryogenic Khoom Xaiv
Tsis muaj cov khoom siv cryogenic ua tiav yam tsis muaj Charpy V-Notch (CVN) cuam tshuam kev ntsuas ntawm lossis qis dua qhov ntsuas kub tsim nyog. CVN kuaj ntsuas lub zog ib tus qauv notched specimen absorbs ua ntej fracturing - ib tug ncaj qha taw qhia ntawm toughness ntawm qhov kub ntawd. Rau cov pa roj carbon thiab qis- alloy steels, qhov tsawg kawg nkaus xav tau lub zog yog feem ntau 27 Joules (20 ft-lb). Rau austenitic stainless hlau, qhov tseem ceeb tshaj 100 J ntawm −196℃yog ib txwm ua tiav. Tsis txhob txais cov ntaub ntawv tsis muaj cua sov-cov ntawv pov thawj CVN tshwj xeeb.
Toughness yog rhiab heev rau kab chemistry. Sulfur thiab phosphorus impurities embrittle ferritic steels ntawm qhov kub thiab txias. Rau 9% Ni hlau, cov ntsiab lus nitrogen yuav tsum tau tswj qis dua 0.01% txhawm rau tiv thaiv kev mob - hnub nyoog embrittlement thaum lub sij hawm tsim. Rau austenitic stainless hlau, carbon yuav tsum raug txwv rau 0.03% siab tshaj (tus "L" qib) los tiv thaiv rhiab heev thaum vuam. Kev txheeb xyuas cov khoom zoo (PMI) - siv X-ray fluorescence (XRF) lossis optical emission spectroscopy - yuav tsum tau ua ntawm 100% ntawm cov khoom siv hlau ua ntej kev teeb tsa kom paub tseeb tias tsis muaj qib qis dua - cov khoom siv tau hloov pauv.
Welds yog qhov chaw yooj yim tshaj plaws nyob rau hauv txhua qhov system siab, thiab ob npaug ntawm qhov kub thiab txias. Thaum tshav kub kub- thaj tsam cuam tshuam (HAZ) ntawm lub vuam ua rau lub voj voog nrawm nrawm uas tuaj yeem hloov pauv cov qauv nplej thiab txo cov tawv nqaij. Txhua qhov txheej txheem weld specification (WPS) rau cov kev pabcuam cryogenic yuav tsum suav nrog cov txheej txheem kev tsim nyog cov ntaub ntawv (PQRs) nrog CVN kuaj ntawm vuam hlau thiab HAZ ntawm qhov tsawg kawg nkaus tsim kub. Rau 9% Ni hlau, cov hlau muab tub lim feem ntau yog npib tsib xee- alloy raws li (ENiCrMo-6 lossis ENiCrFe-9) es tsis yog qhov sib xyaw ua ke, tshwj xeeb vim tias cov khoom siv nickel khaws cov tawv nqaij thoob plaws tag nrho cov khoom siv cryogenic.
Yam yuav tsum tau muaj kev xeem: Ntawm ib sab
Cov lus hauv qab no suav nrog cov kev ntsuam xyuas tseem ceeb, cov qauv siv tau, thiab cov qauv kev lees paub uas tswj hwm cov khoom tsim nyog rau LNG cog kev pabcuam.
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Hom kev xeem |
Txuj |
Thaum siv |
Kev lees txais |
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Charpy V-Notch (CVN) |
ASTM E23 / EN ISO 148 |
Yam tsawg kawg nkaus tsim kub |
Txais: Ntau dua lossis sib npaug rau 27 J (ferritic); Ntau dua lossis sib npaug rau 100 J (austenitic) |
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Tee-Qhov hnyav Tear Test |
ASTM E 436 1 |
9% Ni thiab qis- alloy steels |
100% shear tawg zoo li |
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Tensile (Tsawg-Temp) |
ASTM A 370 Cov Lus Qhia Tshwj Xeeb |
Ntawm -196℃rau qib cryogenic |
UTS thiab yield yuav tsum tau raws li min. @test temp. |
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Hardness (Vickers/Brinell) |
ASTM E92 / E10 |
Weld HAZ; post-PWHT |
HV 10 max 350 rau BS PD 5500 |
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Kev ntsuas hluav taws xob (RT) |
ASTM E94 / EN ISO 17636 Daim Ntawv Pov Thawj |
Tag nrho cov - nkag mus rau hauv qab welds |
Kev lees txais rau ASME B31.3 lossis EN 13480 |
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Ultrasonic (UT) |
ASTM E 164 |
Phaj thiab hnyav phab ntsa fittings |
Phased -array UT nyiam rau cov ntu tuab |
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Kua Penetrant (PT) |
ASTM E165 |
Austenitic SS kawg nto |
Tshawb xyuas cov kab nrib pleb; ntxuav nrog acetone |
|
Positive Material ID (PMI) |
ASTM E1476 (XRF) |
Tag nrho cov alloys ntawm lub installation |
Txheeb xyuas Ni, Cr, Mo cov ntsiab lus; 100% kev soj ntsuam |
Cov qauv siv yog tam sim no ASTM / EN / ASME edition. Qhov project-kev tshuaj xyuas tshwj xeeb thiab cov phiaj xwm sim (ITPs) tuaj yeem tsim cov cai nruj dua. Ib txwm sib haum nrog cov qauv tsim qauv - feem ntau ASME B31.3 rau cov txheej txheem piping, API 625 / EN 14620 rau cov tso tsheb hlau luam.
Tsib Qhov Kev Xaiv Cov Khoom Uas Tsis Txaus Siab - thiab Yuav Ua Li Cas Zam Lawv
yuam kev 1:Siv cov pa roj carbon steel hauv qab -29℃yam tsis muaj kev cuam tshuam.
Txheem carbon steel (A106 Gr.B) tsis cuam tshuam - kuaj thiab muaj DBTT tsis tuaj yeem. Ib txwm siv A333 Gr.6 (kev cuam tshuam- kuaj rau −46 degree) lossis cryogenic- qib hloov rau qhov kub hauv qab −29℃. Txawm tias kev mus ncig ib ntus hauv qab qhov pib no - thaum lub caij cog qoob loo, piv txwv li - tuaj yeem pib tawg tawg.
yuam kev 2:Piv txwv tias 304 SS thiab 304L SS yog sib hloov.
Hauv kev pabcuam cryogenic, qhov kev xaiv 'L' tseem ceeb. Standard 304 (max 0.08% C) txaus ntshai rhiab heev ntawm weld HAZ, tsim chromium-depleted aav susceptible to intergranular corrosion nyob rau hauv kab ya raws. Ib txwm qhia 304L lossis 316L rau welded cryogenic piping.
yuam kev 3:Hla PMI ntawm 'certified' cov ntaub ntawv los ntawm warehouse.
Sib tov-ups ntawm cov qib alloy hauv lub tsev rau khoom lossis cov khw muag khoom yog cov ntaub ntawv ua rau kev ua tsis tiav cryogenic. Ib daim ntawm carbon steel yeeb nkab misidentified li 9% Ni steel yog visually indistinguishable. PMI ntawm qhov taw tes ntawm kev teeb tsa ntes qhov yuam kev uas cov ntaub ntawv tsis tuaj yeem.
yuam kev 4:Siv cov ntaub ntawv txheem bolting rau cryogenic flanged pob qij txha.
Txheem ASTM A193 B7 studs (alloy steel) tsis ntsuas rau qhov kub thiab txias. Qhia rau ASTM A320 L7 studs thiab A194 Gr.4 lossis Gr.7 txiv ntseej, uas yog cuam tshuam - kuaj rau −101℃. Rau LNG kev pab cuam ntawm -162 degree, ASTM A320 B8M (316 SS) bolting yuav tsum tau.
yuam kev 5:Tsis txaus thermal cycling tsom xam thaum tsim.
LNG cov nroj tsuag tsis nyob twj ywm ntawm -lub xeev kub. Cooldown thiab sov- nce mus txog - thaum lub sijhawm ua haujlwm, npaj kaw, thiab xwm txheej kub ntxhov - ua rau muaj kev ntxhov siab rau txhua qhov khoom. Ib yam khoom uas muaj zog txaus ntawm qhov ruaj khov- lub xeev tuaj yeem ua rau qaug zog puas tsuaj los ntawm kev rov ua kom sov dua. Qhia cov ntaub ntawv nrog qhov ntsuas qhov ntsuas qhov tsawg kawg nkaus tsawg kawg 10℃hauv qab qhov qis tshaj qhov ntsuas kub ua haujlwm kom muaj kev nyab xeeb.
Cov lus nug nquag
316L stainless hlauNws yog qhov zoo tshaj plaws rau cov kav dej, twj, thiab fittings ntawm -162 degree. Txawm li cas los xij, rau lub tank ntim thawj - uas loj, tuab - phab ntsa siab hlab ntsha - 9% Ni steel thiab Invar membrane yog cov txheej txheem kev daws teeb meem vim tias lawv muab tus nqi ntau dua -kev sib xyaw ua ke ntawm weld- muaj peev xwm, tsim tau yooj yim, thiab cryogenic toughness ntawm qhov ntsuas xav tau rau tso tsheb hlau luam tuav kaum tawm txhiab tus cubic meters.
9% Ni steel (ASTM A553) yog siv rau hauv tag nrho - ntim ob - phab ntsa tso tsheb hlau luam raws li lub plhaub sab hauv, feem ntau 20 mus rau 50 hli tuab, ncaj qha rau ntawm LNG. Invar (Fe-36Ni) muaj cov coefficient tsawg tshaj plaws ntawm thermal expansion thiab yog siv nyob rau hauv nyias-membrane tank tsim (xws li GTT's Mark III thiab No.96 systems) qhov twg cov membrane flexes thiab deforms thaum lub sij hawm thermal cycles tsis tawg. Ob leeg raug txheeb xyuas txog -196 degree; qhov kev xaiv yog tsav los ntawm tank tsim lub tswv yim thiab daim ntawv tso cai pom zoo.
Yog lawm. Aluminium alloy 5083 (ASTM B241) yog dav siv rau LNG txias thawv, kub exchangers, thiab ISO thawv sab hauv cov hlab ntsha. Nws tuav tau zoo toughness ntawm −196 degree, muaj tsawg ntom (txo cov tuag load), thiab tsis yog -magnetic. Nws tsis haum rau siab - cov ntawv thov siab tshaj li ntawm 25 bar yam tsis muaj kev soj ntsuam tsim qauv zoo, tab sis rau qhov nruab nrab - siab cryogenic kev pabcuam nws yog qhov pov thawj thiab tus nqi - kev xaiv zoo.
Xaus
Kev kov yeej qhov qis - qhov kub thiab txias hauv LNG tsob nroj tsis yog ib qho teeb meem ntawm kev nrhiav ib qho khoom siv thoob ntiaj teb - nws yog ib qho teeb meem ntawm kev kos duab txhua thaj chaw cog rau txoj cai alloy, txheeb xyuas cov alloy los ntawm kev sim nruj, thiab tswj kev tsim thiab vuam kom khaws cov khoom koj tau them rau. Lub moj khaum kev txiav txim siab yog qhov tseeb:
Txheeb xyuas qhov ntsuas qhov ntsuas qhov tsawg kawg nkaus rau txhua qhov system thiab cov khoom siv.
Xaiv cov ntaub ntawv uas nws DBTT tau lees paub tias qis dua qhov ntsuas kub los ntawm CVN cov ntaub ntawv cuam tshuam.
Xaiv cov ntaub ntawv FCC (austenitic SS, txhuas) rau cov kav dej; 9% Ni los yog Invar rau cov tso tsheb hlau luam loj.
Qhia thiab tswj PMI ntawm 100% ntawm cov khoom siv alloy ntawm kev teeb tsa.
Tsim nyog rau tag nrho cov txheej txheem weld nrog cryogenic CVN kuaj ntawm weld hlau thiab HAZ.
Siv lub thermal margin: tsim kom tsawg kawg yog 10℃hauv qab qhov qis tshaj qhov ntsuas kub ua haujlwm.
Siv tau tas li, lub moj khaum no tshem tawm cov khoom siv- cuam tshuam txog hom kev ua tsis tiav uas tau ua rau muaj keeb kwm ua rau kev lag luam raug nqi ntau tshaj thiab txaus ntshai. Kev nqis peev ua ntej hauv cov khoom siv raug yog ib txwm tsawg dua tus nqi ntawm ib qho kev ua tsis tiav.
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Npaj rau Qhov Chaw?Peb tsim stainless hlau thiab npib tsib xee alloy yeeb nkab, fittings, thiab flanges rau ASTM A312 (TP304L, TP316L), A182 (F304L, F316L), thiab lwm yam cryogenic specifications, nrog rau tag nrho cov tsis tshua muaj - kub tej yam kev kuaj ntawv pov thawj thiab PMI ntaub ntawv.Hu rau peb pab neeg technicalrau cov khoom muaj nyob, daim ntawv pov thawj cov ntaub ntawv, thiab qhov project- kev txhawb nqa tshwj xeeb. |
ASTM A312 / A 182 - Austenitic Stainless Hlau Yeeb thiab Fittings
ASTM A353 / A 553 - 9% Nickel Steel Phaj (Ob thiab Ib Leeg Ib Leeg & Tempered)
ASTM A320 / A194 - Tsawg-Tsuas Kub Alloy Steel Bolting
ASTM B241 - Aluminium Alloy 5083 Seamless Yeeb thiab Seamless Extruded Tube
ASME B31.3 - Txheej Txheem Piping Code
ASME Tshooj VIII Div.1, Tshooj UHA - Cov Cai rau Austenitic Stainless Steel
API 625 - Tank Systems rau cov tub yees Liquefied Gas Storage
EN 14620 - Tsim thiab Tsim Chaw Tsim Khoom -Ua ntsug LNG Cia Tank
NFPA 59A - Tus Qauv rau Kev Tsim Khoom, Cia, thiab tuav LNG
BS PD 5500 - Specification for Unfired Fusion Welded Pressure Vessels
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