Cov kav dej muaj peev xwm muab faib ua cov kav hlau thiab cov kav uas tsis yog hlau. Cov kav hlau kuj muab faib ua cov hom hlau thiab cov hom hlau tsis yog hlau. Cov hlau hlau feem ntau yog ua los ntawm hlau, thaum cov hlau tsis yog hlau tsis yog hlau. Cov kav hlau carbon, cov kav hlau stainless hlau, cov kav hlau chrome molybdenum thiab cov kav hlau cam khwb cia yog cov kav hlau ferrous uas muaj hlau ua lub ntsiab. Cov kav hlau nickel thiab nickel alloy, nrog rau cov kav hlau tooj liab, yog cov kav hlau tsis yog hlau. Cov kav hlau yas, cov kav hlau ua los ntawm pob zeb, cov kav hlau yas, cov kav hlau iav, cov kav hlau ua los ntawm pob zeb thiab lwm cov kav hlau tshwj xeeb uas siv tau rau cov hom phiaj tshwj xeeb hu ua cov kav hlau tsis yog hlau. Cov kav hlau ferrous yog cov kav hlau siv dav tshaj plaws hauv kev lag luam fais fab; cov kav hlau carbon siv dav heev. Cov qauv ASTM thiab ASME tswj hwm ntau yam kav hlau thiab cov khoom siv kav hlau siv hauv kev lag luam txheej txheem.
Cov hlau carbon yog cov hlau siv ntau tshaj plaws hauv kev lag luam, suav txog ntau dua 90% ntawm tag nrho cov hlau tsim tawm. Raws li cov ntsiab lus carbon, cov hlau carbon raug muab faib ua peb pawg:
Hauv cov hlau alloyed, cov feem sib txawv ntawm cov ntsiab lus alloying yog siv los ua tiav cov khoom xav tau (txhim kho) xws li weldability, ductility, machinability, lub zog, hardenability thiab corrosion resistance, thiab lwm yam. Qee cov ntsiab lus alloying feem ntau siv thiab lawv lub luag haujlwm yog raws li nram no:
Cov hlau tsis xeb yog cov hlau sib xyaw uas muaj cov chromium ntsiab lus ntawm 10.5% (yam tsawg kawg nkaus). Cov hlau tsis xeb ua rau muaj kev tiv thaiv xeb zoo heev vim yog kev tsim cov txheej Cr2O3 nyias heev ntawm qhov chaw. Cov txheej no kuj hu ua txheej passive. Kev nce cov chromium ntau ntxiv yuav txhim kho qhov kev tiv thaiv xeb ntawm cov khoom. Ntxiv rau chromium, nickel thiab molybdenum raug ntxiv los muab cov yam ntxwv xav tau (lossis txhim kho). Cov hlau tsis xeb kuj muaj ntau yam carbon, silicon thiab manganese. Cov hlau tsis xeb raug cais ua:
Ntxiv rau cov qib saum toj no, qee cov qib siab heev (lossis qib tshwj xeeb) cov hlau tsis xeb kuj siv hauv kev lag luam yog:
Cov hlau siv rau cov cuab yeej muaj cov pa roj carbon ntau (0.5% txog 1.5%). Cov pa roj carbon ntau dua ua rau muaj qhov tawv thiab lub zog ntau dua. Cov hlau no feem ntau yog siv los ua cov cuab yeej thiab pwm. Cov hlau siv rau cov cuab yeej muaj ntau yam tungsten, cobalt, molybdenum, thiab vanadium kom ua rau cov hlau kub thiab tiv taus kev hnav thiab ua kom ruaj khov. Qhov no ua rau cov hlau siv rau cov cuab yeej txiav thiab khawb.
Cov kav dej no siv dav hauv kev lag luam txheej txheem. ASTM thiab ASME cov npe rau cov kav dej zoo li txawv, tab sis cov qib khoom siv zoo ib yam. Piv txwv li:
Cov khoom siv thiab cov khoom ntawm ASME thiab ASTM cov lej zoo ib yam tsuas yog lub npe xwb. Lub zog tensile ntawm ASTM A 106 Gr A yog 330 Mpa, ASTM A 106 Gr B yog 415 Mpa, thiab ASTM A 106 Gr C yog 485 Mpa. Cov yeeb nkab carbon steel feem ntau siv yog ASTM A 106 Gr B. Muaj lwm txoj hauv kev rau ASTM A 106 Gr A 330 Mpa, ASTM A 53 (Kub Dip Galvanized lossis Kab Yeeb Nkab), uas kuj yog qib siv dav hauv cov yeeb nkab carbon steel rau yeeb nkab. ASTM A 53 yeeb nkab muaj ob qib:
ASTM A 53 Yeeb Nkab muaj peb hom - Hom E (ERW - Tiv Thaiv Welded), Hom F (Cua Tshuab thiab Butt Welded), Hom S (Seamless). Hauv Hom E, ob qho tib si ASTM A 53 Gr A thiab ASTM A 53 Gr B muaj. Hauv Hom F, tsuas yog ASTM A 53 Gr A muaj, thaum nyob rau hauv Hom S, ASTM A 53 Gr A thiab ASTM A 53 Gr B kuj muaj. Lub zog tensile ntawm ASTM A 53 Gr A yeeb nkab zoo ib yam li ASTM A 106 Gr A ntawm 330 Mpa. Lub zog tensile ntawm ASTM A 53 Gr B yeeb nkab zoo ib yam li ASTM A 106 Gr B ntawm 415 Mpa. Qhov no npog cov yeeb nkab carbon steel uas siv dav hauv kev lag luam txheej txheem.
Cov kav dej hlau tsis xeb uas siv ntau tshaj plaws hauv kev lag luam ua khoom hu ua austenitic stainless steels. Qhov tseem ceeb ntawm austenitic stainless steel yog tias nws tsis yog magnetic lossis paramagnetic. Peb qhov tseem ceeb rau austenitic stainless steels yog:
Muaj 18 qib hauv cov lus qhia no, uas 304 L yog qhov siv ntau tshaj plaws. Ib pawg nrov yog 316 L vim nws tiv taus corrosion siab. ASTM A 312 (ASME SA 312) rau cov kav dej 8 nti lossis tsawg dua hauv txoj kab uas hla. Tus "L" nrog rau qib qhia tias nws muaj cov pa roj carbon tsawg, uas txhim kho qhov weldability ntawm cov kav dej qib.
Cov lus qhia no siv rau cov kav dej loj uas vuam. Cov txheej txheem kav dej uas tau them rau hauv cov lus qhia no yog Daim Ntawv Teev Npe 5S thiab Daim Ntawv Teev Npe 10.
Kev Sib Txuas Lus ntawm Austenitic Stainless Steels - Austenitic stainless steels muaj kev nthuav dav thermal ntau dua li ferritic lossis martensitic stainless steels. Vim yog qhov coefficient siab ntawm thermal expansion thiab qis thermal conductivity ntawm austenitic stainless steel, deformation lossis warpage tuaj yeem tshwm sim thaum lub sijhawm vuam. Austenitic stainless steel yog qhov yooj yim rau solidification thiab liquefaction cracking. Yog li ntawd, yuav tsum tau ceev faj thaum xaiv cov ntaub ntawv filler thiab cov txheej txheem vuam. Submerged arc welding (SAW) tsis pom zoo thaum xav tau tag nrho austenitic stainless steel lossis qis ferrite welds. Lub rooj (Appendix-1) yog ib daim ntawv qhia rau kev xaiv cov hlau filler lossis electrode raws li cov khoom siv hauv paus (rau austenitic stainless steels).
Chromium molybdenum tubing yog tsim rau cov kab kev pabcuam kub siab vim tias lub zog tensile ntawm chrome molybdenum tubing tseem tsis hloov pauv thaum kub siab. Lub raj pom daim ntawv thov hauv cov chaw tsim hluav taws xob, cov cua sov sib pauv, thiab lwm yam. Lub raj yog ASTM A 335 hauv ntau qib:
Cov kav dej hlau cam khwb cia yog siv rau kev tua hluav taws, dej ntws tawm, dej phwj tuaj, ua haujlwm hnyav (hauv qab ua haujlwm hnyav) - cov kav dej hauv av thiab lwm yam kev pabcuam. Cov qib ntawm cov kav dej hlau cam khwb cia yog:
Cov kav dej hlau uas siv tau rau hauv av rau kev tua hluav taws. Cov kav dej Dürr nyuaj vim muaj silicon. Cov kav dej no siv rau kev pabcuam kua qaub lag luam, vim tias qib qhia tau tias tiv taus kua qaub lag luam, thiab rau kev kho dej uas tso cov kua qaub pov tseg.
Nirmal Surendran Menon tau txais daim Bachelor of Mechanical Engineering los ntawm Anna University, Tamil Nadu, Is Nrias teb xyoo 2005 thiab Master of Science hauv Project Management los ntawm National University of Singapore xyoo 2010. Nws nyob hauv kev lag luam roj/gas/petrochemical. Tam sim no nws ua haujlwm ua tus kws ua haujlwm hauv thaj chaw ntawm LNG liquefaction project hauv sab qab teb sab hnub poob Louisiana. Raws li ib feem ntawm kev ua tiav project, nws nyiam suav nrog kev ntxuav cov kav dej thiab kev tiv thaiv kev poob rau LNG liquefaction facilities.
Ashish muaj daim bachelor's degree hauv engineering thiab muaj ntau tshaj 20 xyoo ntawm kev koom tes hauv kev tsim kho, kev lees paub zoo / kev tswj hwm zoo, kev tsim nyog / kev saib xyuas cov neeg muab khoom, kev yuav khoom, kev npaj cov peev txheej tshuaj xyuas, kev vuam, kev tsim khoom, kev tsim kho thiab kev cog lus ua haujlwm.
Cov haujlwm roj thiab roj av feem ntau nyob rau thaj chaw deb ntawm lub hauv paus chaw ua haujlwm ntawm lub tuam txhab. Tam sim no, nws muaj peev xwm saib xyuas kev ua haujlwm ntawm lub twj tso kua mis, npaj thiab tshuaj xyuas cov ntaub ntawv av qeeg, thiab taug qab cov neeg ua haujlwm thoob plaws ntiaj teb los ntawm txhua qhov chaw. Txawm hais tias cov neeg ua haujlwm nyob hauv chaw ua haujlwm lossis nyob deb, Is Taws Nem thiab cov ntawv thov cuam tshuam ua rau muaj kev ntws thiab tswj cov ntaub ntawv ntau txoj kev ntau dua li yav dhau los.
Sau npe rau OILMAN Niaj hnub no, tsab ntawv xov xwm ob zaug ib lim tiam xa tuaj rau koj lub inbox nrog txhua yam koj xav paub txog xov xwm lag luam roj thiab roj av, cov xwm txheej tam sim no thiab cov ntaub ntawv kev lag luam.