Cov kev pabcuam qaub steel yeeb nkab yog siv rau cov kav dej hauv qhov chaw corrosive.Raws li peb paub, kab yeeb nkab corrosion yog qhov tseem ceeb cuam tshuam rau nws txoj kev nyab xeeb thiab kev pabcuam lub neej. Nws yuav ua rau cov roj thiab cov kav dej xau, qee kis txawm tias tawg.
Cov yeeb nkab corrosion muaj kev hem thawj rau tus kheej kev nyab xeeb thiab ib puag ncig muaj kuab paug, yog li kev tsim cov kua qaub cov yeeb nkab yog qhov tseem ceeb. Tam sim no, kev tsim tshuaj xyuas tus qauv rau cov kua qaub yeeb nkab feem ntau raws li API Spec 5L.
Sour Service Pipe Txhais
Cov kav dej qab zib feem ntau siv hauv H2S ib puag ncig. Thaum H2S yog cov tshuaj phem uas feem ntau yooj yim los tsim cov corrosion.
Raws li kev cai thoob ntiaj teb: Thaum ib nrab siab ntawm H2S nce mus txog 300 pa, cov kav dej siv yuav tsum muaj cov tshuaj tiv thaiv -acid corrosion ua haujlwm.Sour cov yeeb nkab muaj xws li NACE yeeb nkab (NWS MR0175).
Yuav Ua Li Cas Sour Service Pipe Ua
Hauv API Spec 5L, cov yeeb nkab steel siv rau cov kav dej qaub yog purity tag nrho -tua steel. (Rau ib txwm kab yeeb nkab steel khoom yog nplej -tua steel)
Nws yuav tsum raug sau tseg tias, lub siab purity ntawm hlau tuaj yeem lav qis S, P thiab lwm yam impurities.
Tsis tas li ntawd, tus txheej txheem rau kev tswj thiab tshuaj xyuas ntawm cov qauv ntawm cov yeeb nkab steel rau cov kav dej qaub yog xav tau. Vim tias hydrogen induced cracking tshwm sim los ntawm kev suav nrog yog thawj zaug txiav txim hauv nws daim ntawv.
Ntxiv mus, Raws li cov yeeb nkab steel ntau lawm feem ntau txais kev tswj cov txheej txheem dov. Inclusion tshwm sim deformation thaum lub sij hawm dov txheej txheem. Nws yog hu ua linear lossis ntev strips nyob rau hauv cov kev taw qhia dov, ua rau anisotropy ntawm kab yeeb nkab steel. Yog li ntawd, txhawm rau txhim kho corrosion kuj ntawm steel kab yeeb nkab, daim ntawv slag yuav tsum tau tswj.
Chemical zog ntawm qaub Service yeeb nkab
Cov ntsiab lus ntawm C, P, S thiab carbon sib npaug hauv cov tshuaj muaj pes tsawg leeg ntawm cov kav dej qaub yog qhov qis dua li cov kav dej ib txwm muaj, nrog rau kev tswj hwm nruj. Tshwj xeeb tshaj yog rau cov ntsiab lus S, nws yog ib qho teeb meem tsis zoo nyob rau hauv cov cheeb tsam corrosion, yog li rau cov kav dej qaub yuav tsum tswj S siab tshaj 0.002.
API 5L Sour Service yeeb nkab Chemical Composition
. C thiab carbon sib npaug cuam tshuam rau cov kav dej qaub
C thiab carbon sib npaug: Nrog rau qhov loj ntawm cov pa roj carbon ntau ntxiv, HIC rhiab heev nce. Kev txo qis ntawm cov pa roj carbon monoxide thiab carbon sib npaug tuaj yeem txhim kho H2S corrosion tsis kam ntawm cov kav dej hlau. Thiab nws yuav tsim kom muaj teeb meem martensite qauv, uas yog rhiab heev rau H npuas rau cov kub dov hlau.
. P element rau qaub kav
Cov khoom P yog ib qho yooj yim rau kev sib cais, yog li qhov nce ntawm phosphorus pawg feem ntau yuav ua rau kev nce ntawm cov qauv banded, yog li ua kom cov rhiab heev ntawm cov hlau HIC.
. S element nyhuv rau qaub yeeb nkab
S lub ntsiab tuaj yeem txhawb qhov tshwm sim ntawm HIC, qhov siab dua cov ntsiab lus ntawm cov khoom siv hauv cov yeeb nkab lub cev, qhov yooj yim los tsim HIC. Tsis tas li ntawd, kev tiv thaiv - SSC kev ua haujlwm ntawm cov kav dej uas muaj cov ntsiab lus sulfur siab tsis zoo.
. Mn ntsiab
Txhawm rau kom ntseeg tau cov ntsiab lus carbon hauv qib siab pipeline steel, manganese feem ntau yog siv los txhim kho nws lub zog. Kev cuam tshuam ntawm manganese ntawm HIC tsis kam ntawm cov yeeb nkab steel feem ntau muab faib ua peb hom:
Kub dov kab yeeb nkab steel nrog cov ntsiab lus carbon ntawm 0.05% ~ 0. 15 %
Thaum cov ntsiab lus manganese yog 1. 0 %, HIC rhiab heev yuav nce sai:
Rau quenched thiab tempered kab yeeb nkab steel
Thaum cov ntsiab lus ntawm manganese nce mus txog 1.6%, lub siab tsis kam ntawm cov hlau tsis cuam tshuam los ntawm manganese.
Yog tias cov ntsiab lus carbon tsawg dua 0.02%
Yog tias cov pa roj carbon tsawg dua 0.02%, txawm tias cov ntsiab lus manganese ntau dua 2.0%, cov yeeb nkab tseem muaj HIC zoo.
Hardness xav tau ntawm qaub kev pab cuam yeeb nkab
Lub hardness ntawm cov kav dej qaub yog nruj, vim hais tias tus nqi hardness muaj qhov cuam tshuam zoo rau HIC. Cov txiaj ntsig tau pom tias nyob rau hauv qis thiab nruab nrab lub zog steels, cov khoom siv zog ntau dua, qhov nyuaj dua, qhov muaj zog ntawm HIC rhiab heev.
Corrosion xeem
Hauv API 5L rau cov kav dej qaub, tus nqi hardness ntawm lub hauv paus hlau, vuam thiab kub cheeb tsam yuav tsum tsis pub tshaj 250 HV10. Lub hardness ntawm cov qaub qhov kev pab cuam yeeb nkab yog nruj dua, vim hais tias cov hardness tus nqi muaj feem xyuam rau HIC ntau dua. Kev tshawb fawb qhia tau hais tias qhov siab dua cov khoom siv zog, qhov hardness ntau dua, qhov muaj zog HIC rhiab heev nyob rau hauv qis thiab nruab nrab lub zog steel.
Mechanical zog ntawm API 5L yeeb nkab rau qaub kev pab cuam
