Hydrogen Induced Cracking (HIC) yog dab tsi?
Hydrogen induced cracking yog ib hom kev puas tsuaj ntawm hydrogen uas tshwm sim hauv cov pa roj carbon thiab qis - alloy hlau thaum atomic hydrogen nkag mus rau hauv cov khoom los ntawm ib puag ncig corrosive, feem ntau cov kev pabcuam ntub dej uas muaj hydrogen sulfide (H₂S). Nyob rau hauv cov roj thiab roj pipeline, H₂S reacts nrog hlau ntawm steel nto thiab tso tawm atomic hydrogen. Cov hydrogen atoms diffuse mus rau hauv cov hlau thiab recombine rau hauv molecular hydrogen nyob rau hauv lub discontinuities xws li elongated manganese sulfide inclusions, centerline segregation los yog pawg oxides. Vim hais tias molecular hydrogen tsis tuaj yeem nthuav tawm rov qab, nws ua rau lub siab sab hauv uas tuaj yeem ua rau lub ntsej muag thiab pib ua kom tawg ntawm phab ntsa tuab.
HIC yog qhov txawv ntawm sulfide stress cracking (SSC): SSC yuav tsum muaj tensile stress thiab tshwm sim nyob rau hauv siab -hardness los yog siab - lub zog microstructures, thaum HIC tuaj yeem txhim kho yam tsis muaj kev ntxhov siab sab nraud thiab nyob ntawm cov hlau kev huv, suav nrog morphology thiab microstructure. Ob hom kev ua tsis tiav yog hais txog thaum cov yeeb nkab raug xaj rau kev pabcuam qaub.
HIC Requirements hauv API 5L Specification
Raws li API 5L, HIC xeem tsis yog daim pam yuav tsum tau rau txhua lub yeeb nkab. Nws siv rau PSL 2 qib xaj nrog qaub- kev pabcuam, uas tau qhia los ntawm tsab ntawvShauv qib npe, piv txwv li X52MS, X60MS, X65MS, X65QS thiab X70QS. Hauv cov npe no, M txheeb xyuas cov khoom siv thermomechanically dov thiab Q qhia cov khoom quenched thiab tempered; S suffix txhais tau hais tias cov yeeb nkab tau teev tseg rau kev tiv thaiv hydrogen induced cracking hauv H₂S ib puag ncig. HIC cov kev cai xeem rau cov qib no tau teev tseg nyob rau hauv Annex B ntawm API 5L, nrog rau cov txheej txheem xeem tau ua raws li NACE TM0284, tus qauv txheej txheem rau kev soj ntsuam cov raj xa dej rau kev tiv thaiv hydrogen induced cracking.
| Yam khoom | Yam yuav tsum tau muaj |
|---|---|
| Cov khoom siv tau | PSL 2 yeeb nkab nrog S qaub- kev pabcuam kev pabcuam, xws li X52MS, X65MS, X65QS |
| Kev sim | TIAB SA TM0284 |
| Crack Length piv (CLR) | max 15% |
| Crack thickness ratio (CTR) | max 5% |
| Crack rhiab heev ratio (CSR) | max 2% |
CLR, CTR thiab CSR txwv nyob rau hauv lub rooj yog qhov kev lees paub qhov tseem ceeb uas feem ntau siv hauv API 5L Annex B kev yuav khoom specifications. Cov kev lees txais zaum kawg yog ib txwm txhais nyob rau hauv qhov kev txiav txim yuav khoom thiab qhov project specification, uas tej zaum yuav teem nruj me ntsis rau cov kev pab cuam hnyav.
Dab tsi CLR, CTR thiab CSR ntsuas
Tom qab qhov kev xeem, cov qauv yog txiav thiab kuaj metallographically. Peb qhov sib piv yog xam los ntawm cov kab nrib pleb uas tau pom nyob rau ntawm ntu ntsej muag:
| Qhov taw qhia | Txhais |
|---|---|
| CLR (kav ntev piv) | Cov txiaj ntsig ntawm qhov tawg ntev ntawm lub ntsej muag kuaj tau muab faib los ntawm tag nrho lub ntsej muag dav |
| CTR (kab thickness ratio) | Qhov sib npaug ntawm cov kab nrib pleb sib faib los ntawm cov qauv phab ntsa thickness |
| CSR (Crack rhiab heev piv) | Qhov sib npaug ntawm (kav ntev x tawg thickness) rau txhua qhov tawg muab faib los ntawm (lub ntsej muag dav x phab ntsa thickness) |
CLR qhia txog ntau npaum li cas ntawm seem dav puas lawm, CTR qhia txog tias cov kab nrib pleb zoo li cas los nkag mus rau phab ntsa, thiab CSR muab ob qho tib si rau hauv ib qho kev ntsuas qhov ntsuas siab. Ib cov yeeb nkab uas ua tau raws li tag nrho peb qhov kev txwv yog suav tias tiv taus HIC rau qhov kev sim.
Test Conditions rau NACE TM0284
NACE TM0284 xeem exposes machined specimens mus rau acidified saline tov saturated nrog hydrogen sulfide. Tus qauv xeem ib puag ncig yog tshuaj A, suav nrog 5% sodium chloride thiab 0.5% acetic acid hauv dej distilled, saturated nrog H₂S ntawm qhov kub ntawm 25 ± 3℃rau 96 teev. Kev daws B, uas tsis muaj acetic acid thiab pib ntawm pH siab dua, yog siv thaum teev los ntawm tus neeg yuav khoom los sawv cev tsis tshua muaj kev mob hnyav. Cov qauv no feem ntau yog coj los ntawm cov hlau hauv paus, thiab rau cov yeeb nkab welded los ntawm qhov chaw vuam thiab cov cua sov cuam tshuam zoo ib yam, vim tias cov seam feem ntau yog qhov xav tau tshaj qhov chaw rau qaub- kev pabcuam kev pabcuam. Tom qab kis tau, cov qauv raug muab faib thiab tshuaj xyuas rau blistering thiab tawg raws li tau piav qhia saum toj no.
Metallurgical Factors uas tswj HIC Resistance
HIC tsis kam yog txiav txim siab ntawm lub steelmaking thiab dov theem, tsis yog los ntawm kev soj ntsuam ib leeg. Cov hauv qab no muaj feem cuam tshuam loj tshaj plaws:
| Qhov xwm txheej | Qhov cuam tshuam rau HIC Resistance |
|---|---|
| Cov ntsiab lus sulfur | Tsawg S, feem ntau 0.003% lossis tsawg dua rau qib qaub, txo qis manganese sulfide suav nrog qhov twg hydrogen khaws |
| Calcium kho | Sulphides residual sulfides rau hauv me me, globular, tsis yog -deformable inclusions uas tsis elongate thaum dov |
| Phosphorus thiab cais | Tsawg P thiab txo qhov nruab nrab ntawm kev sib cais txwv tsis pub muaj cov qauv uas ua raws li txoj kev tawg |
| Kev huv huv | Kev tswj nruj ntawm oxides thiab lwm yam kev suav nrog txo qhov chaw pib tawg |
| Microstructure | Uniform ferrite-pearlite los yog acicular ferrite tsis muaj zog bands txhim kho kev tiv thaiv |
| Microalloying | Nb, V thiab Ti refine grain loj thiab txhawb tswj dov |
| Rolling thiab kev ua kom txias | Tswj dov thiab txias, suav nrog hauv online normalizing qhov twg siv tau, tsim cov qauv homogeneous |
Thaum cov kev tswj hwm no tau siv ua ke, cov hlau tiv thaiv hydrogen tsub zuj zuj thiab tawg tawm, uas yog vim li cas qaub - cov kav dej ua haujlwm tau tsim los rau kev ua haujlwm melting thiab dov es tsis yog sim los ntawm cov khoom lag luam.
Yuav Ua Li Cas HIC Kev Ua Haujlwm Zoo Tshaj Plaws hauv Kev Xyaum
Kev tsim nyog feem ntau ua raws li ob - theem kev. Ua ntej, lub zeb ua cov hom lossis kev tsim nyog kuaj kom pom tias txoj kev tsim khoom tuaj yeem ua tau raws li qhov xav tau CLR, CTR thiab CSR qhov tseem ceeb. Tom qab ntawd, ntau-los ntawm-ntau lossis cua sov- los ntawm- kev ntsuas kub yog ua rau cov yeeb nkab ntau lawm raws li tau pom zoo hauv daim ntawv xaj yuav khoom, feem ntau pom los ntawm peb lub koom haum soj ntsuam thib peb -. Kev kuaj xyuas ultrasonic ntxiv ntawm tag nrho cov yeeb nkab lub cev kuj tseem tuaj yeem raug teev los kuaj xyuas cov laminations lossis kev cuam tshuam sab hauv uas tuaj yeem cuam tshuam rau qaub- kev pabcuam kev ua haujlwm.
Vim li cas HIC Requirements Matter hauv Pipeline Engineering
Cov kav dej uas nqa cov roj ntub lossis roj av nrog H₂S ua haujlwm nyob rau hauv cov xwm txheej uas tuaj yeem degrade cov pa roj carbon zoo tib yam hauv lub sijhawm luv. Yog tias HIC txhim kho, cov hlwv thiab cov kab nrib pleb sab hauv ua rau cov phab ntsa tsis muaj zog thiab tuaj yeem ua rau tawg lossis tawg yam tsis muaj kev ceeb toom. Kev qhia API 5L PSL 2 qaub- cov yeeb nkab kev pabcuam nrog HIC kev ua tau zoo tiv thaiv cov qauv kev ncaj ncees ntawm txoj kab, txuas ntxiv cov sijhawm tshuaj xyuas thiab kev pabcuam lub neej, thiab txo cov kev pheej hmoo ntawm kev ua tsis tiav thiab ib puag ncig.
FAQ
Puas yog HIC xeem yuav tsum tau ua rau tag nrho API 5L yeeb nkab?
Tsis yog. Kev kuaj HIC tsuas yog yuav tsum tau ua thaum cov yeeb nkab raug txiav txim rau PSL 2 qaub- qib kev pabcuam nrog S tus qauv, lossis thaum qhov kev yuav khoom tshwj xeeb hu rau nws. Standard API 5L PSL 1 lossis PSL 2 yeeb nkab yam tsis muaj S xaiv tsis raug rau Annex B HIC xeem.
Qhov txawv ntawm HIC thiab SSC yog dab tsi?
HIC yog tsav los ntawm lub zog hydrogen sab hauv ntawm kev suav nrog thiab tsis tas yuav muaj kev ntxhov siab sab nraud. SSC, sulfide kev ntxhov siab tawg, yuav tsum muaj kev ntxhov siab tensile thiab feem ntau tshwm sim hauv cov txheej txheem nyuaj; Nws raug soj ntsuam los ntawm lwm txoj kev sim, NACE TM0177.
Cov qib API 5L twg muaj qhov S qaub- kev pabcuam?
PSL 2 qib xws li X52MS, X56MS, X60MS, X60QS, X65MS, X65QS, X70MS thiab X70QS tuaj yeem txiav txim nrog S suffix thaum qaub- kev pabcuam yuav tsum tau ua.
NACE TM0284 HIC xeem siv sijhawm ntev npaum li cas?
Tus qauv raug yog 96 teev nyob rau hauv qhov kev ntsuam xyuas kev daws teeb meem ntawm 25 ± 3 degree, tom qab uas cov qauv yog sectioned, polished thiab kuaj metallographically. Nrog rau kev npaj thiab kev ntsuam xyuas, ib qho kev xeem tag nrho feem ntau yuav siv li ib lub lis piam.
Puas tuaj yeem welded API 5L yeeb nkab dhau HIC kuaj?
Yog lawm. Rau cov yeeb nkab welded, cov qauv raug coj los ntawm cov hlau hauv paus thiab los ntawm cov vuam seam thiab tshav kub cuam tshuam cheeb tsam. Lub seam feem ntau yog qhov chaw tswj, yog li cov khoom siv vuam siv, cov khoom siv hluav taws xob thiab cov khoom xa tawm -weld condition raug tswj raws li ib feem ntawm qaub- kev pabcuam kev pabcuam.
Dab tsi CLR, CTR thiab CSR qhov tseem ceeb yuav tsum tus neeg yuav khoom qhia?
Qhov feem ntau siv API 5L Annex B qhov tseem ceeb yog CLR max 15%, CTR max 5% thiab CSR max 2%. Rau cov kev pabcuam hnyav tshwj xeeb, cov neeg yuav khoom tuaj yeem tsim cov kev txwv nruj dua, yog li cov txiaj ntsig yuav tsum tau hais meej meej hauv kev yuav khoom.
