1. Hydrogen Exposure hauv Kev Pabcuam Ib puag ncig
1.1 Roj Hmab: H₂S Reaction-Driven Hydrogen
Hydrogen uptake nyob rau hauv welded pipelines feem ntau accelerates exponentially nyob rau hauv H₂S- nplua nuj qaub ib puag ncig. H₂S tawg rau ntawm cov hlau nto, tsim atomic hydrogen uas diffuses sai rau hauv longitudinal weld seams.
1.2 Corrosion thiab Hydrogen Generation
Cov ntaub ntawv ntub dej H rau ntawm cov hlau los ntawm electrochemical txo. Ntev - lub sij hawm corrosion raug yog li qhov tsis tu ncua hydrogen hauv cov kav dej ntawm LSAW cov khoom.
1.3 Cathodic Protection-Induced Hydrogen Charging
Txawm hais tias kev tiv thaiv cathodic slows tus nqi corrosion, nws ib txhij ua hydrogen ntawm steel nto los ntawm kev txo qis - ironically dhau los ua hydrogen "them" qhov chaw rau welded LSAW seam kev taw qhia.
Table 1: Ib puag ncig vs Hydrogen Ingress Speed
| Kev Pabcuam Ib puag ncig | Hydrogen nkag ceev | Common HIC Region | Kev soj ntsuam zaus |
|---|---|---|---|
| Sweet Natural Gas | Tsawg | Tsis tshua muaj | 2-3 xyoos |
| Wet Corrosive Kab | Nruab nrab | HAZ subsurface | 6–12 lub hlis |
| Sour Gas H₂S Kab | Siab heev | Weld cag, fusion | 3–6 lub hlis |
| Cathodic-Kev Tiv Thaiv Sour Kab | Siab | Seam longitudinal txoj kev | 3–6 lub hlis |
Table 2: Cathodic Protection Level vs Hydrogen Risk
| Kev tiv thaiv muaj peev xwm | Kev tiv thaiv corrosion | Hydrogen tiam | Zuag qhia tag nrho HIC Risk |
|---|---|---|---|
| −0.8 V | Zoo | Nruab nrab | Nruab nrab |
| −1.0 V | Zoo heev | Siab | Siab |
| −1.2 V | Tshaj -Kev tiv thaiv | Siab heev | Siab heev |
2. Txhaum Morphology hauv Sour GasLSAWKab
2.1 Weld Root Dominance
2.1.1 Hauv paus Crack Extension Qauv
Cov kab nrib pleb hauv cov roj qaub LSAW kab feem ntau tshwm sim ntawm cov hauv paus hniav thiab nthuav tawm mus rau sab hauv lub ntsej muag vim yog hydrogen- kev sib koom ua ke.
2.1.2 Blister-Driven Transverse Failures
Hydrogen gas recombination nrog inclusions los yog HAZ voids tuaj yeem ua rau hauv zos trans-segment hlwv, uas tsim kev sib hloov sub- tawg tom qab tig longitudinal nyob rau hauv tensile lag luam kev ntxhov siab.
2.2 Local Hydrogen Pressure Effect
Cov kav dej qaub qaub induce hydrogen gas recombination in void traps - ua rau muaj kev ntxhov siab hauv zos txawm tias kev ntxhov siab hauv cov kav dej ib leeg yog nruab nrab.
3. Kev ntxhov siab sib xyaw ua ke-Hydrogen Interaction hauv Kev Pabcuam
3.1 Internal Pressure Load + Hydrogen
Hydrogen diffused mus rau hauv longitudinal seams sib txuas ua ke nrog cov kua hauv lub siab load hauv LSAW kev pab cuam ua rau quasi-cleavage brittle seam puas nyob rau hauv kev ntxhov siab.
3.2 Sab nraud Load thiab Hydrogen Synergy
Sab nraud loads los ntawm struts, welding residual stress, yeeb nkab faus kev nyuaj siab, los yog siab variation cycles yooj yim ua rau hydrogen - pab cracking synergy ua ntej tshaj nyob rau hauv hydrogen - dawb hlau matrices.
4. Kev tiv thaiv ib puag ncig thiab tshuaj xyuas lub tswv yim
4.1 Txheej los thaiv Hydrogen nkag
Cov yeeb nkab sab nrauv siv hauv hydrogen lossis qaub thauj feem ntau tau txais FBE lossis tiv thaiv -cov kua qaub diffusion txheej kom qeeb atomic hydrogen ingress.
4.2 Kev soj ntsuam xyuas rau Hydrogen Pipelines
Kev ua haujlwm zoo tshaj plaws feem ntau yuav tsum tau siv cov ntaiv ultrasonic- kev tshuaj xyuas tawg → hauv paus notch scan → HAZ subsurface blister check → hydrogen cov ntsiab lus kuaj xyuas → siab voj voog simulation ua raws rau LSAW kav xa mus rau hydrogen lossis H₂S ib puag ncig.
4.3 Ntev-Lub Sij Hawm Muaj Kev Cia Siab
Thaum hydrogen ingress qeeb los ntawm txheej txheej, weld residual stress equilibrated ntawm ci thiab inclusions txo nyob rau hauv lub phaj melting theem, kev pab cuam lub neej zoo heev rau hydrogen thauj chains - txawm nyob rau hauv qaub roj los yog cathodic - kab tiv thaiv.
