Q1: Dab tsi yog qhov corrosion mechanism ntawm A335 steel yeeb nkab hauv qhov kub thiab txias sulfidation ib puag ncig?
In oil products containing H₂S, A335 steel pipe will undergo high temperature sulfur corrosion (H₂S+Fe→FeS+H₂), forming a loose iron sulfide film, resulting in continuous thinning. P5 steel contains 5% Cr, which is 3~5 times more corrosion resistant than carbon steel, but the wall thickness still needs to be monitored when the temperature is >260 Qib. Tus nqi corrosion yog qhov sib cuam tshuam nrog lub h₂s ib nrab ntawm siab, txaus tus nqi thiab cov ntsiab lus hauv Cry. Kev tiv thaiv kev tiv thaiv suav nrog kev txhaj tshuaj tiv thaiv corrosion inhibitors thiab tswj tus nqi txaus rau<15m/s. Regular UT thickness measurement is necessary, and the remaining wall thickness must meet the ASME B31G calculation requirements.
Q2: Yuav ua li cas txhawm rau txhim kho lub corrosion tsis kam ntawm A335 los ntawm cov thev naus laus zis thev naus laus zis li cas?
Lub puab txheej yuav tuaj yeem tsom iav Epxy (qhov kub tsis kam dua lossis sib npaug nrog 120 degree) lossis zinc tsawg dua lossis sib npaug nrog rau cov dej phipelines. Fusion (fusion bonded epoxy) lossis 3LPE (peb-txheej polyethylene) feem ntau siv rau kev tiv thaiv corrosion sab nraud, thiab kev nyiam huv. Rau qhov ntsuas kub siab, txhuas lossis chromium alloy (xws li 80ni20r) tuaj yeem ua rau txheej txheej oxidation olidation. Cov kab xev sib tw sib luag (ntau dua los yog sib npaug rau 5kv DC CAPE) yog qhov yuav tsum tau ua tom qab kev tsim kho. Saib xyuas yuav tsum tau them rau qhov sib raug zoo ntawm cov txheej nrog kev tiv thaiv ntxig rau kev zam kom tsis txhob tev.
Q3: Dab tsi media tuaj yeem ua rau muaj kev ntxhov siab corrosion ntawm A335 cov kav hlau steel?
Ntub dej h₂s ib puag ncig (> 50ppm) tuaj yeem ua rau Scc (yuav tsum tau ntsib NACE MR0175 txheem). Kev daws qhov kub kub (xws li Naoh Alkali Kev daws (xws li NAAH>, Kub> Qib Siab) Yuav Ua Kom Alkali Postrementlement, tshwj xeeb yog nyob hauv thaj chaw weld. Polythionic acid (h ₂sₓo₆, tsim thaum lub sij hawm kaw) ua rau muaj kev hem thawj loj heev rau WelSustenitic Stainless Hlau thiab A335 dissimilar hlau. CO₂-Co-H₂o System kuj tseem tuaj yeem ua rau tawg rau qee hom PH. Kev tiv thaiv kev tiv thaiv suav nrog kev txo qis kev ntxhov siab, tswj cov kev coj dawb huv thiab ntxiv cov neeg tsis muaj neeg inibitors.
Q4: Puas yog Austeniting txhim kho cov oxidation tiv thaiv ntawm A335?
Austenitizing (xws li quenching p91 steel ntawm 1040 degree) tuaj yeem kho cov nplej, nce solubility ntawm chromium, thiab txhim kho cov qib siab-oxidation kuj. Cov yeeb yaj kiab ntom nthe ua yeeb yaj kiab tom qab kev kho mob tuaj yeem tiv thaiv chav oxidation saum toj 600 degree. Txawm li cas los xij, tempering (xws li 780 degree) yuav tsum zam kom tsis txhob brittleness. Hauv cov ntawv thov tiag tiag, tus lej oxidation ntawm P91 Hlau Tom qab ib txwm + Tempering yog 30% 2% qis dua li ntawm P22. Nws yuav tsum raug sau tseg tias kev ua yeeb yaj kiab ntawm oxide zaj duab xis yuav ua rau yaig oxide yuav ua rau cov dej ntws tawm ntawm cov dej khov kho, ect) yog qhov yuav tsum tau ua.
Q5: Yuav ua li cas txheeb xyuas ntawm phab ntsa thickness them zoo li A335 steel kav hauv kev pabcuam?
Cov hau kev pab cuam muaj xws li ultrasonic thickness ntsuas (UT, kev soj ntsuam ± 0.1mm), thiab tees-taw tes saib lub luj tshib txhua txhua 3 hlis. Pulsed Eddy tam sim no (PEC) siv tau rau hauv thaj chaw kub uas tsis muaj txheej txheem rwb thaiv tsev. X-Rooth Dr kom tau txais yuav tuaj yeem ua ke nrog phab ntsa tuab npuaj software los tsim cov duab peb-seem corrosion. Rau sab hauv ntawm cov raj xa dej, cov ntse siv cov yeeb nkab ntxuav (npua) nruab nrog electromagnetic lossis ultrasonic probes tuaj yeem ua tiav kev kuaj ntev ntev. Cov ntaub ntawv yuav tsum tau sau tseg thiab piv nrog ASME B31G Residual Dag mis los ntsuas lub neej.
