Cov Tswv Yim Tseem Ceeb: Lub hom phiaj ntawm PWHT
Ua ntej, nws yog qhov tseem ceeb kom nkag siab yog vim li cas pwht yog siv. Nws cov hom phiaj tseem ceeb yog:
Hais txog kev nyuaj siab:Txhawm rau txo cov kev ntxhov siab uas muaj kev ntxhov siab vim yog los ntawm vuam thiab cov hlua.
Hardness tswj:Kom npau taws lub zog, brittle microstructure nyob rau hauv cov tshav kub -} kev cuam tshuam thaj chaw (hz), txhim kho kev muaj zog.
Hydrogen Tshem Tawm:Txhawm rau tsav tawm hydrogen qhia thaum lub vuam, tiv thaiv hydrogen -}}).
Yam cuam tshuam rau qhov kev xav tau ntawm kev siv hluav taws xob
1. Khoom siv tuab (thawj qhov tseem ceeb)
Qhov no feem ntau yog qhov txiav txim siab tshaj plaws hauv cov cim thiab cov qauv.
Thinner gauges (< ~3/4 in. or 19 mm):Residual kev nyuaj siab yog qis dua thiab tuaj yeem ua rau kev txhawb nqa los ntawm cov khoom siv. Kev pheej hmoo ntawm brittle bacture kuj qis dua.PWHT yog feem ntau tsis tas yuav.
Thicker ntu (ntau dua lossis sib npaug ntawm ~ 3/4 hauv. Lossis 19 hli):Cov kev ntxhov siab siab yog muab xauv cia rau hauv thiab tsis tuaj yeem raug txim siab ib txwm muaj. Txoj kev pheej hmoo ntawm kev tawg (tshwj xeeb yog hydrogen cracking) thiab brittle bacture nce ntau.PWHT feem ntau yuav tsum tau uaRaws li cov lej lis haujlwm (piv txwv li, AWS AWS D1.1, ASME BPVC, API cov qauv).
2. Tshuaj lom neeg sib xyaw ua ke thiab cov pa roj carbon sib npaug (CE)
Weathering hlau muaj cov alloys tshwj xeeb (Cu, P, Cr, NI) rau corrosion kuj, uas cuam tshuam rau weldability.
Carbon sib npaug (CEV):Ib qho siab dua ntawm Weldability thiab muaj kev pheej hmoo siab dua ntawm kev tsim nyuaj, tawg {}} rhiab microstructures hauv lub haz. Thaum huab cua cov hlau hluav taws xob feem ntau muaj kev sib tw kom tsawg dua, nws yuav tsum tau xam. Yog lub cev yog siabthiabLub thickness yog qhov tseem ceeb, pwh dhau los ua tus tseem ceeb dua.
Phosphorus (p) cov ntsiab lus:Weathering hlau muaj dua P theem rau corrosion tsis kam. Txawm li cas los xij, p txhawb nqa cais tawm hauv cov weld, ua kom muaj kev ntxim nyiam ua rau solidification tawg. Pwht tuaj yeem pab txo qhov no los ntawm kev txhim kho kev nyuaj siab uas tuaj yeem ua rau cov kab mob me me no.
3. Hydrogen tawm tswv yim thaum lub sij hawm vuam
Qhov no yog qhov ua rau muaj kev tawg.
Qhov chaw ntawm hydrogen:Ya dej hauv cov electrodes (yog tias tsis yog ci), damp tej yam kev mob, paug ntawm cov hlau (roj, xeb).
Yog hydrogen yog tam sim no:Pwhly yog ib txoj kev ua tau zoo rau diffuse hydrogen tawm ntawm cov weldrent thiab tiv thaiv ncua qeeb hydrogen {}}), tshwj xeeb yog nyob rau hauv tuab, txwv pob qij txha.
4. Ob leeg txwv thiab tsim qauv
Kev Txwv Siab:Cov pob qij txha ua pob qij txha, pob qij txha, thiab cov ntsuas hluav taws xob tau tsim cov khoom tsim kev ntxhov siab ntawm vuam. PWHT yog feem ntau tsim nyog los tiv thaiv kev nyuaj siab- corrosion tawg los yog qaug zog tsis muaj kev thauj khoom.
Yooj yim, qis {-}} Kev Txwv Cov Pob Qij:Tej zaum yuav tsis xav tau PWHT txawm tias ntawm ntau dua cov thickness, nyob ntawm cov code thiab kev ua haujlwm kev sib koom ua ke.
5. Cov kev pabcuam ib puag ncig thiab daim ntawv thov
Cyclic Chaw thau khoom (qaug zog):Rau choj, crane khiav, lossis cov qauv yuav ua rau kev co thiab nkees, pwht muaj txiaj ntsig zoo heev. Nws relieves peak residual kev ntxhov siab uas tuaj yeem txo qis kev ua kom qaug zog.
Tsawg - kub kev pab:Yog tias tus qauv yuav ua haujlwm hauv huab cua txias, cov khoom siv tawv yog qhov tseem ceeb. PWHT txhim kho haz nruj, txo qhov kev pheej hmoo ntawm brittle bacite bacture thaum kub tsawg.
Cov khoom siv qub hluav taws xob:Rau cov qauv feem ntau nyob rau hauv cov khoom siv qub qub (piv txwv li, kev tsim cov thav duab), qhov xav tau ntawm PWHT yuav raug txo yog tias lwm yam (tuab, hydrogen) yog tswj hwm.
6. Siv tau cov lej thiab cov qauv
Qhov kev txiav txim siab zaum kawg yog feem ntau cov tswj hwm los ntawm kev tswj hwm tsim qauv thiab fabrication code. Piv txwv li:
Aws D1.1 (Vuam cov qauv vuam - hlau):Muaj cov ntxhuav tshwj xeeb, cov ntxhuav kom ntxaws thiab cov cai yuam kev nyob rau ntawm tuab thiab p {}} tus lej ntawm cov khoom.
ASME BOILER THIAB SIAB RAU LUB HLIS CODE:Muaj cov cai nruj yuav tsum yog rau cov hom raws li cov khoom hom thiab tuab.
Qhov tseem ceeb xav rau huab cua hlau: lub patina
Lub ntsiab lus tshwj xeeb rau huab cua hlau yog qhov tsim ntawm nws cov kev tiv thaiv txheej (patina).
Pwht thiab zeb nplai:PWHT feem ntau yog xim tsaus los yog hloov qhov pib mill nplai thiab kev loj hlob patina nyob rau hauv cov chaw sov. Qhov no tuaj yeem ua rau ib ntus tsis yog - cov khaub ncaws tsis zoo.
Ntev - TSHEM KAWG:Qhov no feem ntau tsuas yog luv luv - term cov teeb meem zoo nkauj. Sij hawm dhau los (1-3 xyoos), lub patina yuav ua rau tag nrho cov qauv, thiab cov xim yuav txawm tias yog tus hlau txuas ntxiv rau huab cua tseem ceeb.
