304 vs 304L Stainless Steel Heat Exchanger Tubes: Xaiv thiab Fabrication
Tso lus
Thaum tshav kub kub exchanger tubing ua hauj lwm nyob rau hauv ib tug punishing sib tov ntawm siab, kub thiab corrosive xov xwm, thiab lub raj phab ntsa yog feem ntau thinner tshaj 2 hli. Ob qib austenitic nqa feem ntau ntawm lub plhaub - thiab - raj, condenser, feedwater rhaub thiab cua- cov khoom txias txias: qib classic 18-8304thiab nws qhov qis -carbon tus khub304L. Kev xaiv ntawm lawv tsis tshua muaj lus nug txog lub zog thiab yuav luag txhua lo lus nug ntawm kev coj tus cwj pwm welding, corrosion margin thiab fabrication nqi.
Qhov Ob Qib Tiag Tiag
Ob leeg yog chromium -nickel austenitic stainless hlau. Nyob rau hauv daim ntawv raj lawv ib txwm muab raws li seamless khoom rau ASTM A213 los yog ASME SA-213, raws li welded khoom rau ASTM A249, thiab raws li dav-service raj rau ASTM A269. Lawv cov khoom sib xyaw yog ze li qub; Qhov kev txiav txim siab sib txawv yog carbon, vim hais tias tus cwj pwm ntawm cov pa roj carbon thaum lub sij hawm vuam tswj cov kev ua haujlwm corrosion ntawm cov khoom tiav.
| Parameter | 304 / TSO 304 | 304L / TP 304L |
|---|---|---|
| Carbon, siab tshaj | 0.08 % | 0.030% hauv daim ntawv thiab phaj specifications xws li ASTM A240, 0.035% hauv A213 raj specification |
| Chromium | 18.0-20.0 % | 18.0-20.0 % |
| Nickel | 8.0-11.0 % | 8.0-12.0 % |
| Tsawg tensile zog, ASME SA-213 | 515 MPa ua | 485 MPa ua |
| Yam tsawg kawg nkaus yield zog, ASME SA-213 | 205 MPa | 170 MPa |
| Thermal conductivity nyob ze ntawm chav tsev kub | Txog 16 W / (m·K) | Txog 16 W / (m·K) |
| Intergranular corrosion kuj zoo li welded | Txais tau hauv cov phab ntsa nyias thaum tswj cov cua sov | Zoo heev yam tsis muaj kev tshaj tawm -weld tov annealing |
| Kev kub kub xws li stamping, dabtsi yog khoov thiab U-bending | Zoo; hardens los ntawm kev ua haujlwm txias xwb | Zoo; me ntsis softer thiab ntau zam txim |
| Cov kev pabcuam | Chav, condensate, dej txias, qis - chloride txheej txheem ntws | Welded bundles ntxiv loj - txoj kab uas hla thiab hnyav - phab ntsa tubing |
Thermal Performance: Ze li ib khi
Lub raj xa hluav taws xob muaj nyob kom txav cua sov hla ntawm phab ntsa nyias, yog li thermal conductivity yog thawj qhov kev tshuaj ntsuam xyuas. Austenitic stainless hlau ua cua sov ntawm ib feem me me ntawm tus nqi ntawm tooj liab alloys, kwv yees li 16 W / (m·K) nyob ze ntawm chav tsev kub rau ob qib, thiab 304 thiab 304L yog qhov sib txawv ntawm qhov ntsuas no. Qhov kev ua tau zoo tiag tiag tshwm sim rau lwm qhov: phab ntsa thickness, bore tiav, ovality thiab kev huv ntawm cov txheej txheem sab. Ib tug du, dimensionally zoo ib yam bore resists fouling, thiab ib tug fouling txheej nqi ntau dua tshav kub hloov dua siab tshiab conductivity sib txawv ntawm ob qib austenitic. U-khoov seem yuav tsum tau tsim yam tsis muaj phab ntsa ntau dhau ntawm qhov khoov sab nraud, vim tias lub hau nyias nyias ua qhov kub tshaj plaws thiab tsis muaj zog ntawm lub raj.
Fabrication thiab Vuam Cwj Pwm
Thaum tshav kub kub exchanger raj xav tau los ua cov txheej txheem: kev tswj qhov seem ntawm lub raj - mus rau -tubesheet sib koom ua ke, kev nthuav dav lossis vuam ntawm ntau txhiab pob qij txha thiab kev huv huv hauv lub bore tag nrho cov teeb meem, thiab ib qho kev sib koom ua ke tsis zoo cuam tshuam rau tag nrho chav tsev. Qib 304 teb zoo rau kev ua haujlwm kub xws li stamping thiab dabtsi yog khoov, hardens nkaus xwb los ntawm kev ua haujlwm txias, thiab yog li tsis tas yuav hardening kev kho cua sov. Thaum 304 tuav nyob rau hauv 450-850℃sensitization ntau yam thaum lub sij hawm vuam, chromium carbides tuaj yeem ua rau ntawm cov ciam teb nplej thiab deplete cov hlau uas nyob ib sab ntawm chromium, ua rau nws qhib rau intergranular nres hauv tshav kub- cuam tshuam cheeb tsam. Tsawg-carbon 304L tshem tawm cov txheej txheem ntawd. Tom qab vuam los yog kev ntxhov siab, 304L khaws nws cov intergranular corrosion kuj yam tsis muaj kev daws teeb meem tag nrho, thiab nws cov ntsiab lus qis dua kuj tseem ua rau nws zoo dua rau thermal shock dua 304, uas ua rau cov pob khoom ruaj khov thiab txhim khu kev qha los ntawm kev rov pib dua thiab kaw lub voj voog.
Kev taw qhia kev xaiv rau cov neeg yuav khoom
Xaiv 304Thaum lub raj yog seamless, phab ntsa yog nyias, welding yog txwv rau cov tubesheet sib koom ua ke thiab cov kwj deg yog dej, chav dej los yog cov dej uas muaj chloride tsawg.
Xaiv 304Lthaum lub raj yog welded tom qab tsim, thaum lub phab ntsa hnyav los yog txoj kab uas hla loj, los yog thaum nyob rau hauv - kev pab cuam kev ntxhov siab yog xav txog.
Tsis txhob kho 304L raws li kev txhim kho corrosion.Nyob qhov twg muaj cov tshuaj chlorides, txo cov kua qaub los yog pitting lub luag hauj lwm, molybdenum -cov kabmob qib xws li 316L yog qhov tseeb.
Kho cov specification ua ntej hais.Lub xeev qib, qhov ntev, chav kawm kam rau ua, kev xa khoom, kev sim siab thiab kev tswj hwm tus txheej txheem kom muaj peev xwm muab piv rau cov lus sib npaug.
Kev Tshawb Fawb Tuaj Uas Them Rau Nws Tus Kheej
Qib twg raug txiav txim, qhov tau txais kev tshuaj xyuas niaj hnub rau cov raj xa dej yuav tsum npog qhov ntsuas qhov ntsuas sab nraud ntawm txoj kab uas hla thiab phab ntsa tuab, ntsuas hydrostatic lossis pneumatic, eddy-tam sim no lossis ultrasonic kuaj ntawm lub raj lub cev, flattening thiab flaring test, thiab tensile lossis hardness verification ntawm tus qauv. Intergranular corrosion testing rau qhov kev coj ua tau ntxiv thaum qhov kev pabcuam xav tau cov ntaub ntawv pov thawj corrosion. Thaum tshav kub kub-tus naj npawb-rau- pob traceability yog tus txheej txheem kev coj ua rau refinery, petrochemical thiab fais fab kev yuav khoom, thiab nws yog tib txoj hauv kev los kaw qhov kev tshawb nrhiav tsis ua haujlwm sai.
Cov lus nug nquag
Q: Qib twg yog qhov zoo dua rau cov raj xa hluav taws xob, 304 lossis 304L?
Tsis yog universally zoo dua . 304L suits welded bundles thiab hnyav dua vim hais tias cov ntsiab lus carbon tsawg tiv thaiv rhiab heev, thaum 304 yog kiag li haum rau seamless nyias- phab ntsa tubing nyob rau hauv dej huv thiab chav dej.
Q: Puas yog 304L tsis muaj zog dua li 304?
Me ntsis. ASME SA-213 teeb tsa lub zog tensile yam tsawg kawg nkaus ntawm 515 MPa rau TP304 tiv thaiv 485 MPa rau TP304L, thiab lub zog qis kawg nkaus ntawm 205 MPa tiv thaiv 170 MPa. Kev tsim kev suav yuav tsum siv qhov tseem ceeb ntawm qib uas tau txiav txim.
Q: Puas yog 304 raj xav tau kev kho cua sov tom qab khoov?
Feem ntau tsis yog. Qib 304 tsis tawv los ntawm kev kho cua sov thiab tsis muaj zog los ntawm nws, yog li U- khoov thiab txias zoo sib xws- cov seem tau muab rau hauv qhov txias- ua haujlwm, nrog kev ntxhov siab- nyem annealing tsuas yog thaum qhov kev yuav khoom tshwj xeeb xav tau.
Q: Puas yog 304 thiab 304L tuaj yeem txuas rau ib leeg?
Yog lawm. Ob qib yog austenitic thiab metallurgically sib xws. Sib piv los yog me ntsis dhau -alloyed austenitic muab tub lim feem ntau yog siv, thiab tshav kub- cuam tshuam thaj tsam ntawm 304 sab coj ua qis dua -carbon, yooj yim weldable cheeb tsam.
Q: Vim li cas 304L tiv thaiv intergranular corrosion tom qab vuam?
Nrog cov pa roj carbon tuav hauv qab ntawm qib uas chromium carbides tuaj yeem ua rau ntawm qhov ntsuas qhov ua tau zoo, chromium depletion ntawm cov ciam teb yog txwv, yog li cov cua sov- cuam tshuam thaj tsam khaws nws cov corrosion tsis kam tom qab -weld solution annealing.
Q: Cov qauv twg npog stainless hlau tshav kub exchanger raj?
Seamless austenitic exchanger thiab boiler raj yog them los ntawm ASTM A213 / ASME SA-213, welded raj los ntawm ASTM A249 thiab dav dav corrosion-resistant service tube los ntawm ASTM A269. Daim ntawv qhia meej thiab txhua qhov kev xav tau ntxiv yuav tsum tau hais hauv qhov kev nug.
