Dab tsi A790 Pipe yog ua los ntawm
ASTM A790 yog tus qauv tshwj xeeb rau seamless thiab welded ferritic -austenitic (duplex) stainless hlau yeeb nkab rau kev pabcuam corrosive. Cov khoom siv tsev neeg yog duplex stainless hlau: ib qho microstructure ntawm kwv yees li 50% ferrite thiab 50% austenite, sib npaug los ntawm cov alloy muaj pes tsawg leeg thiab cov cua sov- kho lub voj voog. Qhov ob-theem qauv muab cov hlau txog ob npaug ntawm cov khoom muaj zog ntawm cov qib austenitic xws li 316L, ua ke nrog kev ua haujlwm zoo heev rau chloride kev nyuaj siab corrosion cracking, pitting, thiab crevice corrosion. Duplex yeeb nkab yog tus qauv kev xaiv rau seawater systems, offshore platforms, tshuaj ua, thiab lwm yam chloride{10}}nplua nuj ib puag ncig.
Cov Qib Siab
A790 txhais cov chemistry ntawm cov qib los ntawm lawv cov lej UNS. Cov qib pauv feem ntau yog:
| Qib | Tsev neeg | Yam tsawg kawg nkaus yield zog |
|---|---|---|
| S31803 | Txheem duplex (22 Cr) | 450 MPa |
| S32205 | Standard duplex (22 Cr, nruj) | 450 MPa |
| S32304 | Lean duplex (23 Cr) | 400 MPa |
| S32750 | Super duplex (25 Cr) | 550 MPa |
| S32760 | Super duplex (25 Cr) | 550 MPa |
S31803 thiab S32205 yog ob qho tib si muag li 2205 duplex; S32205 muaj nruj dua nitrogen thiab muaj pes tsawg leeg tswj thiab yog lub neej niaj hnub. Lub super-duplex qib S32750 thiab S32760 ntxiv chromium, molybdenum, thiab nitrogen, nrog lub zog ntau dua thiab ntau dua pitting kuj sib npaug (PREN), rau cov kev pabcuam chloride tshaj plaws xws li cov dej hiav txwv thiab kev ua haujlwm desalination.
Kev sib xyaw thiab cov khoom
Cov muaj pes tsawg leeg ntawm 2205 duplex (S32205) yog hais txog 22% chromium, 5% npib tsib xee, 3.2% molybdenum, thiab 0.17% nitrogen, nrog carbon txwv rau 0.03%. Qhov tsawg kawg nkaus txhua yam khoom ntawm A790 yog lub zog tawm ntawm 450 MPa, lub zog tensile ntawm 655 MPa, thiab qhov tsawg kawg nkaus elongation ntawm 25%. Cov qib super-duplex qib ncav cuag yam tsawg kawg nkaus ntawm 550 MPa nrog tensile zog siab tshaj 750 MPa. Cov khoom yog muab rau hauv cov tshuaj-annealed mob, ib txwm nyob ntawm 1020 txog 1100 C nyob ntawm qib, ua raws li kev ua kom txias sai kom khaws cov theem kom raug.
A790 Tubing vs A789 Tubing
A790 npog duplex yeeb nkab, tsim los ntawm nominal yeeb nkab loj thiab lub sij hawm, siv rau siab thiab mechanical kev pab cuam. A789 npog duplex tubing, tsim los ntawm sab nraud txoj kab uas hla thiab phab ntsa tuab, siv rau cov cua sov-exchanger thiab condenser raj thiab kev pabcuam dav dav. Cov ntaub ntawv qib yog tib yam; qhov sib txawv yog cov khoom tsim, qhov loj me, thiab daim ntawv thov npaj. Ob qho qauv siv nyob rau hauv tib lub lag luam, thiab qhov project kos duab hais tias yuav tsum muaj daim ntawv twg.
A790 vs A312 Austenitic Pipe
A312 npog austenitic stainless hlau yeeb nkab xws li TP304L thiab TP316L. Piv nrog rau cov no, cov yeeb nkab duplex muaj zog dua, zoo dua tiv thaiv chloride kev nyuaj siab corrosion cracking, thiab sib piv los yog zoo pitting tsis kam ntawm tus nqi qis dua li cov qib austenitic siab dua. Kev lag luam tawm -tawm yog nyob rau hauv fabricability: duplex yuav tsum nruj me ntsis tswj ntawm vuam cua sov input, interpass kub, thiab muab tub lim xaiv los tswj cov theem sib npaug ntawm weld, thiab muab tub lim hlau feem ntau yog siab dua -alloy duplex qib.
Cast thiab Wrought Equivalents
Rau cov khoom cam khwb cia, duplex casting qib A995 Qib 4A sib raug rau tsev neeg wrought 2205 duplex (S31803 / S32205). Lub valve lossis fitting cam khwb cia rau A995 4A muaj qhov zoo sib xws ntawm corrosion thiab mechanical zog rau cov yeeb nkab ua rau A790 los ntawm 2205. Qhov kev sib koom ua ke no tso cai rau cov tshuab ua kom tiav nrog cov ntaub ntawv duplex zoo ib yam, thiab tib qhov vuam thiab cua sov- kev qhuab qhia kev kho mob siv rau ob hom khoom.
Cov lus nug nquag
Q: ASTM A790 yeeb nkab yog dab tsi?
Duplex stainless hlau, ferritic - austenitic alloy nrog kwv yees li 50% ferrite thiab 50% austenite, muab lub zog siab thiab zoo heev tiv thaiv chloride kev nyuaj siab corrosion cracking.
Q: Cov qib twg muaj nyob rau hauv A790?
Lean duplex S32304, standard duplex S31803 thiab S32205 (2205), thiab super-duplex S32750 thiab S32760, thiab lwm yam.
Q: Qhov txawv ntawm A790 thiab A789 yog dab tsi?
A790 npog duplex yeeb nkab rau siab thiab kho tshuab; A789 npog duplex tubing rau cua sov exchangers thiab condensers. Cov qhab nia zoo ib yam, cov ntaub ntawv khoom sib txawv.
Q: Lub zog tawm ntawm 2205 duplex yeeb nkab yog dab tsi?
Qhov tsawg kawg nkaus yield zog yog 450 MPa thiab qhov tsawg kawg nkaus tensile lub zog yog 655 MPa, nrog rau qhov tsawg kawg nkaus elongation ntawm 25%.
Q: Puas yog A995 Qib 4A sib npaug rau 2205?
Yog lawm. A995 Qib 4A yog cov cam khwb cia duplex qib sib haum rau cov wrought S31803 / S32205 tsev neeg siv hauv A790 yeeb nkab.
Q: Duplex yeeb nkab puas tuaj yeem welded?
Yog lawm, nrog kev tswj cov cua sov, qhov siab tshaj plaws interpass kub, thiab sib txuam lossis dhau - alloyed duplex muab tub lim hlau. Lub vuam yuav tsum raug txheeb xyuas rau theem sib npaug kom khaws cov corrosion kuj.
