Cov ntsiab lus tseem ceeb: ASTM A178 yog dab tsi?
ASTM A178 yog ib qho kev qhia tshwj xeeb los ntawm ASTM International rauhluav taws xob-kuj-welded (ERW) carbon steel thiab carbon-manganese steel boiler raj thiab superheater raj. Qhov tseem ceeb ntawm kev tshem tawm yog tias cov kav dej / raj no yog tsim los rau siab - kev pabcuam siab hauv boilers thiab cov khoom siv hluav taws xob.
Cov yam ntxwv tseem ceeb thiab kev siv
Kev Siv Tseem Ceeb:Boiler tubes, superheater tubes, thiab tshav kub exchanger raj nyob rau hauv chaw nres tsheb boilers, nkoj, thiab locomotives.
Kev tsim khoom: Electric Resistance Vuam (ERW). Cov txheej txheem no tsim kom huv si, muaj zog weld los ntawm kev hla hluav taws xob los ntawm cov khoom siv.
Kev Pabcuam:Tsim los rau siab - kev pabcuam siab. Lawv tuaj yeem siv rau hauv qhov cub thiab qhov twg lub raj yog sab nraud rhuab.
Qhov ntau thiab tsawg:Feem ntau npog cov hlab nrog lub cheeb sab nraud txog li 5 ntiv tes (127 hli).
Qib A178 Pipe
Tus qauv qhia ob qib tseem ceeb, sib txawv los ntawm lawv cov tshuaj muaj pes tsawg leeg thiab lub zog txhua yam.
| Qib | Kev piav qhia | Cov yam ntxwv tseem ceeb & Kev siv yooj yim |
|---|---|---|
| Qib A | Carbon Steel | Tsawg zog.Qib feem ntau rau kev siv boiler dav dav, xws li cov raj dej boilers. |
| Qib D | Carbon-Manganese hlau | Siab zog.Muaj Manganese thiab Silicon ntau dua qib A, uas ua rau muaj zog tensile thiab yield zog. Siv rau superheater raj thiab lwm yam siab - kev siv kev ntxhov siab. |
Chemical Composition (Qhov hnyav%)
Cov tshuaj muaj pes tsawg leeg yog nruj tswj hwm los xyuas kom meej weldability thiab kev ua tau zoo.
| Lub ntsiab | Qib A | Qib D |
|---|---|---|
| Cov pa roj carbon, max | 0.18% | 0.27% |
| Manganese | 0.27 - 0.63% | 0.29 - 0.95% |
| Phosphorus, max | 0.035% | 0.035% |
| Sulfur, max | 0.035% | 0.035% |
| Silicon, min | - | 0.10% |
Lus Cim: Qib D qhov siab dua Manganese thiab qhov yuav tsum tau muaj rau Silicon muab nws lub zog ntau dua.
Mechanical Properties
Qhov no yog qhov tseem ceeb sib txawv ntawm cov qib.
| Khoom | Qib A | Qib D |
|---|---|---|
| Tensile zog, min | 47 ksi (325 MPa) | 60 ksi (415 MPa) |
| Yield zog, min | 26 ksi (180 MPa) | 37 ksi (255 MPa) |
| Elongation, min | 35% (hauv 2 nti) | 30% (hauv 2 nti) |
Kev kuaj thiab tshuaj xyuas yuav tsum tau ua
A178 cov raj muaj kev tswj xyuas nruj kom ntseeg tau tias muaj kev nyab xeeb thiab kev ntseeg siab nyob rau hauv siab - ib puag ncig siab. Cov kev ntsuam xyuas tseem ceeb suav nrog:
Flattening Test:Ib qho piv txwv ntawm lub raj yog flattened mus rau ib qho kev ncua deb los xyuas lub suab ntawm lub vuam thiab ductility ntawm lub hauv paus hlau.
Flange Test:Qhov kawg ntawm lub raj yog flared tawm mus rau ib txoj kab uas hla kom pom nws cov ductility.
Hydrostatic Test:Txhua lub raj raug sim rau qhov dej siab kom ntseeg tau tias nws tuaj yeem tuav lub siab yam tsis muaj dej. (Tsis yog-kev kuaj kev puas tsuaj).
Nondestructive Electric Test:Lub weld seam yog tshuaj xyuas siv lub eddy tam sim no los yog ultrasonic kuaj los xyuas seb puas muaj qhov tsis xws luag. Qhov no yog qhov xav tau tseem ceeb rau ERW raj.
Reverse Bend Test (rau Qib A):Ib qho kev ntsuam xyuas tshwj xeeb uas ib daim kab xev uas muaj cov vuam yog khoov rov qab los xyuas qhov zoo ntawm qhov vuam.
Tensile Test & Hardness Test:Txhawm rau txheeb xyuas cov khoom siv kho tshuab.
A178 vs. Lwm Hom Boiler Tube Standards
Nws muaj txiaj ntsig zoo piv A178 rau lwm cov qauv zoo sib xws:
ASTM A178 vs ASTM A192 Cov Lus Qhia:
A178yog rauERWcov raj.
A192yog rauSeamlesscov raj. A192 feem ntau yog siv rau siab - siab boiler daim ntaub ntawv qhov twg seamless tsim yog nyiam rau cov kev pab cuam tseem ceeb tshaj plaws. A192 muaj cov ntsiab lus qis dua, ua rau nws zoo heev.
ASTM A178 thiab ASTM A53:
A178yog tshwj xeeb rauboiler thiab tshav kub exchangerkev pabcuam (siab-siab, siab-kub).
A53yog tus qauv dav dav raustructural thiab mechanicalcev. Nws tsis yog siv rau hauv boilers los yog nyob rau hauv tib theem ntawm kev soj ntsuam raws li A178. A53 tuaj yeem yog ERW lossis seamless.
ASTM A178 thiab ASTM A106:
A106yog rauseamlesscarbon steel yeeb nkab rau siab - qhov kev pab kub (xws li txheej txheem piping hauv refineries). Nws tsis yog tshwj xeeb yog tus qauv boiler raj tab sis yog siv rau cov kev pabcuam kub zoo sib xws.
Summary thiab Key Takeaways
Lub hom phiaj-Ua:ASTM A178 tsis yog qhov dav dav - lub hom phiaj yeeb nkab. Nws yog tshwj xeeb engineered rau boiler thiab tshav kub exchanger daim ntaub ntawv.
ERW txheej txheem:Txhua lub raj A178 yog hluav taws xob-kuj-welded.
Ob Qib Main: Qib Arau lub luag haujlwm dav dav,Qib Drau siab zog (superheaters).
Kev sim nruj:Ua raws li kev sib tw, flaring, hydrostatic, thiab nondestructive tests kom ntseeg tau tias kev ncaj ncees nyob rau hauv siab.
Tsis siv neeg siv:Tsis txhob hloov cov yeeb nkab A178 rau cov kav dej lossis cov yeeb nkab (zoo li A53); nws yog ib qho khoom tshwj xeeb rau kev siv tseem ceeb.
Thaum muab A178 yeeb nkab, nws yog ib qho tseem ceeb heev rau kev ua hauj lwm nrog ib tug reputable tsum uas muaj peev xwm muab cov yuav tsum tau Mill Test Certificate (MTRs) los xyuas kom meej tias cov khoom ua tau raws li tag nrho cov tshuaj thiab mechanical xav tau ntawm tus qauv.
