The high temperature grades of high temperature valves are divided into five levels, namely, the valve working temperature t>425~550℃ is PI grade, the working temperature t>550~650℃ is PII grade, the working temperature t>650~730℃ is PⅢ grade, the working temperature t>730~816℃ is PⅣ grade, and the working temperature t>816 degree yog PV qib. Cov ntaub ntawv tseem ceeb ntawm PI thiab PⅡ qib siab kub li qub tuaj yeem xaiv los ntawm cov hlau tsis muaj cua sov xws li ZG0Cr19Ni11Ti, ZG1Cr18Ni9Ti, 321 thiab 321H lossis CF8, 304 thiab 304H. Yog tias PI qib siab kub valve siv rau dej thiab chav dej, WC6 thiab WC9 tuaj yeem xaiv. Yog tias qhov nruab nrab yog dej, chav thiab roj, CS (ZG1Cr5Mo) thiab lwm yam Cr-Mo siab kub hlau tuaj yeem xaiv. CFSM, 316 thiab 316H stainless hlau kub-resistant steels tuaj yeem xaiv rau qib PⅢ thiab PⅣ. PIV qib kuj tuaj yeem siv CK-20, 310 thiab 310H siab chromium nickel stainless hlau kub-resistant. PV qib siab kub li qub tuaj yeem xaiv cov khoom tsim nyog uas tuaj yeem ua tau raws li kev siv lub valve raws li nws qhov nruab nrab ua haujlwm, kev ua haujlwm siab thiab cov qauv tsim tshwj xeeb tau txais. Txawm li cas los xij, Cr-Mo kub-resistant steel siv nyob rau hauv high kub li qub yuav tsum tau smelted nyob rau hauv ib tug hluav taws xob arc rauv thiab ib tug kub resistant smelting txheej txheem yuav tsum tau siv.
