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Application of alloy pipes in power station boilers

Application of alloy steel pipes in heat-resistant steel for power station boilers

What is the meaning of heat-resistant steel pipes in power stations?

The meaning of heat-resistant steel pipes in power plants includes the two comprehensive concepts of resisting pipe oxidation under high-temperature conditions and possessing high-temperature strength.

When there are enough Cr, Al, Si and other elements in the chemical composition of the steel pipe, when the outside of the steel is affected by oxygen at high temperature, a layer of oxide film will be densely covered to prevent the steel from continuing to oxidize and corrode. If the steel has 9% Cr content, the oxidation resistance temperature can reach 620 ℃. High temperature strength is to participate in the recrystallization temperature of Ni, N, Cu and other elements to enhance the ability of steel to resist creep.

Application of alloy steel pipes in heat-resistant steel for power station boilers

The steam parameters of power station boilers have been increased from 538 ° C to 566 ° C, as long as the low- and medium-alloy Cr-Mo and Cr-Mo-V steels are fully utilized, such as the low-alloy boiler steel tubes that have been in use, such as 1.25% Cr-0.5% Mo (SA213 -T11), 2.25% Cr-1% Mo (SA213-T22) and 9-12% Cr series of Cr-Mo and Cr-Mo-V steels such as T91 (SA213-T91) can be achieved, or improved 9% -12% Cr steel to improve unit reliability. The primary development of high-steam parameter heat-resistant steel for gensets focused on increasing the steam parameters from 566 ° C to 593 ° C. This increase in temperature can be achieved by using improved ferritic steel to ensure the operational flexibility of existing units achieve. Such as the change of T92 (SA213-T92) and so on.

Development trend of alloy steel tubes for power station boilers:

1. Supercritical power generation boilers have adopted SA213-T91 / SA335-P92 as the most promising commercial material for high temperature, and partially replaced the austenitic stainless steels SA213-TP304H and TP347H;

2. For ferritic steels, mainly to improve the material's creep fracture strength, for austenitic steels, to reduce costs and improve the resistance to steam oxidation and thermal corrosion, such as SUPER304H based on SA213-TP304H