What Material to Use for Valves in High Temperature Condition

High temperature conditions include sub-high temperature, high temperature grade Ⅰ, high temperature class Ⅱ, high temperature grade Ⅲ, high temperature Ⅳ grade, high temperature Ⅴ grade, the following were introduced.

1, sub-high temperature

Sub-high temperature refers to the valve operating temperature in the 325 ~ 425 ℃ area. If the medium is water and steam, mainly with WCB, WCC, A105, WC6 and WC9. If the medium is sulfur-containing oil, mainly with anti-sulfide corrosion of C5, CF8, CF3, CF8M and CF3M and so on. They are used in oil refinery often decompression device and delayed coking device, then CF8, CF8M, CF3 and CF3M material of the valve is not used for acid solution corrosion, but for sulfur oil and oil and gas pipelines. In this case, the maximum operating temperature of CF8, CF8M, CF3 and CF3M is 450 ℃.

2, high temperature class Ⅰ

Valve operating temperature of 425 ~ 550 ℃ for the high temperature class Ⅰ (referred to as PI level). PI-class valve body material for the ASTMA351 standard CF8 for the base of the "high temperature grade Ⅰ in the carbon chromium nickel rare earth titanium high-quality heat-resistant steel." Because PI grade is a specific name, here contains the concept of high temperature stainless steel (P). Therefore, if the working medium is water or steam, although high temperature steel WC6 (t≤540C) or WC9 (t? 570C) may be used, high temperature steel C5 (ZG1Cr5Mo) may be used in sulfur-containing oil, It can not be called PI here.

3, high temperature class Ⅱ

Valve operating temperature of 550 ~ 650 ℃, as high temperature class Ⅱ (referred to as P Ⅱ level). P-class high-temperature valve is mainly used for refinery heavy oil catalytic cracking unit, which contains the use of three spin nozzles and other parts of the high temperature lining wear valve. P Ⅱ grade valve body material for the ASTMA351 standard CF8 as the base of the "high temperature Ⅱ grade carbon chromium nickel rare earth titanium tantalum reinforced heat-resistant steel."

4, high temperature grade Ⅲ

Valve operating temperature of 650 ~ 730 ℃, as high temperature Ⅲ (referred to as P Ⅲ level). P Ⅲ grade high temperature valve is mainly used in the refinery large heavy oil catalytic cracking unit. P Ⅲ grade high temperature valve body material for the ASTMA351 standard CF8M for the base of the "high temperature Ⅲ grade carbon chromium nickel molybdenum rare earth titanium tantalum reinforced heat-resistant steel."

5, high temperature Ⅳ level

Valve operating temperature of 730 ~ 816 ℃, set high temperature Ⅳ (referred to as P Ⅳ level). The upper limit of the operating temperature of the P IV grade valve is set at 816 ° C because the maximum temperature provided in the standard ASMEB16134 pressure-temperature class for the valve design is 816 ° C (1500 ° V). In addition, the working temperature of more than 816 ℃, the steel is close to the forging temperature into the region, when the metal is in plastic deformation interval, the plasticity of the metal is good, difficult to bear high working pressure and impact and remain unchanged. P Ⅳ grade valve body material for the ASTMA351 standard CF8M for the base "high temperature Ⅳ grade carbon chromium nickel molybdenum rare earth titanium tantalum reinforced heat-resistant steel." CK-20 and ASTMA182 standard F310 (including C content ≥101050%) and F310H and other heat-resistant stainless steel.