Industry News
High Temperature Working Conditions of Valves (Part One)
Posted: 08/11/2017 12:40:58  Hits: 17
High Temperature Working Conditions
Valves used for the high temperature working conditions mainly refer to the high temperature valves applied to the refineries.
Sub-high Temperature
Sub-high temperatures refer to the working temperatures of valves between 325℃ and 425℃. When the medium is water or steam, the valves are usually made of materials WCB, WCC, A105, WC6 and WC9. If the medium is the sour crude oil, the valves are supposed to be made of the materials C5, CF8, CF3, CF8M, CF3M, etc. These materials are resistant to the corrosion of the sulfide. These valves are generally used for the crude units and delayed coker units of refineries. The valves made of materials CF8, CF8M, CF3 and CF3M are commonly used for the pipelines transporting sour crude oil, oil and natural gas instead of the acid solution. Under this working condition, the maximum working temperature of materials CF8, CF8M, CF3 and CF3M is 450℃.
High-temperature Grade I
High-temperature Grade I valves, also known as high-temperature PI Grade valves, refers to the valves whose working temperatures are between 425℃ and 550℃.

The main material of the PI Grade valve is the top quality high temperature GradeⅠheat-resistant steel containing carbon, chromium, nickel and rare earth titanium, which is based on CF8 in ASTM A351 standard. PI Grade is a specific name, and the capital letter "P" represents the concept of high temperature stainless steel. Therefore, although the valves for transporting the media such as water and steam are made of high-temperature steel WC6(t≤540℃) or WC9(t≤570℃), and the the valves for transporting sour crude oil are made of high-temperature steel C5(ZG1Cr5Mo), they can not be called the PI Grade valves.
High-temperature Grade II
When working temperatures of valves are between 425℃ and 650℃, the valves are called the high-temperature Grade II valves, also named the high-temperature PII Grade valves. They are mainly used for the heavy oil catalytic cracking units of refineries. High-temperature PII Grade valves contain the wear resistant lining high-temperature gate valves used for the three spin nozzles and other parts. The main material of the PII Grade valve is the strengthening high temperature Grade II heat-resistant steel containing carbon, chromium, nickel and rare earth titanium, which is based on CF8 in ASTM A351 standard.