“The cast steel gate valve is a stainless steel gate valve” is not accurate. This statement is only a one-sided understanding of the two valves. In fact, there is still a big difference between the two. Cast steel gate valves refer to all gate valves that are cast into metal castings and cast into castings. These gate valves are collectively referred to as cast steel gate valves. It can be divided into: carbon steel gate valve, stainless steel gate valve, low alloy steel gate valve (high temperature resistant chrome molybdenum steel category), low temperature steel gate valve, etc. Corresponding to the cast steel gate valve, it also has a cast iron gate valve, a forged steel gate valve, and a malleable cast iron gate valve.
It is believed that we can see at this time that the cast steel gate valve and the stainless steel gate valve are actually a molding method, that is, a process, and the other is a material type. The cast steel gate valve may be a stainless steel gate valve, or a carbon steel gate valve or an alloy steel gate valve. Stainless steel gate valves are stainless steel valves that can be either cast or forged. From the scope of view: cast steel ≥ stainless steel valve.
All kinds of cast steel gate valves have different steel grades, which will be printed on the valve body. The commonly used grades are as follows:
1. Carbon steel gate valve casting grades are: WCA, WCB, WCC, LCB, etc.; applicable temperature -46 degrees ~ 425 degrees.
2. Stainless steel gate valve casting grade: 301 stainless steel, CF8 stainless steel (corresponding to forging 304 stainless steel), CF8M stainless steel (corresponding to forging 316 stainless steel), etc.; applicable temperature -198 degrees ~ 816 degrees.
3. Low-alloy steel is divided into high-temperature alloy steel and high-strength low-alloy steel, among which high-temperature alloy steel is commonly known as chrome-molybdenum steel. Casting grades of chrome-molybdenum steel gate valves: ZG1Cr5Mo, ZG15Cr1MoV, ZG20CrMoV, WC6, WC9, C12A, etc. Applicable temperature 550 degrees to 750 degrees.
The temperature at which each specific grade material is applied varies. It should be selected according to the actual working conditions.
It is worth mentioning here that cast steel gate valves and forged steel gate valves are often confused because of their similar names, and people do not know how to choose. In fact, the direct distinguishing method is to look at the material grade. For example, the casting grade of 304 stainless steel is generally indicated as CF3 or CF8, and the forging is generally marked as 06Cr19Ni10 or directly labeled 304. As for the choice of cast steel gate valve or forged steel gate valve, it is mainly determined by the working conditions. When the medium condition is special, the forged steel gate valve is mainly used, because the forged steel gate valve is more mature in the process, and many domestic manufacturers can do it. It is also possible to refer to the general reference from the caliber. Generally, the forged gate valve is selected when the number is below DN40. When the caliber is above DN40, the casting gate valve is selected. The pressure with a small caliber relative to a small diameter will be smaller. But of course, we must actively consider the actual requirements of our customers. Manufacturers can give some reasonable advice.