Valve pressure and temperature rating
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Ball Valve Certificate of Conformity: Product name: Ball valve; Model: J61Y-40; Nominal diameter: DN50; Nominal pressure: 4.0 MPa; Applicable temperature: ≤425°C; Applicable medium: Steam; License number: TS***; Inspector: Inspection No. 02; Date of manufacture: 20190603. Can the ball valve mentioned above be used in steam pipelines with a design pressure of 4.0 MPa and a design temperature of 425°C? Thank you. Please provide the reasons; mainly, I am not familiar with the standards for valve pressure and temperature ratings.
Could you provide the actual operating pressure (the pressure difference when the valve is closed, or the pressure difference before and after the valve) as well as the actual temperature of the pipeline?
Obviously not; your valve is of PN40 grade, and the manual states that the applicable temperature is 425°C, but the pressure at 425°C is not 4.0 MPa. Your valve is a standard carbon steel valve, with a suitable pressure at 425°C of around 2.1 MPa.
Obviously not. The parameters of your valve do not mean that all of them need to be satisfied simultaneously; rather, the maximum value that a particular parameter can reach is indicated. For example, a nominal pressure of 4.0 MPa means that the valve is suitable for a pressure rating of PN40 and can operate at temperatures up to 425 degrees. This indicates that the valve has been selected based on temperature and pressure criteria, and it can meet the requirements at 425 degrees under a certain pressure. However, the pressure corresponding to 425 degrees is not necessarily 4.0 MPa – it’s more likely to be lower than that value.
It’s smashed online without leaving any room at all? Isn’t that a bit too stingy? You managed to set this up on your own too – I really admire that. It’s better to leave some room for yourself; otherwise, it won’t be fun. If you work in design, you also need to leave some margin for design, right?
If the actual operation is close to the design parameters, such a choice is indeed a bit arbitrary; to ensure safety, it is recommended to use valves of a higher grade.
The pressure and temperature ratings specified in the flange standard HG20592 can be used as a reference; note that this refers to the operating temperature.
Absolutely not; with a nominal pressure of 40, its pressure resistance at 425 degrees is much lower
The working pressure and working temperature cannot both reach their maximum limits at the same time
It’s best not to use it; it’s better to leave some margin! It’s impossible to have no margin at all! That’s not safe!
Firstly, looking solely at the nominal pressure value, there is no problem; however, when considering the applicable temperature, it is clearly not feasible. The operating temperature you specified already represents the upper limit for using this valve. It is recommended to use materials with high temperature resistance. The original poster can refer to the pressure-temperature rating table in standard GB/T 12224 to determine the appropriate material for these conditions