Question: What is the relationship between the pressure rating of pipeline design and the pressure rating of valves? Do they have to be identical?
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I have a design: the pipeline is designed for a pressure of 4.2 Mpa and a temperature of 200 degrees; the flange pressure class is CL.600； However, for various reasons, the valve pressure rating chosen is (CL.300). In the piping field, it is considered that pipes rated (CL.600) cannot be used with valves rated (CL.300), which prevents the piping work from being completed. Question: What is the relationship between the pressure rating of pipeline design and the pressure rating of valves? Do they have to be identical?
It should be consistent; otherwise, ask the valve manufacturer to provide matching flanges
Valve pressure rating (after temperature correction) >= Pipeline design pressure rating (after temperature correction)
Agree with the second floor. But in my personal opinion, at 4.2 MPa and 200 degrees, using a valve with a pressure rating of 300 pounds seems a bit excessive. If a 300-pound valve can indeed be used, 300-pound flanges can be used at the points where it is connected to other components, while 600-pound flanges can be used elsewhere. But if a 300-pound valve is acceptable, why use a 600-pound grade? It's fine to use 300 pounds for everything.
The pressure rating of the valve must be equal to or higher than that of the pipeline; otherwise, the valve cannot be used.
The pressure rating of the pipeline design should be the same as that of the valves.
The pressure rating of the valve must be greater than or equal to that of the pipeline
300 pounds saves a lot of money. . Your MR documents must state 600 pounds; otherwise, it will be your responsibility.
Yes, the valve rating must be equal to or higher than that of the pipeline. However, CL300 is equivalent to 5.0 MPa, so it seems similar. Imported valves should be fine for this purpose, but it’s hard to say the same for domestically produced valves
The pressure rating of valves and fittings must be at least as high as that of the pipeline. It’s definitely not acceptable to use CLASS 600 valves for pipelines of that class; the piping specialists will refuse to install them out of concern for your safety. Otherwise, you’ll be the one to face the consequences if anything goes wrong. Don’t fall for the nonsense told by valve manufacturers.
The pressure rating of the valves and associated flanges must be at least equal to that of the pipes, or one grade higher than that of the pipes.
It is estimated that the issue lies in the procurement process; the valve manufacturer believes that CL300 valves can handle an operating pressure of 4.2 MPa, and indeed they are capable of meeting this requirement. CL300 corresponds to PN50. It is estimated that there is a significant price difference between CL300 and CL600; naturally, valve manufacturers choose CL300 in order to gain a competitive price advantage. The department in charge of the piping certainly doesn’t want to take responsibility. It is normal to refuse piping.
The pressure rating of the valve must be equal to or higher than that of the pipeline
Not only consistency is required; due to the operability of the valves, their design and usage requirements are even higher than those for pipes.
Pressure classes are classifications of the design pressure for piping systems established by professional organizations based on industrial practice, and are adopted in piping design standards across various countries. In the ASME/ANSI piping standards in the United States, the concept of CLASS is used, while international standards, including those in China, employ the concept of nominal pressure rating (PN). The various pipeline design standards specify the pressure-temperature ratings for different pipeline materials at various pressure levels, thereby providing a basis for the design of pipeline systems. The nominal pressure class (PN) value of a pipe is approximately equal to the pipe’s design pressure at cold conditions, expressed in BAR.
Valve pressure rating, pipeline design pressure rating
Generally, this is not allowed. If it is necessary to use it in an emergency, then it is necessary to check the allowable stress of the CL300 valve provided by the manufacturer at 200 degrees, to see if it is higher than 4.2 MPa. If it is, then it can be used, but that indicates that the design is conservative.
The pressure rating of the valve should be >= the pressure rating specified for the pipeline; generally, they are the same, or the valve’s pressure rating is chosen to be one level higher as a precaution
Theoretically, the CL300 model is capable of withstanding a working pressure of 4.2 MPa, but it is necessary to consult the design team to determine whether there could be sudden pressure changes in this location. In other words, it is important to see if a sufficient safety margin has been taken into account for a pressure of 4.2 MPa, or whether the opinions of the design institute should be followed