Discussion on pressure pipeline grades and flange issues for manual valves and pneumatic valves
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Once the pressure class of a pressure pipeline is determined, how is the pressure class of the connection flanges on the valves installed on that pipeline determined? Are there any regulatory requirements? For example, if a pipeline has a pressure rating of 16 kilograms, but the operating pressure of the fluid inside it is only 5 kilograms, can valves and connection flanges with a pressure rating of 10 kilograms be used?
The pressure rating of the valve fittings must be greater than or equal to the pressure rating of the pipeline. This issue was discussed before: https://bbs.hcbbs.com/thread-423017-1-1.html
The common pressure ratings for valve flanges in general use are PN10 (cast iron), PN16, 25, …… (cast steel). If a higher safety factor is required, as well as stricter physical and chemical conditions for the medium, it is best to choose the PN16 grade. Search for other relevant standards.
This task is handled by the material control department, which calculates and determines the pressure rating of the pipes based on the conditions and materials provided by the process engineering team; accordingly, the pressure ratings for the fittings and valves used on those pipes are also determined.
The selection of the pressure rating for pipeline accessories, including valves, is determined based on the nominal pressure rather than the pressure at which the medium is used. Not less than the pressure class of the pressure pipeline.
Are there any specific calculation formulas or coefficients?
The pressure rating of the connection flange for the valve on the pipeline should be the same as that of the pressure pipeline
This post was last edited by AtlantisH on 2018-8-8 at 10:50. The maximum allowable operating pressure of any pipe component must not be lower than the design pressure of that pipe. Flange and valve standards provide various tables from which it is possible to find out the maximum allowable operating pressure for different materials at corresponding temperatures.
Another key factor in determining the pipe material grade is the medium temperature! The determination of the pipe material grade is not based solely on pressure; temperature also plays a role. For example, if a pipe has a pressure rating of 16 kilograms, this only indicates that the pipe can withstand a pressure of 16 kilograms at normal temperatures. As the temperature of the fluid increases, the pressure that the flange components in the piping system can handle decreases accordingly. It is recommended that you consult the standards for flanges specified in SH3406 or HG20592 regarding temperature and pressure requirements for flanges. In summary, once the pressure rating of the pipe is determined to be 16 kilograms, the pressure rating of the flange components in the piping system must be equal to or greater than PN16. I hope this helps.