Relationship between pipeline pressure class and design pressure
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This post was last edited by tuohai00 on 2018-6-23 16:05. I would like to ask: what is the relationship between the nominal pressure class of a pipe and its design pressure? Are they rounded to the nearest value? Or some other relationship? Please specify in detail (preferably citing the source), thank you very much. For example: medium is nitrogen, design temperature is 50 degrees, design pressure is 0.6 MPa. Is it acceptable to use grade M for the pipeline?
Could anyone with experience give some advice? Urgently waiting
The nominal pressure rating must be higher than the design pressure of the pipeline. The nominal pressure classes are specified; for example, according to European standards, they include 0.6 MPa, 1.0 MPa, 1.6 MPa, 2.5 MPa, 4.0 MPa… The design pressure is determined based on the operating conditions. For example: the medium is nitrogen, the design temperature is 50 degrees, the design pressure is 0.6 MPa; the nominal pressure is then either 1.0 MPa or 1.6 MPa. The numbering of pipeline grades varies from one design institute to another, but the corresponding nominal pressures are all specified values.
Thank you for the reply. I’ve confirmed with the design institute, and there is no direct relationship between the two. The nominal pressure is merely the pressure resistance rating of the pipeline material at normal temperature under the corresponding operating conditions; as long as it is higher than the design pressure, it’s sufficient.
"The nominal pressure is merely the normal-temperature pressure resistance rating of the pipeline material under the corresponding operating conditions; as long as it is greater than the design pressure, it is sufficient. "There is an error in this statement. It’s true that the nominal pressure must be greater than the design pressure, but it’s not enough for it to be simply greater; the relationship between temperature and pressure needs to be taken into account. Calculations or reference tables are required, and in cases of high temperatures, even a slightly higher pressure level may not be sufficient.
What was said upstairs is correct. Pipe factories manufacture a range of pipes with different materials, sizes, and wall thicknesses in accordance with standards, while the process design involves calculating the design pressure and design temperature based on the operating conditions. With the design pressure and design temperature, along with requirements such as the corrosion allowance, the material control department of the design institute (I think that’s how it’s called) prepares a unified list of pipeline materials to determine what nominal pressure pipes should be used for each pipeline.