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According to the definition of pressure pipelines in GB/T 20801-2020, {the maximum operating pressure is greater than or equal to 0.1 Mpa}. What is the relationship between this maximum operating pressure and the design pressure? When determining whether a pipeline qualifies as a pressure pipeline, should the design pressure or the operating pressure be used as the basis for assessment?
Definition of pressure pipelines: Pressure pipelines refer to tubular devices that use a certain pressure to transport gases or liquids. They are defined as pipelines with a maximum operating pressure of 0.1 MPa (gauge pressure) or more, carrying gases, liquefied gases, steam, or liquids that are flammable, explosive, toxic, corrosive, and have a maximum operating temperature equal to or higher than their standard boiling point; such pipelines also have a nominal diameter of 50 mm or more. Except for pipes with a nominal diameter of less than 150 mm and a maximum operating pressure of less than 1.6 MPa (gauge pressure), as well as the pipes that form part of the equipment used for transporting non-toxic, non-flammable, and non-corrosive gases.
Yeah, this is the exact wording from the standards. I just want to know what the relationship is between the maximum operating pressure of a pipeline and its design pressure
The design pressure is usually higher than the maximum operating pressure of the pipeline, with the maximum operating pressure serving as the basis for measurement. It has nothing to do with the design pressure.
Okay, thank you. I saw someone on the forum say that design pressure should be used for calculations, and I was confused, so I created a post to ask
The pipeline design class should be the design pressure, right?
I just want to know what the relationship is between the maximum operating pressure mentioned in the standards and the design pressure. I’ve seen many people on forums say that in practice they define pressure pipelines based on the design pressure, which confuses me. I think what the standards refer to is the maximum operating pressure – it should be that value, not the design pressure. If it were supposed to be the design pressure, then why didn’t the experts define it as such when drafting the standards?
In my personal view, the design pressure is higher than the maximum operating pressure; however, the classification of pressure pipelines is still based on the maximum operating pressure. During design, it may be necessary to use a higher classification level depending on the actual conditions, but the classification for inspection purposes remains based on the maximum operating pressure.