Newbie seeking advice on the design pressure for oxygen pipelines
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The nominal pressure of the oxygen pipeline is 4.0 MPa. How to calculate the design pressure and operating pressure? I would be greatly grateful if experts could provide guidance, preferably with references to standard sources. Thank you! ! ! !
What does your 4.0 refer to – operational stress?
It seems like the original poster has mixed up the order – there needs to be work pressure first
The design pressure is generally 1.5 times the operating pressure
Generally, it is necessary to know the operating pressure, or rather the maximum operating pressure, in order to determine the design pressure. Then, based on the design pressure, design temperature, and pipe material, the nominal pressure is determined. It seems that now the process has to be reversed; in other words, it is only possible to determine the maximum allowable operating pressure based on the pipe material and temperature, while the actual operating pressure remains unknown. The latter approach is very uncommon.
Oh, the drawing specifications specify the nominal pressure. I read in the standards that the nominal pressure should be ≥ the design pressure, which is equal to 1.15 times the operating pressure. I’m not sure if this is correct; could you please advise?
The nominal pressure being ≥ the design pressure is correct. The design pressure and operating pressure need not necessarily be 1.15 times each other. Typically, the design pressure is determined through a comprehensive consideration of various factors; for example, the properties of the medium are taken into account – in the case of liquid ammonia, its saturated vapor pressure is considered. Generally, the design pressure is at least 2.0 or 2.2 Mpa. Additionally, the pipes connected to the equipment must have a pressure rating that is no lower than that of the equipment they connect to. There are also considerations such as whether safety valves are installed on the pipes and what their set pressure is... etc. Using 1.1–1.2 times the operating pressure as a basis for determining the design pressure is merely a basic empirical value. There must be documents among the existing drawings that specify the medium properties, operating parameters, and design parameters; go and look for them – it’s not guesswork.