Minimum design pressure of pipe

[Darshc]

Hi all,

In power plant engineering, normally we have used minimum design pressure of the pipe to be 50 psig. I want to know from where this basis of 50 psig is derived. In one of our project we have specified pipe design pressure to be 50 psig even if the operating pressure of the system is at atmospheric pressure. Is this value a mandatory to consider while calculating the design pressure?

DC

 

[ConstantEffort]

50psig is not mandatory in ASME B31.1. Paragraph 101.2 should help you out a little.

Code is a minimum though and your company can impose stricter requirements or higher minimums.

In one case a company put a similar minimum positive design pressure even on open ended lines AND required a hydro at 1.5x design pressure. The engineers were adamant that the line must be hydrotested, but they weren't too helpful with the how... that's construction means and methods, you see, and they're just design engineers.

 

[MJCronin]

Usually, this minimum design pressure is handled by the piping schedule established in the PIPE LINE CLASS for the project.

Most of the time, even low pressure piping systems are designated as Schedule 40 (for carbon steels) and schedule 10S ( Stainless and alloys).

By establishing a line class for every pipe in the plant, this problem goes away...

MJCronin
Sr. Process Engineer
Venture Engineering & Construction

http://www.VentureEngr.com