MAOP < Design Pressure ???

[CORPMEX]

Hi again,

I am using Ultrapipe to determine de remaining strength of a corroded pipeline. ASME B31.G compares the MAOP with the safe maximum pressure for the corroded area. But, Ultrapipe compares this last pressure with the Design Pressure.

Is the Design Pressure always greater than the MAOP? Is that why Ultrapipe uses the DP instead of the MAOP?.

CorpMex.

 

[gr2vessels]

corpmex,
The maximum operating pressure is / was always the minimum design pressure specified for a pressure equipment. The design pressure may be selected higher than the operating pressure, to include some contingency for unexpected additional lods. In no case, the design pressure should be less that the MAOP.
Do not confuse the operating pressure with the maximum allowable working pressure, which is usually higher than the design pressure, but not less than the design pressure.
Cheers,
gr2vessels

 

[SaCaZu]

I've read that Design Pressure can be used instead of MAOP in B31.G for the calculations...is it possible?

Thanks.

 

[gr2vessels]

Dear SaCaZu,
The rules of this forum requires you to start a new thread for your technical clarifications. Please do not derail the topic of this thread.
cheers,
gr2vessels

 

[jwshome]

Corpmex: You must be using an older version of UltraPIPE. The original B31G calculator in UltraPIPE (through version 9.99x) compared the MAOP of the corroded are to the Design Pressure from the corrosion monitoring module. This was found to be inconsistent with B31G. In versions 10x of UltraPIPE, the B31G module now contains a calculator to determine the MAOP of the uncorroded portion of the piping and compares the corroded MAOP to this value, providing consistent results with B31G.