Minimum Pressurization Temperature (MPT) 1

[jtseng123]

Dear all,

Can someone use simple term to explain "Minimum Pressurization Temperature (MPT)", the purpose and why it is needed ?

Thanks.

 

[metengr]

This is typically used where you want to pressure test a component but because of poor notch toughness properties or concern over brittle fracture, you use a reduced pressure to ensure you do not subject the component to brittle fracture under tensile hoop stress from pressure.

 

[jte]

In many cases MPT is equivalent to MDMT; where in-service embrittlement can occur the two terms can be different. Given a lack of definitive (i.e. code) definitions of MPT, the definitions can vary from practitioner to practitioner. Some point out that the MDMT in new construction (say Section VIII) should encompass the potential for in-service embrittlement but the reality is that this very rarely happens.

MPT would be of interest not only for post construction (i.e. field) hydrotesting, but also is frequently a limitation in startups when equipment may not be warm enough to handle the pressure the ops folks would like to see. It can be difficult to heat inches of steel with hydrogen at relatively low pressures.

jt