NDT to piping that have been working over the MAWP determinated by ASME B31.3 3

• Jan 21, 2023

• #2

1503-44

Petroleum

Jul 15, 2019

6,705

ES

Assuming Cyclic stresses or thermal damage did not occur to the material and if pressure stress did not exceed the elastic limit, deformation is not permanent and geometry returns to previous form (perhaps minus some hysteresis effect). If you can shows some inelastic deformation remained, then recalculation of a new MAWP based on permanent remaining wall thickness may be in order.

Some practices might even treat this as simply a "pressure test during operation", possibly even providing a reason for uprating the MAWP. The pipeline rating procedure for pipelines not recently, or even never hydrorested, often have a provision for pressure rating by determining MAOP/MAWP based on the highest operating pressure experienced during the last year of operation.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

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• Jan 21, 2023

3
• #3

The Obturator

Mechanical

Feb 22, 2010

667

GB

You stated "....the PSV failed to open..." are you not more concerned about this? a device which is the last line of defence against life and property?


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

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• Jan 21, 2023

• #4

r6155

Mechanical

Jan 12, 2010

3,011

AR

1) @ The Obturator
My star for you.

2) See Acoustic Emission Examination in ASME V to check integrity.

Regards

 

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• Jan 21, 2023

• #5

XL83NL

Mechanical

Mar 3, 2011

3,120

NL

136% of MAWP? Or 36% over design pressure (or perhaps set pressure of the PSV)? They’re completely different things. MAWP is uncommon in piping but more for vessels. A pipe usually has a much larger over the design pressure before it reaches its ‘MAWP’. That margin may be of importance here.

Huub
- You never get what you expect, you only get what you inspect.

 

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• Jan 21, 2023

• #6

1503-44

Petroleum

Jul 15, 2019

6,705

ES

I would imagine the high pressure problem has been solved and he is just contending with possible after effects, but we actually don't know if it was a PSV malfunction, incorrect setting, or what is often the usual case, a closed block valve in front of the PSV.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

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• Jan 22, 2023

• #7

Krausen

Mechanical

Jan 1, 2013

295

US

MAWP is technically a ASME Section VIII term used for pressure vessels only. In this case, you overpressured B31.3 piping beyond it's design pressure at pretty much ambient temperature. The piping should have been hydrotested to at least 1.5x the design pressure at ambient temperature before it was ever put into service, so it's no surprise the piping held up to this. Based on your data, the pipe remained under it's minimum required yield strength (in hoop stress) during this excursion. Did your system have any flanges or other limiting components in it that were also overpressured with the A106B pipe? Typically your "weak link" in most pressure piping systems are your bolted flanges, which can be visually or LDAR checked for leaks when overpressured.

 

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• Jan 22, 2023

• #8

r6155

Mechanical

Jan 12, 2010

3,011

AR

@ fernandomaggi
Your numbers are wrong. You must calculate the stress with the actual thickness of the pipe.

Regards

 

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• Jan 23, 2023

• #9

LittleInch

Petroleum

Mar 27, 2013

23,006

GB

Try looking at Appendix V of ASME B 31.3. Whilst tha tis about temperature you might be able to use it for pressure.

But at this sort of overpressure (i.e. less than the hydrotest), you simply need to do an engineering assessment and physical check of the system.

It almost certainly hasn't yielded anywhere so no real NDT to do.

But you need to find out how it happened, why it happened and what is being proposed to ensure that as far as possible it doesn't happen again. Like why did the control and safety systems allow this to happen? Procedures and operator awareness are not reliable enough to be used as the means to protect piping systems.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

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