Impact on material after wrong pressure test 4

[awastha]

What are the adverse effects on material, if equipment is pressure tested at twice the rated pressure by mistake. Is it advisable to do any NDTs to see the condition of the material?

 

[monkeydog]

awastha,
I would start with a structural analysis, determine how close you got to yield limits of the material, and where you did, get close, evaluate what type of NDT is available to perform.

 

[metengr]

I would add you better check for permanent distortion of the pressure retaining item. See below as an example from ASME Section VIII, Div 1

This Division does not specify an
upper limit for hydrostatic test pressure. However, if the
hydrostatic test pressure is allowed to exceed, either intentionally
or accidentally, the value determined as prescribed
in (c) above to the degree that the vessel is
subjected to visible permanent distortion, the Inspector
shall reserve the right to reject the vessel.

 

[awastha]

Thanks for that update. So as i understand this lands up on the visual examination for any distortion. Don't we need more confirmation than the visual inspection? Or should we say for example if it passes Hydro test without the leak, It is fit to use in service.

 

[metengr]

It should be up to the Authorized Inspector to decide on final outcome. If it were me, I would perform a visual examination first, to check for distortion (general or localized). If localized distortion is found, nondestructive testing would possibly be next to ensure no cracks or tears.

In my experience, a higher than normal hydrostatic test, even 2X design pressure at ambient temperature, usually presents no problem to pressure retaining items because of the margins used by code of construction rules in determining minimum thickness under pressure.

 

[weldstan]

As monkeydog stated, check the applied stress vs the specified minimum yield strength of the material in hoop. Was the SMYS exceeded? If exceeded, then check vs actual yield strength on the CMTR. As metengr stated the SMYS will not be exceeded on pipe systems per B31.1 or B31.3.