Re: [MW:29523] Query related to Pressure testing of Existing piping/equipment - Looking for a right recommendation based on International Standard/ Guidelines

Check ASME B31.1-137.4.5 and 137.5.5 as an example. The holding time is a minimum of 10 minutes.

On Sat, Apr 27, 2019 at 6:22 AM ViNo Varughese <vinopvarghese@gmail.com> wrote:

Dear All,

I have read recently an Oil & Gas Journal regarding the hydro test Vs holding time and looking for more insight from Experts from different industries. There are few questions which I would like to get more clarity on -
1. What should be the recommendation for pressure testing of existing piping line which is repaired due to leak? Whether we should follow the Construction code or should we limit just above the MAOP? Is there any criticality rating based on which we need to consider the pressure test value, eg: H2S service.

2. Many times our Operation colleague request to consider the closure weld principal where we can do additional NDT on the welded joints instead of pressure testing. I do understand that NDT cannot be replaced with pressure testing. However, there are good chance of having a defect opened up which is on the verge of failure when the line is tested at 1.5/1.3 times the design pressure. How to deal with such situations when Asset Plant has been in Operation since 25+ years?

3. There is reference in the same Oil & Gas Journal - " A study of the causes of failures of Defects that Have Survived a Prior Hydrostatic Test". Appreciate if someone holds a copy of this article and please share in forum.

4. I think there is no International code referring to holding time of pressure testing. Just would like to get a reconfirmation on this.

Hope to see view from Experts all around different industries. I am sure it's a very routine repair in almost all of the Plants/Company and will add value to each one of us.

Best Regards
Vino

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