Hydrotesting without exposing an Underground Line

[Inspectengr]

Thanks for the reply.

In our case we are doing following for underground piping inside plantsite.

The line will be laid and coat wrapped. The joints area coat wrap will be done seperately. The joint area will be filled with sand. During testing the joint area will be exposed for visual inspection.

With this arrangement i think test with min. stay time can be done or do we need to expose complete line area?

[ashfaqanwer]

With this arrangement that the weld joints shall be exposed during the hydrostatic testing, yes the holding time can be decreased down to 04 hours as remaining piping is still covered.
Same is the case applicable for insulated pipelines with weld joints exposed.
Some people reduce this time further down to 1-2 hours. It's your choice how stringent you want to be with QC requirements.

[arcpro]

Hydrostatic testing is a check of mechanical integrity of the whole piping not only weld joints.
In your case, joints are exposed but still the piping has been coated / wrapped which may cause any seepage not to come to your notice. Even with small seepages, you would not be observing any pressure drop on gauges.
Final words, holding time must be at least 02 hours.

[mechcolor]

I know about a specific reference also about 4 hours with insulation but could not find at the moment.
Will see if I can find that.

[Inspectengr]

Thanks

[ashfaqanwer]

You are welcome Inspectengr.

[mechcolor]

Hello Inspectengr,
Look ASTM E-1003 - Standard Method for Hydrostatic Leak Test
In para 11.2.3 it has been stated that "if outside of the system has been covered by insulation which is not removed, increase the test time be a factor of 10, or maximum to 04 hours."
You can follow this reference for coated / wrapped line also.

[qaisarabbas]

Mechcolor,

Thank you for quoting the standard reference with forum members.
I was also searching any code / standard reference for the same requirement (max. time of hydrotesting when line is not exposed) a few months ago, but could not found that out at that time. Thank you for knowledge sharing.

[arcpro]

Hi mechcolor,
Thanks for providing a good reference.