The RP1110 which is for liquid petroleum pipelines refers back to B31.4 and 49 Code of federal regulations part 195.
| "Bathula Raghuram \(Mumbai - PIPING\)" <R.Bathula@ticb.com> Sent by: materials-welding@googlegroups.com 24/10/2008 09:47
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Stress value at test temperature shall be considered while prolonged period with varying temperatures.
some time we do big systems like fire water network (or other buried piping) to be kept at design pressure for 24 hours, where pressure/temperature monitored with continuous P/T recorders.
B31.3 is has no such requirement, but in case of EN13480 it is held for 30min minimum at test pressure and bring back to design pressure for close visual inspection.
However Pipelines (designed to ASME B31.4/31.8 etc.) may require longer periods
for e.g. B31.4 indicates Hydro @ 1.25 time internal DP but not less than 4 hours
you may also note the caution given in B31.4
"When lines are tested at pressures that develop a hoop stress, based on nominal wall thickness, in excess of 90% of the specified minimum yield strength of the pipe, special care shall be used to prevent overstrain of the pipe."
Probably API RP 1110 may give you some guidance. I have not seen this.
Members please share your views.
-----Original Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com]On Behalf Of Aarpee
Sent: Friday, October 24, 2008 8:30 AM
To: Materials & Welding
Subject: [MW:1236] Hydro test-max holding period
As per B31.3 Hydro test is carried out at 1.5X Design Pressure.Holding
time for Piping spools is normally 30 minutes but at times 4-6 hours
for Gas applications.Can this be held for 24 hours?What is the
potential risk?It is normally indicated that after Hydro inspection
for 10-30 minutes at 1.5X Design Pressure,if you intend doing further
inspection then same can be done at a pressure not more than the
design pressure.Opinion of the group is being sought thro this mail
Regards
Aarpee
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