[MW:1264] Re: 1236] Hydro test-max holding period

Dear mates,

I do agree with what is said below. But, im not expert in pipeline testing. Im dealing with Static Equipments designed as per ASME SEC. VIII Div.1.

As per the code, clause UG-99, where it says for any Fabricated equipment the minimun Hy. test pr. shall be 1.3 times Design Pr. multiplied by the stress ratio and No limit on upper limit. The Upper limit depends on the criticality of Vessel.

But there is no confirmation on Holding time of the Hy. Pr. Normally in our shop it is done for 1 hour or till all the joints are visually inspected. it relies on the Inspector. it may extend to 2-3 hours.

But, in line with that in Our EIL Spec. 6-15-0001 Rev.3 Cl.7.2.1, it had been said the Hy. test pressure shall be for an hour.

 

These are for Static Equipments. If someone can say it for Rotating Equipment i will be usefull.

 

Regards,
Prabhakar.H
Chennai.

On Fri, Oct 24, 2008 at 1:17 PM, Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com> wrote:

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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