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
CONFIDENTIALITY NOTICE
This e-mail and any attachments there to contain information, which is confidential, proprietary, privileged and/or protected from disclosure by intellectual property rights and are intended for the sole use of the recipient(s) named above. If you are not the intended recipient of this message you are hereby notified that any dissemination or copying of this message is strictly prohibited. If you have received this e-mail in error, please notify the sender either by telephone or by e-mail and delete it from any computer. Although this e-mail and any attachments thereto are believed to be free from any virus or other defects, which might affect any computer or IT system, it is the responsibility of the recipient to ensure that they are virus free. We are not liable for any loss or damage arising in any way from receipt or use there of. Thank you.
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
-~----------~----~----~----~------~----~------~--~---
No comments:
Post a Comment