B31.3 hydro testing location clarification

[k3_at_ke]

Considering B31.3 345.1 required leak test. Before initial operation a leak test is to be performed to insure tightness. Seemingly this leads me to believe a hydro should be performed in place as final install. However 345.2.3 tells me subassemblies can be tested separately or as assembled.

I am trying to determine if a hydro is technically supposed to be performed in place as installed with the exception of slip blinding or if a system can be temporarily bolted and hydro performed in a laydown yard leaving the final install tie in bolt up to be trusted.

 

[MintJulep]

How do you want to manage the risk of a subassembly leaking vs. the connections to the subassembly once everything is in place?

 

[r6155]

See:
F345 TESTING
F345.2.3 Special Provisions for Testing. When piping
subassemblies are testedseparately, consideration should
be given to performing an additional leak test of the
assembled piping system prior to initial operation. The
test fluid should be nonhazardous to the process and
the people performing the examination. Examination
for leaks should be at all joints that have not been
previously examined for leaks, or that have been reas￾
sembled after being examined for leaks. Examples
include flanges where isolation blanks were removed
after the leak test and joints where instrumentation or
other components were removed for the leak test.

Regards

 

[k3_at_ke]

r6155 I don't see a (f345). You statements below are they opinion or is there code that mentions the reassembly of flanges. Thanks

 

[r6155]

See ASME B31.3 2020
APPENDIX F
GUIDANCE AND PRECAUTIONARY CONSIDERATIONS

Regards

 

[k3_at_ke]

r6155 I appreciate your help. I was looking in a 2012 copy. However this still leaves me in a position of discretion rather than absolution. Considering the code does permit the reassembly after testing but only cautions you to consider additional leak tests.

 

[0707]

Leak test is a final test prior to put the system in service, a leak test is normaly done with low air pressure soaping the weld seams. A hydrotest is a test done in a closed system, trough blind flages, to see if the system being tested under pressure, is able to structurely widstand the test pressure at what it is submitted.

regards

luis

 

[GBTorpenhow]

The code is silent as to where the required leak test takes place. It is certainly permissible to leak test flanged subassemblies in a shop, yard, or on the ground in the field before installation and leave the final flanged assembly connections untested. Also OK to test a complete piping system in situ, at some risk of discovering a leak and having to disassemble, repair, and reassemble installed piping.

Sound engineering judgement and/or owner specifications should determine whether leaving mechanical connections completely untested before commissioning/initial operation is advisable or not based on pressures, nature of the fluid, accuracy of specified flange torquing method, etc.

 

[0707]

Leak test is a final test prior to put the system in service, a leak test is normaly done with low air pressure soaping the weld seams.

 

[r6155]

The allowable rate of leak must be specified by the owner/user. See ASME V.

Regards