Please also be aware that the pressure test has a secondary effect:
It is strengthening the piping against fatigue. The effect has been
described in the book, Charles Becht IV: "The complete Guide to ASME B
31.3" (available from ASME, and maybe availbale in your technical
library).
The pressure test gives an overstressing of the piping, resulting in
that any crack tips of micro-cracks in the piping components or welds
are being blunted during the overstressing. The blunting (rounding of
crack tips) results in improved resistance to fatigue.
It is worth to take the above into consideration if you are thinking
about avoiding pressure test of certain piping systems, for example by
replacing the pressure test by additional NDT. The additional NDT cannot
give the improved resistance to fatigue.
regards
Kristian Lund Jepsen
-----Original Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com] On Behalf Of Pisat, R.
(Rahul)
Sent: 18. juni 2010 10:54
To: materials-welding@googlegroups.com
Subject: [MW:5645] Hydrostatic pressure testing of piping systems - is
it for leak test or for strength test ?
Hello All,
I have one question regarding scope of Hydrostatic pressure testing of
piping systems.
As per ASME B31.3, Hydrostatic pressure testing of the piping systems is
defined as Hydrostatic leak test ie to check each piping system to
ensure tightness.
The PED (97/23/EC) guidelines & EN 13480 pressure piping code ask for
PROOF TESTING, ie by Hydrostatic testing, of the piping systems to check
the Strength & Integrity of the piping systems.
Why there is such difference between the approach/aspect of Hydrostatic
testing ?
If in 31.3, Hydrostatic pressure testing is only defined for check the
tightness ? how can one satisfy the PROOF TEST requirement of PED for
ASME B31.3
Your kind replies will be highly appreciated.
Kind regards
Rahul
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