Piping strain equalization time - quantitative references?
Piping strain equalization time - quantitative references?
(OP)
I'm reviewing some pneumatic test procedures (and doing the blast radius calculations, etc...) but I'm having trouble finding any good reference materials on how long to hold at the various pressure steps to allow the piping strain to equalize. B31.3 just says to hold it "long enough" and B31.1 just says to raise the pressure gradually; which kind of seem like non-committal blanket-statements to me and I'd rather not pass those on to those following the procedures.
The only quantitative statement I have found is in ASME PCC-2-2011 (Repair of Pressure Equipment and Piping) which says to "hold for a minimum of 3 min to allow strains to equalize." Since we are testing short lengths of bent instrument tubing and fittings (3/8", or less, at 2200 psig, or less), 3 minutes seems excessive to me but I would like to find some references, perhaps correlating to pipe size, length, pressure, etc... before I suggest a shorter time period.
So, short of me going for a Materials Degree, does anyone know of any references on the subject?
Thanks.
The only quantitative statement I have found is in ASME PCC-2-2011 (Repair of Pressure Equipment and Piping) which says to "hold for a minimum of 3 min to allow strains to equalize." Since we are testing short lengths of bent instrument tubing and fittings (3/8", or less, at 2200 psig, or less), 3 minutes seems excessive to me but I would like to find some references, perhaps correlating to pipe size, length, pressure, etc... before I suggest a shorter time period.
So, short of me going for a Materials Degree, does anyone know of any references on the subject?
Thanks.




