Number of hydrotest a component can withstand (ASME)
Number of hydrotest a component can withstand (ASME)
(OP)
I have a pipe, which after manufacturing, got hydrotested at 1.5 times design pressure as per ASME
Then it was erected, with the total piping and got hydrotested at site at 1.5 times again.
Now due to some modification, this pipe was modified. Again it is shop and site hydrotested?
My question is what happens to the metallurgy and stres,when u do multiple hydrotest.
Is there any limit on maximum times, a component can be hydrotested?
is it safe to do repeated hydrotests?
Then it was erected, with the total piping and got hydrotested at site at 1.5 times again.
Now due to some modification, this pipe was modified. Again it is shop and site hydrotested?
My question is what happens to the metallurgy and stres,when u do multiple hydrotest.
Is there any limit on maximum times, a component can be hydrotested?
is it safe to do repeated hydrotests?





RE: Number of hydrotest a component can withstand (ASME)
Cheers,
gr2vessels
RE: Number of hydrotest a component can withstand (ASME)
how can you say that "hydrotest" is an extension to the normal service conditions of pipe.
How we will get near yield limit, when we do repeated hydrotest.
Could you pls elaborate the theory?
RE: Number of hydrotest a component can withstand (ASME)
RE: Number of hydrotest a component can withstand (ASME)
A properly designed hydrotest puts no component into through-thickness yielding - however these is a small amount of yielding that will occur at local features. This yielding is beneficial as it can lead to a residual compressive stress on the inside surface. Any subsequent hydrotest would need to exceed the original hydrotest pressure to generate further yielding. If no yielding occurs in subsequent hydrotests, then the metal behaves linear-elastically throughout, and there is no cumulative damage.
There is a low-cycle fatigue limit, but you would have to hydrotest almost 1000 times before it might become an issue. You're not planning on doing that, right?
RE: Number of hydrotest a component can withstand (ASME)
i am not much familiar into material loading..
wer can i read about the effect of hydrotest..? any reference or code cases?
moltenmetal, could you please explain the selection of safe allowable stress and hydrotest ratio, if possible through an example
TGS4, pls explain more about the low cycle fatigue situation.. and you are right, i am not going for 1000.. LOL.. That was superb :)
RE: Number of hydrotest a component can withstand (ASME)
Cheers,
gr2vessels
RE: Number of hydrotest a component can withstand (ASME)
RE: Number of hydrotest a component can withstand (ASME)
RE: Number of hydrotest a component can withstand (ASME)
coolnicks37- Sometimes you just need a mentor or pay for a consultant. Eng-Tips is a great forum, but it is not a substitute for an engineering education, mentoring, and experience. This seems to be one of those times.
RE: Number of hydrotest a component can withstand (ASME)
Thank you for your time and answers.. Really appreciate all people and their answers..
Some more info which i got from internet is attached..
http://pipelineandgasjournal.com/pipeline-hydro-te...
RE: Number of hydrotest a component can withstand (ASME)
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Number of hydrotest a component can withstand (ASME)
As LittleInch stated, pressure testing of cross country pipelines is quite different than that imposed by ASME B31.1 or B31.3. An 80% design criteria per B31.8 requires a pressure to impose a load in hoop at 100% of the SMYS, minimum; at 72% design, 90% of the SMYS. Portions of the line will experience stress greater tha 100% of the SMYS based on elevation differences. Be specific, is the pipe in question designed and constructed to B31.3, B31.1, B31.4, B31.8 or other?
RE: Number of hydrotest a component can withstand (ASME)