Regarding hydrotest pressure and temperature relationship
Regarding hydrotest pressure and temperature relationship
(OP)
Dear sir/all,
We have 2.5 KM of C.S. pipe line, and we have start the hydro test at 5pm with 18kg/cm2 and as per holding time of two hours , it is completed at 7pm , without any leakage or seepage.
But after completion of 2 hrs., pressure decrease by 1hrs. and it found 17kg/cm2.
We stated that due to decrease in temperatures, pressure also decrease. but client not ready to accept.
Pls help.
Design pressure is 12kg/cm2 and hydro test pressure is 18 kg/cm2.
(Sorry to members, wrongly posted in BPV forum, so posted in this, piping).
Regards
Prasad
We have 2.5 KM of C.S. pipe line, and we have start the hydro test at 5pm with 18kg/cm2 and as per holding time of two hours , it is completed at 7pm , without any leakage or seepage.
But after completion of 2 hrs., pressure decrease by 1hrs. and it found 17kg/cm2.
We stated that due to decrease in temperatures, pressure also decrease. but client not ready to accept.
Pls help.
Design pressure is 12kg/cm2 and hydro test pressure is 18 kg/cm2.
(Sorry to members, wrongly posted in BPV forum, so posted in this, piping).
Regards
Prasad





RE: Regarding hydrotest pressure and temperature relationship
See my previous response.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
Was the pipe buried?
What was the temperature at the beginning and at the end of the test?
RE: Regarding hydrotest pressure and temperature relationship
dP/dT|v = dA/dV|T= -d2F/dT/dV, and you would likely need to use a steam table based on a canonical equation of state such as the NBS/NRC steam tables for these partial derivatives.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
Thanks for response.
First of all, Dia of pipe is 8".
Pipe is painted with MIO and joint painting only balance.
There is no air in the line.
Temperature is app. 36 degree in starting and 34 degree at end time.
Length of line will affect it or not.
Is there any standard chart between temperature and pressure, or any thumb rule for such cal.
Regards
Prasad
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
If this is above ground ( sounds like it) then you should be able to inspect the entire line, even in 2 hours and show no leakage?
If this is an above ground line, it would take longer than 2 hours for such a small ambient air temperature drop to affect the entire volume of water, even assuming the water was at 36 degrees to start with ( that's rather warm)
So what is it? an A/G line on supports where you can visually check EVERY joint / length of pipe or a buried line where you haven't actually got proper temperature measurments of the pipe/water temperature and didn't give it enough time to stabilize before the test?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Regarding hydrotest pressure and temperature relationship
Thanks for reply.
Regards
Prasad
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
I'd expect if it was now out of the sun during the test period, the water will have fallen more than the 2deg C ambient change.
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship
RE: Regarding hydrotest pressure and temperature relationship