knapee
Petroleum
- Mar 9, 2011
- 100
Dear Sir/Madam :
I have difficult in understanding test pressure in tightness test. Tightness test is applied to the piping system which handling harzdous, chemical, and hydrocarbon process fluid. (Note. vent, drain or piping open to atm, pressure vessel,heat exchanger, pump, turbines, compressor, blower is not included)
In my case, air test pressure is used 5kg/cm2g when the normal operating pressure is 5 kg/cm2g or more. First, connecting air supply to point, and pressurizing the system up to 5 kg/cm2g, then disconnectting the air hose, then checking all joints (such as threaded, socked-welded, butt-welded and flanged) for any leaks by spraying soap suds.
And, it confuse me that the difination of test pressure written in ITB pneumatic test.
1. Preliminary air test not more than "1.7 barg" may be made to locate marjor leak befroe a hydrostatic test.
2. Pressure to "0.5 barg" and hold for a sufficient length of time to allow piping to equalise strains.
3. pressurise gradually in 10% steps to 60% of the specified test pressure and holdfor a sufficient lenghth of time to allow piping to equalise strain.
4. Reduce pressure to 50% of the specified test pressure and visuall inspect all joint leaks.
5. The test pressure shall be helld for 2 hours and then reduced to design pressure after wich all joints shall be inspected for leak with soap sud.
6. The pneumatic "test pressure" sahll not exceed "110% of design pressure".
As the operating pressure in pipe is greater than 5 kg/cm2g, I am not quite sure 5 kg/cm2g as test pressure is right or not .
If there is a pipe whtich operating pressure is 10 kg/cm2g, which is correct test pressure to be used for air tightness test?
Should I used 5kg/cm2g or 110% of 10kg/cm2g as air test pressure or hydraulic tightness test instead of air tightness test in this case?
And, why is that the liquid testing medium always be instroduced at the system low point?
How can this to avoid air pocket formation ?
Your generous help is always appreciated
I have difficult in understanding test pressure in tightness test. Tightness test is applied to the piping system which handling harzdous, chemical, and hydrocarbon process fluid. (Note. vent, drain or piping open to atm, pressure vessel,heat exchanger, pump, turbines, compressor, blower is not included)
In my case, air test pressure is used 5kg/cm2g when the normal operating pressure is 5 kg/cm2g or more. First, connecting air supply to point, and pressurizing the system up to 5 kg/cm2g, then disconnectting the air hose, then checking all joints (such as threaded, socked-welded, butt-welded and flanged) for any leaks by spraying soap suds.
And, it confuse me that the difination of test pressure written in ITB pneumatic test.
1. Preliminary air test not more than "1.7 barg" may be made to locate marjor leak befroe a hydrostatic test.
2. Pressure to "0.5 barg" and hold for a sufficient length of time to allow piping to equalise strains.
3. pressurise gradually in 10% steps to 60% of the specified test pressure and holdfor a sufficient lenghth of time to allow piping to equalise strain.
4. Reduce pressure to 50% of the specified test pressure and visuall inspect all joint leaks.
5. The test pressure shall be helld for 2 hours and then reduced to design pressure after wich all joints shall be inspected for leak with soap sud.
6. The pneumatic "test pressure" sahll not exceed "110% of design pressure".
As the operating pressure in pipe is greater than 5 kg/cm2g, I am not quite sure 5 kg/cm2g as test pressure is right or not .
If there is a pipe whtich operating pressure is 10 kg/cm2g, which is correct test pressure to be used for air tightness test?
Should I used 5kg/cm2g or 110% of 10kg/cm2g as air test pressure or hydraulic tightness test instead of air tightness test in this case?
And, why is that the liquid testing medium always be instroduced at the system low point?
How can this to avoid air pocket formation ?
Your generous help is always appreciated
