hydrostatic test ASME SecI 1

[fazel1]

According to PG-99 (Hydrostatic test) in ASME SecI, at no time during the hydrostatic test shall any part of the boiler be subject to a general primary membrane stress greater than 90% of it’s yield strength at test temperature.
1- How can we check this stress in all parts of the boiler?
In first stage of the hydrotest the pressure shall increase gradually to 1 1/2 times the maximum allowable working pressure.
2-What does gradually mean? Is the rate of pressure increase important?
In PG-99.2 it is stated that the pressure may maintained at MAWP while the boiler is carefully examined .
3-Is there any maximum (time) for this maintenance?
4-How many pressure gages are needed for this test?
5-Is there any special rule for locating the pressure gages?

 

[metengr]

1- How can we check this stress in all parts of the boiler?

The statement....at no time during the hydrostatic test shall any part of the boiler be subject to a general primary membrane stress greater than 90% of it’s yield strength at test temperature... is a general guidance statement in PG-99.1 that requires the ASME certificate holder and Inspector to review all calculations before hydrostatic testing. The Code is a design by rule but also provides guidance for design by analysis, and this is what this statement references.

In first stage of the hydrotest the pressure shall increase gradually to 1 1/2 times the maximum allowable working pressure.
2-What does gradually mean? Is the rate of pressure increase important?

Gradually is determined by the Certificate holder in a hydrotest procedure, and this procedure is approved by the Inspector. In reality, gradual is determined based on your control of pressure using hydrostatic test equipment. In other words use a pressure rise ramp rate that you can control in the event a leak occurs during the application of hydrostatic test pressure.

In PG-99.2 it is stated that the pressure may maintained at MAWP while the boiler is carefully examined .
3-Is there any maximum (time) for this maintenance?
4-How many pressure gages are needed for this test?
5-Is there any special rule for locating the pressure gages?

Answers to questions 3,4,5 are going to be determined by your Inspector. They need to be involved with reviewing and approving your hydrostatic test procedure.