Why is the test pressure for this pipeline greater than 1.5 times
Thread Content
RG-12001310“A1D Propane gas XV-20808P-120061A(23.7/260)/160.77/1.13415/(-23/65)1/1.45F Composite aluminum magnesium silicate tube shell, 110 aluminum alloy thin plate √2.70 GC2/SHB120-108/113. The design temperature for this pipe is 415/(-23/65), the design pressure is 1/1.45, and the test pressure is 2.70; 2.70 is 1.86 times greater than 1.45. Why is it more than 1.5 times? If we choose to conduct a pressure test, what pressure should be used?
When the design temperature of the pipe is higher than the test temperature, the test pressure is calculated as follows: Test pressure = 1.5 × Design pressure × (Allowable stress of the pipe at the test temperature / Allowable stress of the pipe at the design temperature). The temperature correction factor obtained by comparing the allowable stresses of pipes at 415 degrees and 20 degrees is definitely greater than 1; therefore, the test pressure will definitely be more than 1.5 times the design pressure
Because the strength reduction of the material at 415°C needs to be taken into account
The pressure test value is calculated as the cold working pressure (CWP) of the corresponding material at its nominal pressure rating multiplied by 1.5; this value depends on the material and the nominal pressure. For low-pressure gas seals, the test pressure is 0.6 MPa. For more details, refer to standards such as GB/T 26480 or API 598
When the design temperature of the pipe is higher than the test temperature, the test pressure shall be calculated using the following formula: 1. PT = 1.5 × PT / t, where PT is the test pressure (gauge pressure) in MPa, P is the design pressure (gauge pressure) in MPa, T is the allowable stress of the pipe material at the test temperature in MPa, and t is the allowable stress of the pipe material at the design temperature in MPa. 2. When T / t is greater than 6.5, 6.5 shall be used. 3. The stress of the pipeline under test pressure conditions should be checked. When PT generates a stress exceeding the yield strength at the test temperature, the test pressure PT should be reduced to the maximum pressure at which it does not exceed the yield strength