How is the hydrostatic test pressure for the 9.8MPa main steam pipeline determined?
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The main steam pipeline system S1 in our plant (￠450X38, 9.8 MPa, 545°C) has just been installed and is now ready for pressure testing. According to the requirements provided by the design institute, the pressure to be applied during testing should be 38 MPa; based on chemical engineering standards, this value is also around 37 MPa. However, according to electrical engineering standards, only 15 MPa is required. After consulting with other plants of similar type, it was found that few of them apply a pressure of 38 MPa (as such high pressures are dangerous, and it can be difficult to use pressure pumps to achieve that level of pressure). Some plants even do not carry out any pressure testing at all. I would like to ask those with experience: what should be the appropriate pressure for testing? ?
Please comply with the GB 50235-97-CHN standards for the construction and acceptance of industrial metal pipeline projects. The specific provisions are as follows: 7.5.3.7 When the designed temperature of the pipeline is higher than the testing temperature, the testing pressure shall be calculated using the following formula: Ps = 1.5P1/2 (7.5.3), where Ps represents the testing pressure (gauge pressure) in Mpa； P — Design pressure (gauge pressure) (MPa) ； 1 — Allowable stress of the pipe material at the test temperature (MPa) ； 2 — Allowable stress of the pipe material at the design temperature (MPa). When 1/2 is greater than 6.5, use 6.5. When Ps generates a stress exceeding the yield strength at the test temperature, the test pressure Ps should be reduced to the maximum pressure at which it does not exceed the yield strength.
According to GB50235-97 \"Code for Construction and Acceptance of Industrial Metal Piping Projects\", the strength test is conducted at 1.5 times the working pressure; therefore, the hydrostatic test pressure for main steam pipes at 9.8 MPa should be 14.7 MPa. The testing medium is clean water.
4# zfy_80522 agrees with the view in the second floor post; it is a test pressure that has been adjusted for temperature, rather than simply being a multiple of the test temperature. According to GB50235-97 \"Code for Construction and Acceptance of Industrial Metal Piping Projects\": 7.5.3.7 When the design temperature of the pipeline is higher than the test temperature, the test pressure shall be calculated using the following formula: Ps = 1.5P1/2 (7.5.3) Where Ps represents the test pressure (gauge pressure) in Mpa ； P — Design pressure (gauge pressure) (MPa) ； 1 — Allowable stress of the pipe material at the test temperature (MPa) ； 2 — Allowable stress of the pipe material at the design temperature (MPa). When 1/2 is greater than 6.5, use 6.5. When Ps generates a stress exceeding the yield strength at the test temperature, the test pressure Ps should be reduced to the maximum pressure at which it does not exceed the yield strength.
If not specified in the design documents, the pressure for water testing is 1.5 times the design pressure, while the pressure for gas testing is 1.15 times the design pressure!
The water pressure test pressure is 1.5 times the design pressure
According to GB50235-2010 \"Code for Construction and Acceptance of Industrial Metal Piping Projects\" and GB/T20801-2006 \"Code for Pressure Piping – Industrial Piping\", when the design temperature of the pipeline is higher than the test temperature, the test pressure shall be calculated using the following formula: Ps = 1.5P1/2. Here, Ps represents the test pressure (gauge pressure) in Mpa； P — Design pressure (gauge pressure) (MPa) ； 1 — Allowable stress of the pipe material at the test temperature (MPa) ； 2 — Allowable stress of the pipe material at the design temperature (MPa). 7 U3 X) When 1/2 is greater than 6.5, use 6.5. When Ps generates a stress exceeding the yield strength at the test temperature, the test pressure Ps should be reduced to the maximum pressure at which it does not exceed the yield strength.