What to do if the pipeline pressure testing pressure exceeds the allowable pressure for flanges
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The operating pressure of the steam pipeline is 1.25 MPa, and the temperature is 193°C； Design pressure: 1.4 MPa, temperature: 200 ； The pipeline pressure rating is set at 1.6 MPa. In accordance with standard GB50184, and after taking into account the temperature correction factor, the hydraulic pressure comes out to be 2.5 MPa. However, according to HGT20592, the pressure used for flange testing should not exceed 1.5 times the maximum allowable pressure at normal temperature, that is, it should not be more than 2.4 MPa – which is lower than the value calculated for pipeline testing How should this situation be handled? I seek advice from experts
I don’t quite understand; is it possible to conduct the test in another way?
Should the flanges and gaskets be upgraded by one level?
There are only two types: hydraulic and pneumatic. Design institutes usually do not opt for the pneumatic option, as it is dangerous
It seems there’s a problem with yours; the design pressure is 1.4 MPa and the temperature is 200； The pipeline pressure rating is set at 1.6 MPa; in accordance with standard GB50184, and after taking into account the temperature correction factor, the hydraulic pressure comes out to be 2.5 MPa. This value should be based on the design pressure, rather than the pipeline pressure rating
It can only be high, not low. What if there’s a problem with the padding? Even if nothing happens for now, who can guarantee that nothing will go wrong in the future? It’s better to be cautious to avoid problems
This must be a design flaw – for some components, the pipes need to be designed with a pressure rating that is one level higher than specified in the design. If the design calculation calls for 1.6 MPa, then materials with a pressure rating of 2.5 MPa should be used
The design pressure is 1.4 MPa, with the pipe grade set at 1.6 MPa
The design pressure for the pipeline is 1.4 MPa; generally, materials with a pressure rating of 1.6 MPa would be sufficient. However, due to the high temperature or high level of risk involved, it is necessary to increase the pressure rating further, and materials with a pressure rating of 2.5 MPa are required. Otherwise, situations like yours will occur.
It was indeed calculated using the design pressure, but I used the wrong allowable stress value; it should be 1.4*1.5*130/123=2.22MPa