[Discussion Post 66] What should be considered for shell and tube heat exchangers where the design pressure on the tube side is higher than the design pressure on the shell side?
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bg4.png [Discussion Post 66] What should be considered for shell and tube heat exchangers where the design pressure on the tube side is higher than the design pressure on the shell side? like: The test method and pressure of the pipe head should be stated on the drawing. How should it be written specifically?
For similar results, we often increase the experimental pressure on the shell side to be equal to the pressure on the tube side.
Technical requirements for chemical engineering drawings P54 In order to check the tightness of the connection between the pipe and the tube sheet (1) Increase the shell side test pressure to equal the pipe side test pressure. When using this method, the stress of the shell during the pressure test must first be checked. It is required that the calculated primary film stress at any point on the shell shall not exceed the stress of all materials during the test. It is required that the calculated primary film stress at any point on the shell shall not exceed the 90% yield limit of the material used at the test temperature (or the yield limit of 0.2% residual deformation). At the same time, the nozzle and flange can meet the strength requirements under pressure test. (2) If the above method cannot be adopted after calculation, or is unreasonable from technical and economic considerations, after the shell side and pipe side are pressure tested according to their respective requirements, the shell side shall conduct an ammonia leak detection test in accordance with Appendix A of HGT 20584 "Ammonia Leak Detection Test Method for Pressure Vessels".
1. Increase the shell side hydraulic test pressure to the tube side pressure 2, and add ammonia leak detection on the shell side.
Where does the second point come from: handshake
Pressure Vessel Design Engineer Training Manual Article 25.14.2
Pressure Vessel Design Engineer Training Manual Article 25.14.2
First check the stress of the shell during the pressure test. It is required that the calculated primary film stress at any point on the shell shall not exceed the stress of all materials during the test. It is required that the calculated primary film stress at any point on the shell shall not exceed the 90% yield limit of the material used at the test temperature (or the yield limit of 0.2% residual deformation). At the same time, the nozzle and flange can meet the strength requirements under pressure test.
Why should the shell side hydrostatic test pressure be increased to the tube side pressure?