Regarding heat exchanger pressure testing
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The normal construction of pressure testing for heat exchangers generally involves three steps: first the shell side, then the tube side, and finally pressure testing of the shell side. Personally, I think two units are sufficient – one test for the shell side and one for the tube side.
I think the methods for pressure testing heat exchangers with different structures are different.
To answer this question, one only needs to look at P94-95 in GB151.
Lou said that this pressure testing method can be applied to new products that have already passed pressure testing before leaving the manufacturer’s facility; if one of the tubes in the heat exchanger is leaking, it’s not possible to conduct pressure testing on the tube side
Foreign manufacturers have another approach for shell-and-tube air coolers of the cartridge type (we produce them according to their designs). Pressure testing is carried out during the final assembly: first, water is filled on the tube side, and the pressure is maintained at 1.25 times the design pressure for 30 minutes; then water is filled on the shell side, with the pressure again maintained at 1.25 times the design pressure for 30 minutes. After that, the water from the tube side is drained, and the pressure is held for another 30 minutes – only if all tests pass is it considered acceptable. Overall, only welds of type AB are required to be inspected using radiographic testing, while for the remaining welds, ultrasonic testing is applied to a few specific areas as required by ASME. So I think what you say makes some sense, but it’s not absolute; proper pressure testing should simulate actual operating conditions, with testing carried out in the order in which the medium flows
Should the pressure difference across the shell and tube sides be taken into consideration? Or should the tube side and shell side be tested up to 1.25 times respectively?