Questions regarding the expansion jointing process for tube sheets and heat exchange tubes?

Thread Content

I have some questions: 1. According to 8.8.1.2 in GB/T151, for strength expansion joints, an expansion process test should be conducted prior to expansion to determine the appropriate expansion degree. For 6.6.1.2, where the design pressure is greater than 4.0 MPa and strength expansion jointing is required, an expansion jointing process test shall be conducted, and the pulling force for the connection between the heat exchange tubes and the tube sheet must meet the requirements of 7.4.7. So, for strength expansion joining combined with seal welding where the design pressure is less than 4.0 MPa, what inspections should be carried out in the expansion process test? Such as pulling force, hydrostatic testing, etc. 2. In GB/T151, the allowable deviation for the diameter of the tube plate holes in 6.5.1.7 can be relaxed appropriately; however, the maximum gap between the tube plate holes and the outer diameter of the heat exchange tubes must not exceed the requirements specified for steel grade II tube bundles. Which requirement should be referred to here? 3. For the post-expansion inspection, what is the inspection ratio? If we do 100% inspection, it’s too much. I would like to thank all of you first.