Pressure testing upon startup of the heat exchanger

Pressure testing of heat exchangers (1) – Pressure testing of floating-head heat exchangers. The pressure testing of floating-head heat exchangers is carried out in three stages. In the first stage, the connections between the fixed tube sheet, the floating tube sheet, and the tubes are tested (water is filled in the shell side). The specific procedure is as follows: A. Place the gaskets between the tube bundle and the shell at the flange sealing surfaces. B. Use a tube extractor to push the tube bundle into the housing. C. Install the test fixture on the floating head side, and fix the heat exchanger pressure testing ring on the tube sheet side. D test pressure: Depending on the condition of the equipment, the test pressure is 1.1–1.25 times the maximum operating pressure. Second stage: Pressure testing of the tube sheet and floating head (water filled in the tube side). A. Reinstall the tube sheet and floating head end caps. B. Fill water from the tube box. C. The test pressure shall be 1.25 times the working pressure; maintain this pressure for 30 minutes, then reduce it to the maximum working pressure and hold it there for 10 minutes. No leakage is considered acceptable. The third step involves pressure testing the shell and the outer cover, with the aim of checking the seals between the shell, the fixed tube sheet and the shell flanges, as well as between the flanges of the outer cover and the shell. The specific procedures are as follows: A. Reinstall the outer cover. B. Fill water through the shell flange. C. The test pressure shall be 1.25 times the working pressure; maintain this pressure for 30 minutes, then reduce it to the maximum working pressure and hold it there for 10 minutes. No leakage is considered acceptable. During this pressure testing phase, it is advisable to maintain the pressure in the pipe bank for the second pressure testing stage at the operating pressure, in order to protect the connections between the fixed tube sheet and the tubes and prevent new leakage points from appearing on the tube sheet. (2) Pressure testing of U-tube heat exchangers: The pressure testing of U-tube heat exchangers is carried out on both the shell side and the tube bank side. A. Purpose of shell-side pressure testing: To inspect the connections between the tube sheet and the tubes, to check the sealing between the tube sheet and the shell flanges, and to test the strength of the pressure vessel shell. The specific procedures are as follows: a. Reinstall the sealing rings and U-tube bundles. Before reinstalling the steel ring, it is necessary to carefully inspect the sealing surface of the trapezoidal groove and thoroughly clean it, ensuring that no debris remains. When cleaning the trapezoid, it is necessary to protect the sealing surface from being scratched, especially to prevent radial scratches that could lead to seal failure. If the sealing surface already has grooves, it can be surfaced by TIG welding and then polished smooth by a fitter. If the base material is a Cr–Mo class heat-resistant steel, special attention should be paid to whether welding repairs could cause cracks, and a comprehensive welding repair plan should be in place. b. Pressure rings for side-mounted pressure testing of the tube bundle shell. The shell-side hydrostatic test pressure is 1.1 to 1.25 times the maximum operating pressure. The shell-side pressure testing process is also a way to inspect the welds connecting the tube sheet to the tubes; the tube ends should be carefully checked, and any leaking tubes or tube ends must be eliminated. B. Purpose of pressure testing the tube side: To check the seal between the tube box and the tube sheet, as well as to test the strength of the tube box pressure vessel. The specific procedures are as follows: a. Reinstall the gaskets (seals) and the tube box. Similarly, before reinstalling the tube box, the sealing surfaces must be carefully inspected to ensure they are clean. b. Voltage boosting. The test pressure is 1.25 times the highest operating pressure in the tube side. (3) Pressure testing of fixed-tube-sheet heat exchangers: The hydrostatic testing of fixed-tube-sheet heat exchangers is similar to that of U-tube heat exchangers; it involves testing both the shell side and the tube side as well. However, it is simpler – no pressure rings are needed for testing the shell side, and strength testing can be carried out directly by introducing water into that side.

Hello! May I ask what standards are used for the pressure testing of your heat exchangers? There should be relevant standards for pressure vessels or the petrochemical industry, right? Could you share them with me?