Heat exchanger pressure testing issue

Generally, pressure is applied to the tube side; in some special cases, pressure needs to be applied to both sides. We use high-pressure water cooling, and during pressure application, it is the tube side that is pressurized. The water pressure is low, but leaks occur once the shell side starts operating, with the operating pressure on the shell side being over 70 kilograms. During this year’s maintenance, we pressurized both the tube side and shell side of the high-pressure heat exchange equipment.

For pressure testing of the tube side, blind flanges are typically installed at the inlet and outlet of the tube side. After filling the tube side with water, a pressure pump is used to raise the pressure to 1.25 times the operating pressure; if no leaks occur after maintaining this pressure for half an hour, the test is successful. If the operating pressure in the shell side is relatively high, it is also necessary to perform a pressure test on the shell side, by applying a pressure equal to 1.25 times the operating pressure.

If only the circulating water (tube side) is under maintenance, then only the pressure on the tube side needs to be adjusted； The premise is that the location of the repair has no relation to the shell side (no modifications to the cylinder or tube sheet, etc.), and it is a repair aimed at restoring the original design.

First, determine the type of your heat exchanger; the most common type nowadays is the tubular type, while the plate-type is also quite widespread. If an internal leak occurs in a heat exchanger, it is necessary to find a way to repair it. If an internal leak occurs in a shell-and-tube heat exchanger, pressure must be applied from the shell side; the end caps at both ends of the tube sheet on the tube side need to be removed in order to locate the point of leakage. If there is a leak at the junction of the tube sheet and the tubes, it must be rewelded. If there is a leak inside the pipe and fluid is flowing out, it means that section of the pipe is leaking and can no longer be used; it must be sealed (by welding or plugging). If it is a detachable plate heat exchanger, it needs to be disassembled for replacement or the plates need to be removed; whereas for a plate heat exchanger that is welded together, it has to be discarded. For the testing method section, any pressure level is acceptable. (For reference)

First, determine the type of your heat exchanger; the most common type nowadays is the tubular type, while the plate-type is also quite widespread. If an internal leak occurs in a heat exchanger, it is necessary to find a way to repair it. If an internal leak occurs in a shell-and-tube heat exchanger, pressure must be applied from the shell side; the end caps at both ends of the tube sheet on the tube side need to be removed in order to locate the point of leakage. If there is a leak at the junction of the tube sheet and the tubes, it must be rewelded. If there is a leak inside the pipe and fluid is flowing out, it means that section of the pipe is leaking and can no longer be used; it must be sealed (by welding or plugging). If it is a detachable plate heat exchanger, it needs to be disassembled for replacement or the plates need to be removed; whereas for a plate heat exchanger that is welded together, it has to be discarded. For the testing method section, any pressure level is acceptable. (For reference)

I won’t say more – we handle both the tube side and the shell side, with the principle of ensuring no leaks! ! ! ! If we don’t start work and miss the deadline, it won’t be just a matter of saving a little money

This post was last edited by Bai Ding on 2017-6-17 at 23:48. The pressure testing of the heat exchanger should be carried out three times. In the first round, the tube bundle is placed inside the heat exchanger shell and a pressure testing fixture is installed; at this point, both ends of the tube side can be seen. Water is then injected into the shell side to test for leaks in the tube bundle, and any leaks can be sealed easily if they occur. On the second attempt, install the small floating head and the tube side cap, then perform a pressure test on the tube side. For the third time, install the large hat and conduct a shell-side pressure test. Pressurize three times to 1.25 times the operating pressure, then hold the pressure for half an hour; no leakage is acceptable.