Heat exchanger leak detection
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Our company has a refrigerant coil condenser for a York chiller; the shell side uses R22, while the tube side utilizes circulating water. The tubes are made of copper, and the tube sheet is of the strength-expansion type. Some time ago, an operator accidentally introduced something into the circulating water, which caused corrosion of the copper pipes. The pipes were replaced, but problems persisted. As per the regulations, the system was pressurized with nitrogen to 15 kilograms to check for leaks; no bubbles in soapy water were detected on either side of the tube sheets, nor in the tubes themselves. However, after 24 hours, the pressure dropped by 2.5 kilograms, and after 7 days it had fallen to 8 kilograms. Vacuum pumping could only achieve a pressure of 600 Pa – no lower than that. At first, there was suspicion that the tubes might be problematic, but they have undergone full ultrasonic testing, so there should be no issues! Now, out of desperation, I want to use a helium mass spectrometer for leak detection. Does anyone know how to proceed? If helium is the only gas that can be used for leak detection, what should I do? ?
HG 20584 specifies the specific methods for helium leak detection. Helium leak detection has very high sensitivity; it’s likely to fail.
Thank you so much. I knew that the helium test wouldn’t pass, but my goal wasn’t to pass that test; instead, I wanted to find the leaks in the heat exchanger so that it could be repaired. It would be a shame to discard the heat exchanger just because of such tiny leaks that cannot be detected
Good employee. But you need to be careful; copper pipes expand mechanically, so pay attention to the expansion rate during maintenance and avoid creating cracks at the expansion grooves
Was leak testing with soapy water done again after 24 hours and 7 days?
This post was last edited by xlxuiin on 2015-12-3 22:55. The problem lies at the flared area. What is the thickness of the copper tube? Poor expansion joining of the copper tube can lead to tube cracking and separation. http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=920024&highlight=%CD%AD%B9%DC%2B%D5%CD%BD%D3
Generally, grooved expansion joints provide better sealing performance. Since there is no issue with the heat exchange tubes, a hydrostatic test should be conducted on the expansion joints to check for any leaks; alternatively, compressed air can be used for leak detection. Using helium for leak detection is too costly and dangerous, so it’s not necessary.
Bro, I really don’t know what to say anymore. I’ve already explained it clearly – my biggest problem right now is that I can’t locate the leak in either the soapy water test or the nitrogen leak detection method. I’ve tried it many times, but the air is still leaking slowly
It’s difficult to determine exactly which tube is leaking using helium; it is recommended to use ammonia testing instead. You can also use soapy water for a leak test; even in cases of severe leakage, the source of the leak can be identified. A PT permeation inspection tube sheet will also work, but it’s quite troublesome to clean the surface properly. There are also many new technologies such as IRIS and the acoustic eye method. . . Different testing methods have different levels of accuracy; the one that suits one’s own needs is the best.