The problem of mechanical seal failure
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Hello everyone, I’m a newcomer and this is my first time asking questions here. I hope someone can help me, and I would like to express my gratitude in advance. Our facility has a refrigeration compressor unit that includes a gear pump; the medium used is ammonia and oil. Some time ago, due to a leakage in the mechanical seal (which had reached the end of its useful life), the mechanical seal was replaced. After the replacement, a test run was conducted at room temperature; two to three minutes later, the mechanical seal started leaking, resulting in a large amount of material leakage. Upon disassembly, it was found that the rotating ring of the mechanical seal had cracked entirely along the axial direction, with the crack width being approximately 2–3 mm. After replacing it again and testing the vehicle, this phenomenon occurred once more. Since the machine needed to be restarted urgently the next day, a new pump had to be installed. At the time of the leak, the pressure did not reach that of normal operational conditions, the compressor was not running, and the temperature of the medium was at room temperature. Note: This mechanical seal is a multi-spring mechanical seal, with the friction pair made of graphite against graphite. Everyone, please help me figure out what the reason is. Thank you all:handshake
This situation is relatively rare; if there are no issues with assembly, try changing the material of the moving ring friction pair.
Thank you to the person above. Are there any other potential issues with the assembly apart from the spring compression? The machine workers in my workshop have many years of experience in installation, and according to them, there is no problem with the compression level. This new mechanical seal was manufactured by Beicarbon Surveying and Mapping; they made it before as well, and no problems occurred. The mechanics and supervisors in my workshop also can’t figure out what might be causing this problem; they all have many years of experience. Could anyone help me think of other possible explanations? Thank you
It might be a problem with the shaft runout of the pump; you can check the bearings of the pump. After installing the mechanical seal, use a dial indicator to check it. If a mechanical seal with an integral bellows is used, it may be able to support shaft runout for some time, while multi-spring types tend to drift. The mechanical seal for the overall bellows is more expensive.