The ammonia liquid pump, of the centrifugal oil pump model 80AY100x2, experiences frequent leaks due to its bellows mechanical seal
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The pump outlet pressure is 1.8 Mpa; the seal used is the DBM-65 seal made of alloy against graphite. The cooling water used is fresh water. Leakage occurred in the seal after it had been in operation for about 2 months. Could you experts please advise on how to resolve this issue?
There are many types of seal leakage issues: whether it has been opened, what the condition of the sealing surfaces and O-rings is like, and whether there are any impurities present
You’re asking how to fix a seal leakage, right? Well, it’s necessary to locate the point of leakage. The DBM-65 bellows mechanical seal has 5 sealing points: 4 static sealing points, where the gaskets or bolts may not be tightened properly; and 1 dynamic sealing point, resulting from wear of the sealing surface. In such cases, grinding paste can be used on a grinding platform to carry out repairs. Severe wear requires replacement with a new seal. There are many reasons for seal leakage; cooling the seal with fresh water over a long period of time can cause scaling on the surface of the seal ring, leading to wear of the sealing surface. It can be switched to desalinated water for cooling to prevent scaling on the seals, or scaling can be removed every half month by using tank acid. Furthermore, different media have varying temperature and viscosity requirements, and the conditions under which sealing is compromised also differ. For high-temperature media, cooling methods such as hot water cooling, steam cooling, or high-temperature sealing oil can be used. A sealed flushing scheme can also be used to improve the quality of the sealed operating environment. Please provide photos of the seal damage on this pump, as well as information on the medium’s temperature and viscosity, along with the current flushing method being used; I’ll help you improve it
The mechanical seal of the amine liquid pump in our company’s sulfur workshop has a short service life. The original seal used small springs; later, the seal manufacturer was asked to modify it so that larger springs were used. However, it’s not clear what material the friction pairs are made of – they seem to be designed for direct contact
A mechanical seal is a type of equipment that requires dynamic management; the tightening force should not be too great at once, as it needs to be adjusted as leakage occurs. Mechanical seals are inherently capable of having some level of leakage, and standards such as GB50275 specify requirements regarding leakage levels.
Has it been disassembled or repaired before? The reasons for leakage after repair and installation are different from those of the original unit. The information is not specific, so it’s impossible to make a definite determination
Bellows mechanical seal DBM series
Yun has been running for several months without any issues
Our company also uses large springs, made of an alloy with silicon carbide. The performance is okay, I guess.