Material issues of components inside mechanical seals
Thread Content
Our factory’s high-temperature pump seals have been experiencing frequent failures recently, with the main issues being wear of the rotating and stationary rings as well as loss of elasticity in the bellows. I would like to ask what are the best materials currently in use? The temperature is between 250 and 350 degrees
First, please have the Maintenance Department take the lead in examining the stability of the process operations to determine if there are any signs of instability. Next, it is necessary to consider the manufacturers of mechanical seals – whether products from domestic manufacturers with strong capabilities can be used (of course, proper assembly by the maintenance team is also essential). It’s also important to get feedback from these seal manufacturers. If necessary, the Logistics Department can contact the manufacturers to arrange for on-site installation. Of course, it’s first necessary to tidy up our own facilities. The brands we use include John Crane, Sichuan Nikki, and Huayang; please choose one yourself.
After saying so much, they still didn’t explain the reason to the original poster
Does your medium contain solid particles?
The bellows have lost their elasticity! ? If it’s not clogged, then the material chosen is incorrect; ordinary stainless steel wave plates cannot be used at such high temperatures. If there is no corrosive environment, AM350 should be used instead
High-temperature pumps require cooling water; if the bellows lose their elasticity, check whether it is caused by scaling! Is the water you use suitable? Severe wear of the rotating and stationary rings is mostly caused by the material of these rings! You can consult the sealing manufacturer and ask their technical department to analyze the temperature and solid content of the medium, so that they can customize the stationary and rotating rings for you!
Given the frequent occurrences of leakage and fire incidents in high-temperature pumps at many refineries these days, I recommend using a tandem sealing arrangement, specifically the 32+53A or 11+53A configuration. This will ensure the safety of the equipment even if the seal in the preceding stage fails. Secondly, there are many reasons for the wear of the sealed surface; for example, the medium may contain particles, high compression levels, or scaling caused by cold water, all of which can cause the sealed surface to be damaged. The common reasons for the failure of bellows include: failure due to high temperatures, deformation under high pressure, and scaling from cold water that blocks the gaps in the bellows. The specific reasons require a detailed industrial analysis.
I think you could use a spring-type moving ring, and try using high-temperature resistant silicon nitride for the friction pair
At such high temperatures of the medium, if the amount of cooling water is low, it is easy to damage the seal of the machine. It is recommended that the poster check the temperature of the mechanical seal. Next, I will introduce the structure of the mechanical seal, as well as the materials of the friction pairs and the types of media used. That makes it easier for everyone to analyze.