Can the materials of the stationary and rotating rings in a mechanical seal be the same?
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The new mechanical seal is just for show; images 2 and 3 show the mechanical seals of the vertical multi-stage centrifugal pump. They have been repaired many times yet still leak. An experienced technician suspects that the issue lies in the fact that the materials of the stationary and rotating rings of the mechanical seal are the same
As a supplementary note, the medium is extraction water, and it doesn’t seem to be very clean
The materials of the stationary and rotating rings can be the same, but generally graphite is used against silicon carbide – one being soft and the other hard, with the hard ring having a wider surface area.
The medium contains impurities； Particles are usually paired using a hard/hard combination in friction pairs
A reasonable flushing plan must be adopted!
Is the end face of the removed mechanical seal worn?
Under normal circumstances, the medium used with this pump is fine. It has been in use for three months since we carried out its major repair, while the other unit has required repairs five times over the past half month; it still leaked when put into operation yesterday, and the leakage reduced after 20 minutes of operation. It says there is no leakage in the hydrostatic test, but there is leakage when the turbine is turned manually. The mechanical seal uses the same material for both the stationary and rotating rings; a wide-faced stationary ring is currently in use, and now there is consideration to switch to a multi-spring mechanical seal. There were intermittent noises at the site, but the sound quality through the listening device was good.
The leader suspects that the noise is caused by loose coupler bolts
The end-face pressure distribution in a single-spring mechanical seal is uneven, leading to easy leakage; with multiple springs, the distribution becomes much more even! What is the compression amount of the mechanical seal? What is the axial play of the pump? A mechanical seal can normally last for three years; three to five months is far too short!
To correct that, it was repaired three times in one week. The problem has now been identified; it turns out that the sealing surfaces of the two new mechanical seal static rings are deformed, which is a issue with the accessories. We have very high standards regarding odors; any leakage must be addressed immediately. There is significant pressure to meet environmental regulations, and the company aims to become a chemical plant with zero leaks.