There are many types and models of bellows mechanical seal, which can be divided into cartridge mechanical seal and non-cartridge mechanical seal according to whether there is shaft sleeve or not. And it can be divided into two types according to the seal structure: one is that the moving ring adopts bellows component; the other is that the static ring adopts bellows component. The general selection methods are: ① select mechanical seal according to the nature and operation conditions of the conveying medium; ② select mechanical seal according to the pump specification and model; ③ select mechanical seal according to the specific pressure of the end face and the relative movement speed of the end face.
As far as materials are concerned, nickel chromium stainless steel, nickel chromium molybdenum alloy and high nickel alloy steel are used for bellows, which have the advantages of high hardness, high strength, high wear resistance, corrosion resistance, high temperature resistance and small thermal expansion coefficient.
For friction rings, impregnated resin graphite, impregnated metal graphite, silicon tungstate, silicon carbide and cemented carbide are used. They have good thermal conductivity, self-lubricating performance and corrosion resistance in sulfuric acid, hydrochloric acid and alkali.
The sealing ring adopts "O" ring, which has good elasticity and sealing performance, and has the properties of non viscosity, non dissolution, non aging, high temperature resistance and low temperature resistance. The material mainly includes nitrile rubber, fluororubber, etc.
The use of rubber bellows mechanical seal
In the oil and gas production equipment of the shallow cooling unit of the Laer Compressor Station, a large number of bellows mechanical seals are used. Only the correct use and operation can ensure the normal operation and extended service life of the mechanical seal.
(1) Before start-up, check the mechanical seal for leakage. If there are many leaks, find out the causes and try to eliminate them, or dismantle, check and reinstall them. Rotate the turning gear according to the direction of the pump to check whether it is light and even.
(2) Before starting, keep the sealing cavity full of liquid, and turn it to prevent the sealing damage caused by sudden starting.
(3) During the operation of the pump, the pressure of the pump shall be stable and the phenomenon of evacuation shall be avoided.
At present, Sealcon has developed and used a variety of bellows mechanical seals, which have good sealing performance and long service life. It has been widely used and achieved remarkable results.