Failure and Judgment of Pump Mechanical Seal Failure

Mechanical seals, also known as face seals, are primarily used for the sealing of rotary shafts of pumps, compressors, hydraulic drives, and other similar devices. It is a sealing device made up of a pair of plane or pair of plane friction pairs consisting of a moving ring and a stationary ring. Pump mechanical seal refers to the device that is installed in the pump equipment and plays a role in dynamic sealing. It is one of the mechanical base components with sophisticated and complicated structure and is a key component of the pump machinery. Pumps have a wide variety of mechanical seals.

According to the model is mainly divided into light mechanical seals, medium mechanical seals, heavy mechanical seals, cartridge type mechanical seals. This paper mainly analyzes the causes of leakage of mechanical seals used in centrifugal pumps and their failure judgments. Mechanical seals for pumps usually consist of moving rings, stationary rings, pressure elements and sealing elements.

In daily maintenance, according to the disassembly of the mechanical seal, static seal surface wear marks, can help us analyze the sealing device after a variety of failures on the sealing surface caused by various abnormal damage. So depending on the phenomenon, find out the reason.
(1) no wear marks on the sealing surface
Cause:
1) Sealing bellows or springs and other compensation mechanisms skid, resulting in seals
No adhesive on the surface;
2) Sealing bellows or springs and other compensation mechanisms are blocked, resulting in no sealing of the sealing surface.
(2) Widening of the wear scar on the sealing surface
Cause:
1) The pump shaft is bent and deformed;
2) bearing damage, pump shaft vibration;
3) pump cavitation vibration;
4) Misalignment of pump and associated motor couplings;
5) Sealed static ring tilt.
(3) Narrowing of the wear scar on the sealing surface.
Cause:
1) The pressure in the pump is too high, resulting in deformation of the sealing surface;
2) The temperature inside the pump is too high, causing the sealing surface to deform.
(4) The sealing surface has no wear marks but bright spots
Cause:
1) The pressure in the pump is too high, which causes the sealing surface to warp and deform, causing no bright spots on the friction surface.
2) The contact surface between the seal gland and the pump seal body is rough or the seal gland is not tightened.
(5) The sealing surface has a trim
Causes: After the pump is evacuated and gasified, the seal ring or static ring is broken.