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What are the installations and preparations for mechanical seals?
May 10, 2018

What are the installations and preparations for mechanical seals?

Preparation and installation precautions before installation of mechanical seals

Check that the type and specification of the mechanical seal to be installed are correct and the quality meets the standard.

 Check whether the components of the mechanical seal are damaged, in particular whether the sealing surfaces of the moving ring and the stationary ring are damaged. If it is found to be damaged, it is necessary to enter the mechanical seal to repair or replace the new one. The sealing elements need to be cleaned with gasoline or kerosene to keep the surface of all components free from dust and foreign matter.

 Check the liquid sewage pump shaft or bushing surface and the inner wall of the seal chamber, seal the inner surface of the cover if there are burrs, groove marks. If burrs or groove marks are found, they should be smoothed, polished, and cleaned with gasoline or kerosene. Keep them clean and free from dust and debris on the surface. Do not scrub the ring and the surface of the static ring with a mechanically impervious cloth or cotton gauze. Use a clean, soft gauze, absorbent cotton, or the like.

 The assembly process should be kept clean to ensure that the sealing surfaces of the moving and stationary rings are not scratched or broken. To facilitate loading, oil should be applied to the surface of the shaft or bushing, the surface of the gland and the seal ring during assembly, and the oil should be applied to the sealing surfaces of the moving ring and the stationary ring to prevent dry friction from starting immediately.

 The impregnated graphite ring should be tested before installation, and the hydrostatic pressure should not be less than 1.5 to 2.5 times the working pressure. Water beads and sweating should not occur on the outer surface of the graphite ring. If the above experimental conditions are not available, an assembly static pressure test can be performed before the start-up of the seal installation to identify the degree of pressure resistance of the graphite ring. The end of the anti-rotation groove at the end of the static ring and the top of the anti-rotation pin should maintain an axial clearance of 1~2mm to avoid buffer failure.

 The mechanical seal of the coiled spring structure should be installed with the same direction as the shaft rotation. If the direction is incorrect, the seal will fail. If a single spring structure type 103 mechanical seal is divided into two kinds of left-handed and right-handed, special attention should be paid to the mechanical seal of the front and rear of the pump in the installation. The direction of the spring rotation is different. If the direction of rotation of the pump shaft is neglected during installation, the mechanical seal is likely to be reversed and the front and rear mechanical seals are inoperative.

 The piping system connected to the equipment must also be cleaned. If the debris of the system is not cleaned in time, the debris may enter the seal after long-term operation, thereby affecting the life of the seal. Most of the premature failure of new equipment seals is due to this reason, so it is necessary to set filters at the entrance of new equipment before driving.

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