Basic rules of Mechanical Seals

Keeping mechanical seals safe is essential for their performance, reliability, and durability. Equipment conditions play a vital role in it.

The mechanical seals are designed with the objective to stop leakage of the fluid during the operations without limiting the amount of motion in the rotating parts.

They are installed onto the rotating shaft.

The two polished seal faces come into contact with each other. They are spring loaded to facilitate proper rotation.

One of the them is stationary and the other rotates along with the pump shaft.

The faces are sealed to the mounts by a secondary seal which is an O-ring in the majority of the applications.

What equipment conditions should you keep in mind to keep the mechanical seals good?

  • Never bent the rotating shaft more than a limit

Experts say that the maximum deviation that can be tolerated is .001 inches the maximum.

If the shaft crosses this limit, then the lapped surfaces do not remain together. It impacts the sealing.

  • Make sure the bearing doesn’t move axially

When its bearing supports the rotating shaft, you should ensure that the axial movement is not more than 0.005 inches.

If the shaft moves more than that, then the force pushes the seal faces together. Over-compression of the polished seal faces causes excessive wear and tear.

If the shaft moves in the reverse direction, then it may under-compress the sealed faces. It causes visible damage to the finishing and polish of mechanical seals.

  • Make sure the mounting surface is perfectly perpendicular to the shaft

It is another critical aspect that keeps your mechanical seal in the right condition.  The run-out of the shaft and the mounting surface should never exceed more than 0.005 inches of shaft diameter.

When the shaft is not perfectly perpendicular, then seals face excessive wear while rotating. Its spring mechanism, drive pins, and pads get damaged. Ultimately the mechanical seal conks off.

Mechanical seals always expect to have some shaft movement at high speeds. However, the shaft movement has to be the minimum to achieve the long life of a seal.

For optimum seal life, the shaft that runs must be limited to 0.002 inches when the rotating speed is 1800 RPM. Any shaft run more than that will damage the seal faces. It will hamper the life of the seal.

Call the sealing specialist to assess the damage if you aren’t much sure about it. He has a comprehensive checklist to troubleshoot the problem.

Leak-Pack is ISO 9001:2008 certified company and one of the best mechanical seals suppliers in India, providing solutions to all types of leakages by manufacturing Mechanical Seals and Sealing Components as per customer’s drawings, samples or requirements. To know more about Mechanical Seal call on +91-(2739) 271592 or email at

Also Read:

An Introduction to the Five Key Features of Good Mechanical Seal Design

How do Pump Seals Work?

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