Installation Errors Leading to Seal Failure
Mechanical seals are complex instruments with many parts. They operate across numerous industries and are often required to perform in extreme environments where harsh chemicals, extreme temperatures and pressure differentials, and other forces can challenge even the most robust mechanisms.
Seals can fail for a multitude of reasons. Inevitably, however, nearly every seal failure is caused by human error. From design to installation, maintenance, and operation, a seal is ultimately nothing more than a sum of the efforts and decisions of those who create it and put it into use. A tiny miscalculation, shortcut, or deviance from known parameters is likely to adversely affect performance and/or durability.
In this series of articles, we’ll take a look at the most common errors that lead to seal failure, beginning with mistakes that happen during installation.
Improper Face Loading
- Excessive or insufficient compression of the seal faces can lead to uneven wear, overheating, or inadequate sealing.
- Incorrect spring tension adjustment can also cause the seal to fail prematurely.
Incorrect Shaft Preparation
- Burrs, scratches, or contaminants on the shaft or sleeve can damage the seal during installation or compromise the sealing surface.
- A shaft that is not cleaned properly can introduce debris into the seal assembly.
Seal Orientation Issues
- Installing the seal components in the wrong orientation, such as reversing the rotating and stationary faces, can prevent the seal from functioning as intended.
- Failure to align the seal faces correctly can result in leaks or uneven wear.
Proper Lubrication
- Some mechanical seals require lubrication during installation to avoid damaging the faces or elastomers. Others are “dry” seals that should not be lubricated.
- Using the wrong type of lubricant (or lubricating a dry gas seal) can lead to material degradation or poor seal performance.
Over-Tightening or Under-Tightening Bolts
- Over-tightening bolts can distort the seal housing or faces, while under-tightening can lead to improper compression and leaks.
- Uneven tightening of bolts may create stress points, causing misalignment or seal failure.
Incorrect Seal Size
- Using a seal that is too large or too small for the shaft or housing can result in poor fitment, leaks, or excessive wear.
- Incorrect seal dimensions can also lead to instability during operation.
Failure to Follow Manufacturer Guidelines
- Skipping or misinterpreting the manufacturer’s instructions, such as recommended assembly sequences or torque specifications, can cause installation errors.
- Neglecting to check for specific environmental or operational requirements can also lead to issues.
Misalignment with Adjacent Components
- Misalignment between the pump, motor, and coupling can create excessive vibrations, which can damage the seal over time.
Incorrect Handling of Seal Components
- Mishandling seal parts, such as dropping or scratching the faces, can compromise their integrity.
- Improper cleaning of seal components can leave residues that interfere with performance.
Elastomer Damage During Installation
- Pinching, cutting, or improperly stretching O-rings, gaskets, or other elastomers can lead to leaks or reduced seal life.
Avoiding Failure
When installing a mechanical seal in any industrial context, it is important to follow best practices. These will vary case by case, but there are certain practices that are always wise to follow, including:
- Always thoroughly inspect all components before assembly
- Use the correct tools and adhere to manufacturer guidelines
- Ensure all parts are clean, intact, and lubricated as required
- Verify that the seal matches the application specifications
By following best practices and manufacturer guidelines, you can’t always guarantee a seal won’t fail. But it can guarantee that, if it does fail, it won’t be because of you.
