How to Do Mechanical Seal Setting Compression

Setting Seal Compression

To set mechanical seal compression properly, follow these steps:

1. Consult the seal installation instructions and pump manual for specs on required compression, spring type and orientation, and installation procedure. Note the compression distance.
2. Inspect the seal components for any damage and clean them. Inspect the shaft and seal housing bore for damage, runout and concentricity. Address any issues before proceeding.
3. Install the stationary part of the seal in the seal chamber bore. Make sure it is fully seated and secured.
4. Lubricate the shaft and slide the rotary part of the seal on. Don’t damage the seal faces. Clamp the seal body to the shaft.
5. Tighten the rotation clamp properly to prevent movement between the seal body and shaft.
6. Install the setting plate and hold it perpendicular to the shaft. Ensure it is up against the seal body fully.
7. Loosen the seal gland bolts, then carefully push the seal gland towards the setting plate. Use an even force to avoid cocking the gland.
8. Using a feeler gauge or vernier caliper, measure the gap between the gland and seal housing. Adjust until the desired compression distance is achieved.
9. Tighten the gland bolts gradually in a star pattern while maintaining the compression gap. Periodically recheck the gap while tightening.
10. Once the gland bolts are fully tight, remove the setting plate and rotate the shaft by hand a few turns. Verify there is no shaft binding.
11. Prior to pump start-up, ensure the gland bolts remain fully tight and the compression distance is still correct. Make adjustments if needed.

Factors Affecting Seal Compression

• Seal design: The type of seal (e.g. cartridge, component, balanced, unbalanced) and the materials used affect the required compression. Consult the seal manufacturer’s specifications.
• Process conditions: The temperature, pressure, and chemical properties of the sealed fluid impact seal compression. Higher temperatures and pressures generally require greater compression to maintain a tight seal.
• Shaft speed: Faster shaft speeds generate more heat and require more compression to keep the faces in contact. However, excessive compression at high speeds can cause thermal distortion of the faces.
• Equipment condition: The condition of the pump and shaft, including shaft runout, end play, and alignment, affects seal compression. A misaligned or wobbling shaft prevents even compression.
• Environmental factors: Ambient temperature, humidity, and contaminants can impact seal materials and compression. Dust, dirt or chemical fumes may degrade the seal faces or spring.