Seal performance – Top Tips

Getting the best performance from your engineered mechanical seals can be challenging.

Mechanical seals have a working life after which they must be re-engineered/repaired or, in the case of smaller/low-cost seals, replaced.  With experience across all major mechanical seal brands, NASH has an unrivalled knowledge-base.

Seal Performance Top Tips from NASH

Here are our top tips to help get the best performance from your mechanical seals.  Maximising seal performance also delivers the longest working life.

  1. Check shaft alignment.  Prior to installing mechanical seals, measure and record shaft run out at more than one position. This will check for radial or angular misalignment, stuffing box squareness and concentricity. Check alignments are within the manufacturers’ guidelines. If no guidelines are available, work to <0.1mm for shaft diameter >50mm and <0.05mm for shaft diameter <50mm.
  2. Tighten all drive screws.  Ensure all drive screws are fully tightened to recommended torque values and remove any setting clips, or secure them out of position, before shaft rotation
  3. Flush out pipework.  Make sure the support system and pipework are properly flushed out when installing double mechanical seals. This ensures the seal will be presented with clean barrier/buffer fluid. Also, when filling with fluid, ensure that the seal, pipework and any instrumentation are vented and bled thoroughly prior to start-up.
  4. Some initial squealing is normal. High pitched squealing can occur during initial operation of dry running seals with SiC v Carbon faces (particularly on dry, dehumidified nitrogen). Once the carbon starts to bed in, it will lay down a transfer layer on the SiC face and the squealing will stop. This can take hours or days depending on the application.
  5. All mechanical seals leak.  Remember that all mechanical seals leak: they have to. Seal faces require a stable fluid film between them to ensure adequate lubrication to reduce friction and wear. Actual leakage rate will depend on the seal type, size and duty conditions.
  6. Diagnose any failure.  Don’t simply swap a failed seal. Find the root cause of seal failure before fitting a replacement – mechanical seals rarely just fail. Surveys show that around 65% of seal failures occur because of plant upsets, changes and operational issues.

Here to help

There are innumerable reasons why mechanical seals fail and sometimes, failure occurs much sooner than it should. This leads to unnecessary downtime and expense. We hope our top tips give you some pointers but if you would like to discuss how NASH can help you get the best and longest performance from your engineered mechanical seals, get in touch