SNS-VN

Root Cause Analysis of Mechanical Seal Failures: Reading the Evidence on the Faces

Replacing the seal with a new one without finding the cause of the failure often leads to the next failure. Root cause analysis turns each incident into data to improve long-term reliability, rather than just fixing the symptoms.

Step 1: Preserve the scene

Before disassembling, take photos and record the state of leakage, temperature, vibration, and operating parameters. Do not clean the seal and gasket faces, as the marks on them are evidence.

Step 2: Collect operating information

Ask operators about recent changes: flow rate, pressure, temperature, change of medium, sudden start or stop, previous maintenance. Many failures are related to operation outside the pump's design range.

Step 3: Visual inspection

  • Heat checking or thermal cracking on the hard face: suggests dry running or loss of fluid film.
  • Uneven wear on one side: may be due to shaft misalignment or vibration.
  • Deeply worn grooves and deposits: usually due to solid particles or medium crystallization.
  • Hard, cracked, or swollen gaskets: gasket material not suitable for temperature or chemicals.
  • Porous or blistered carbon: usually due to medium evaporation within the carbon or excessive heat.

Step 4: Analyze cause groups

Operation outside the design range, incorrect installation, unsuitable material selection, poor auxiliary system operation, vibration due to bearing or alignment, and hang-up when moving parts cannot compensate for displacement.

Step 5: Verify hypotheses

Compare marks with operating data, review pump and auxiliary system parameters. If still unsure, samples can be sent to the manufacturer for in-depth analysis.

Step 6: Corrective action

  • Correct the root cause before running again.
  • Update installation and inspection procedures.
  • Consider upgrading the seal configuration or auxiliary scheme if the failure recurs.
  • Monitor the effectiveness after changes.

Note

Record the results of each analysis to build internal knowledge. Contact SNS-VN if analysis support is needed.

Reference

Compiled from common mechanical seal maintenance practices.