Common Failures and Maintenance Guide for Metal Bellows Expansion Joints｜Key to Ensuring Equipment Safety and Longevity

In various industrial piping systems, metal bellows expansion joints play a vital role in absorbing thermal expansion, compensating for pipeline displacement, and reducing vibration and noise. However, if proper installation, inspection, and maintenance are neglected during long-term use, issues such as leakage, rupture, and corrosion may occur, compromising system stability.

This article introduces the most common failure types of metal expansion joints, their causes, preventive measures, and daily maintenance practices — helping users extend service life and reduce maintenance costs.

1. Common Failure Types and Cause Analysis

1. Bellows Rupture

• Possible Causes:

  • Overload fatigue: Excessive compensation beyond design limits

  • Installation misalignment or lack of guides

  • Frequent vibration from pumps or fans

  • Corrosive media attacking metal surfaces

2. Weld Leakage

• Possible Causes:

  • Poor welding during installation

  • Fatigue cracks over time

  • Misaligned inner sleeve causing direct impact on welds

3. Flange Sealing Failure

• Possible Causes:

  • Improper bolt tightening sequence causing uneven stress

  • Incompatible gasket material

  • Frequent thermal expansion and contraction loosening bolts

4. Thrust Causing Equipment Misalignment

• Possible Causes:

  • No limit structure in design

  • Lack of fixed or guide supports

  • Incorrect installation direction, causing unbalanced internal pressure thrust

2. Daily Maintenance & Care Recommendations

✅1. Regular Inspection System

• Check appearance for deformation or cracks at least once a month

• Inspect flanges, bolts, and welds for looseness or leakage

• Ensure supports and limit devices are intact and functioning

✅2. Operate Within Proper Working Conditions

• Always run within rated temperature, pressure, and movement ranges

• Avoid rapid temperature changes that cause thermal shock

• Use corrosion-resistant materials such as SS316L or Inconel for harsh media

✅3. Installation Best Practices

• Follow compensation direction strictly based on drawings

• Never use the expansion joint as a load-bearing point

• Keep bellows in natural length during installation — no stretching or compression

✅4. Replacement & Emergency Handling

• Immediately shut down and replace the joint if cracks or rupture are found

• Temporary flexible hose connectors can be used in emergencies

• Contact the manufacturer for technical support if needed

3. Tips to Extend Service Life