Heat Exchanger Inspection

Performance Monitoring

• Calculate U value: Measure inlet and outlet temperatures and flow rates on both sides. Calculate the actual U value. Compare to the design U. A 20% drop indicates fouling.
• Monitor approach temperature: The difference between hot outlet and cold inlet temperatures. Increasing approach means decreasing efficiency.
• Monitor pressure drop: Increasing pressure drop on either side indicates fouling or blockage. Compare to baseline.
• Check for cross-contamination: Sample the cold fluid for traces of the hot fluid. If present, tubes or plates are leaking.

External Inspection

• Visual check: Look for external leaks at flanges, gaskets, and casing. Check for corrosion, paint damage, and insulation deterioration.
• Check for vibration: Excessive vibration indicates tube bundle looseness, flow-induced vibration, or support failure.
• Check connections: Verify all instrument connections (temperature, pressure) are functional and calibrated.
• Inspect insulation: Damaged insulation causes heat loss and can allow water ingress, causing external corrosion.
• Check supports: Verify the exchanger is properly supported. Thermal expansion must be accommodated by sliding supports.

Internal Inspection (Annual)

1. Isolate, drain, and lock out the exchanger.
2. Remove covers or pull the tube bundle (shell and tube type).
3. Inspect tube surfaces for scale, corrosion, and pitting. Use a borescope for inaccessible tubes.
4. Inspect the shell side for deposits, corrosion, and baffle damage.
5. Check tube-to-tubesheet joints for leaks. Hydrostatic test if necessary.
6. Inspect gaskets and replace if degraded.
7. For PHE: inspect plates for cracks, distortion, and gasket condition.
8. Measure tube wall thickness at suspect areas. Replace tubes with significant thinning.
9. Clean fouled surfaces. Use chemical cleaning for scale, mechanical cleaning for sediment.
10. Reassemble, pressure test, and record findings in the maintenance log.