Boiler and Heat-Exchanger Tube Inspection: Choosing the Examination

Separate the inspection questions

Determine whether the concern is wall loss, a crack, local erosion, deposits or another condition. A technique that screens for wall changes may not characterise every flaw orientation. Identify whether the result is intended to rank tubes, estimate remaining wall or support an engineering investigation.

Review previous leak locations and plugged-tube records alongside the inspection history. Keep the distinction between measured damage and a suspected mechanism that still needs confirmation.

Match the method to material and access

Conventional eddy current is widely used for suitable heat-exchanger tubing; other electromagnetic arrangements or ultrasonic techniques may suit different materials and objectives. Confirm the actual probe’s capability on the tube configuration rather than treating these methods as interchangeable.

Access, cleaning and probe travel affect coverage. Supports, tube ends, bends and obstructions can complicate interpretation or leave regions unexamined. Agree how those areas will appear in the report before quoting a percentage of tubes inspected.

Make the tube map the common reference

Use a verified tube numbering system and retain it across campaigns. Link each result to its tube, examined length, procedure and relevant limitations. Record follow-up examinations and the owner’s plugging or repair decision separately. A wall-loss estimate should not be presented as an automatic remaining-life calculation without the necessary engineering inputs.

References and next steps

ASNT’s electromagnetic testing overview provides further background. Use the governing specification and approved procedure for the actual job.

Discuss the examination scope. Include the component, material, service history and decision the inspection needs to support.