Why inspect heat exchangers
Heat exchanger tubes suffer corrosion, erosion, pitting, baffle wear and cracking. A single leaking tube contaminates fluids, reduces efficiency and can stop the unit. Periodic inspection lets you plug or replace tubes before failure and plan the next shutdown with data.
Main damage mechanisms
Internal and external corrosion, localised pitting, inlet-end erosion, vibration wear at supports and baffles, stress corrosion cracking and fouling that accelerates attack. Each mechanism favours a different technique.
Technique by tube material
| Tube material | Recommended technique |
|---|---|
| Carbon steel / ferromagnetic | Remote field testing (RFT) |
| Stainless, brass, copper-nickel, titanium | Eddy current (ECT) |
| Finned tubes (air coolers) | Near field testing (NFT) / IRIS |
| Any material, thickness measurement | IRIS (ultrasonic) |
Inspection steps
1. Survey the exchanger: material, diameter, wall thickness, history. 2. Clean the tubes. 3. Calibrate with a reference tube containing artificial defects. 4. Scan 100% of the tubes with an electromagnetic technique. 5. Confirm with IRIS on a sample and on flagged tubes. 6. Report with tubesheet map and plugging recommendations.
What to look for in the equipment
Supported techniques (ECT, RFT, NFT, MFL), number of channels and frequencies, acquisition speed, analysis software with tubesheet mapping, portability and probe availability for the tube diameters in your plant.
Reference standards
ISO 15549 (eddy current — general principles), ASTM E690 (eddy current testing of non-magnetic heat exchanger tubes), ASTM E2096/E2096M (remote field testing of ferromagnetic tubes) and ASME BPVC Section V, Article 8. Compliance depends on the complete procedure, calibration, qualified personnel and applicable acceptance criteria.
Frequently asked questions
How often should heat exchanger tubes be inspected?
It depends on service, history and the owner's integrity programme; many plants inspect at every planned shutdown, prioritising critical exchangers.
Can one instrument cover ECT and RFT?
Yes. Multi-technique instruments such as the EEC-309 support ECT and RFT with the appropriate probes, covering both ferromagnetic and non-ferromagnetic tubes.
Is IRIS still needed?
Yes, when a quantitative remaining-wall measurement is required. Electromagnetic assessment is not equivalent to ultrasonic IRIS measurement.
Equipment and technical support
Synvor supplies non-destructive testing equipment and provides technical support in selecting the right method and configuration for your application. The inspection itself is performed by the asset owner or a qualified inspection company.