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Best Eddy Current Testing (ET) Companies

Eddy current testing (ET) is a versatile electromagnetic inspection method that excels in two distinct applications: high-speed heat exchanger and condenser tube inspection, and high-sensitivity surface and near-surface crack detection on conductive components. In the process industries, ET is the primary method for evaluating tube wall loss, corrosion pitting, and stress corrosion cracking in heat exchanger bundles — thousands of tubes can be inspected per day with automated rotating probe systems. In aerospace, ET (and its variant, eddy current array — ECA) is used to detect fatigue cracks in aircraft structures, fastener holes, and turbine components. Companies offering ET services range from specialized heat exchanger service providers to aerospace NDT labs with multichannel ECA capability.

Why these suppliers?

  • ✓ET is the fastest method for heat exchanger tube inspection — automated multi-frequency ET systems can evaluate thousands of tubes per shift, making ET essential for refinery and power plant turnaround schedules.
  • ✓Eddy current array (ECA) provides high-resolution imaging of surface and near-surface cracks in complex geometries — particularly valuable for aerospace structural inspections where probe contact and scan coverage must be optimized.
  • ✓Multi-frequency ET analysis can distinguish and characterize different defect types (wall loss vs. pitting vs. baffle cuts) in heat exchanger tubes, providing actionable fitness-for-service data rather than just pass/fail results.

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Frequently Asked Questions

When is eddy current testing used for heat exchanger inspection?
ET is the standard inspection method for non-ferromagnetic heat exchanger tubes (copper, copper-nickel, brass, austenitic stainless steel, titanium, aluminum). For ferromagnetic tubes (carbon steel, ferritic stainless steel), Remote Field Testing (RFT), Magnetic Flux Leakage (MFL), or Near Field Testing (NFT) are used instead. ET tube inspection can detect internal and external wall loss, pitting, erosion, stress corrosion cracking, and intergranular attack. Results are reported as percent wall loss, guiding plugging decisions and remaining life assessments.
What is eddy current array (ECA) and how does it differ from conventional ET?
Conventional ET uses a single coil or differential pair and requires the probe to be mechanically scanned over the inspection surface. ECA uses a multi-coil array that can cover a wider area in a single scan pass while producing a C-scan image of the inspection zone. ECA dramatically reduces scan time and improves probability of detection for small cracks, particularly in complex geometries like turbine blade roots, fastener holes, and weld toes. ECA is increasingly replacing conventional ET for high-value aerospace structural inspections where imaging and permanent records are required.
What certifications are needed for ET inspection?
ASNT Level II ET certification is required for independent inspection and data interpretation under SNT-TC-1A. For heat exchanger tube inspection, additional qualification on tube bundles of similar construction (material, OD, wall thickness) is typically required, as ET data interpretation is highly configuration-specific. For aerospace applications under NAS 410, Level II with NAS-specific training is required. Companies performing ET should be able to provide calibration standards documentation and demonstrate procedure qualification on representative specimens.