Introduced in the 1950’s, eddy current tube analysis has become the dominant nondestructive test (NDT) used nationally to inspect nonferrous shell & tube heat exchangers used throughout the military, nuclear, heavy equipment, comfort cooling, cogeneration/power, pulp/paper mill, process, & HVAC chiller industries.

Eddy Current Inspection offers:
  • Quantitative/Qualitative surface/subsurface analysis of defects on both (I.D & O.D) orientations (some examples above);
  • Identifies alloy composition, hardness, specification, wall thickness, geometrical changes, and can help indicate tube cleanliness;
  • Easily overcomes in-service conditions typical to chillers;
  • Accurate, reliable, reproducible results due to the calibrated & certified test procedures;
  • Portable, efficient, & cost effective

These attributes have driven its value & popularity, that, as a result, it is consistently used as a part of predictive/preventative maintenance (P/PM), warranties, service agreements, annuals, conversions/retrofits, insurance protocols, quality control, due diligence, litigation, commissioning, & even, water treatment programs.

Eddy current analysis has been endorsed and actively utilized by A/C chiller manufacturers (Carrier, D/B, McQuay, Trane, JCI/York, etc…), controls groups (Honeywell, Siemens, Yamas, etc…), independent service companies, mechanical contractors, engineering firms, property management groups, & insurance providers worldwide.

The science of eddy current tube testing is known as electromagnetic inductance. The test instrument controls the frequency (F) fed into the eddy current probe. As the probe passes through the tube, eddy current flow is induced on both I.D/O.D surfaces/subsurfaces. Any change in tube wall thickness and/or metallurgical microstructure disrupt the steady electromagnetic eddy current flow, causing an impedance change that results in instantaneous impulses (flying dot/lissajous signals) on the instrument monitor.

Phase manipulation & amplitude (gain) are used to process the impulses. Along with F, these test parameters are controlled by the field technician/analyst. This demands that the on-site individual possess the necessary expertise to properly calibrate & actively interpret the signals as they are manifested on the screen.

Personnel who are engaged in testing are certified to Level I (trainee), Level II (technician), or Level III (analyst), depending on their individual companies definition standards, and based on the individual’s knowledge, education, background, training, & experience.

The American Society for Nondestructive Testing (ASNT) utilizes the governing document SNT-TC-1A Recommended Practice, allowing firms providing NDT services to define, train, educate, & certify their personnel to Level I, II, or III standards. As such, certification records of test personnel are always available to the client to verify credibility, reputation, longevity, & expertise.