Eddy Current Testing

Eddy Current Testing

For a business, it’s a critical part of preventative maintenance designed to protect and maintain your capital equipment.

Eddy current testing is one element of the preventative maintenance necessary to keep your costly chiller operating smoothly.

Eddy current testing (ECT) offers a peek into the future, predicting when the danger of heat exchanger tube failure is imminent. ECT identifies pits, general corrosion or wear on the heat exchanger tubes, giving operators ample warning to take action before failure interrupts operations.

Follow Manufacturers Recommendations for ECT Schedule

Your mechanical contract service provider (Trane, York, Carrier or others) can provide recommendations for a schedule of ECT on condenser and evaporator tubes. Typically, tubes should be eddy current tested every three years on condenser tubes.

Why Tubes Fail

Tubes can fail for a number of reasons.

Corrosion or pitting may accumulate on the fluid side. Erosion or abrasion may occur on the tube support side. Supports/ stays can vibrate on the outside of a chiller tube, causing it to fail mid-season. Failure can have serious effects on cooling capacity, so early detection is vital. ECT is a valuable tool for detecting issues before they’re obvious.

Eddy Current Testing Explained

What is eddy current inspection?

ECT is one of many electromagnetic testing methods in the category of nondestructive testing (NDT), all of which make use of electromagnetic induction to both detect and characterize surface and sub-surface flaws in conductive materials.

In the cooling plant, ECT uses electromagnetic induction to reveal defects in tubing. A probe is inserted into the tube and pushed through the entire length of the every single tube. It is a tedious job. Defects cause a change in eddy current, along with a corresponding change in phase and amplitude. These changes are detected by measuring the impedance changes in the coil, and records are maintained

ECT is primarily used for surface inspection and tubing inspections. Surface inspection applications are primarily in the aerospace industry, as well as in the petrochemical industry, since ECT can detect tight cracks.

Tubing inspection is limited to non-ferromagnetic tubing for the most part. It’s highly sensitive for detecting and sizing pits. ECT detects wall loss and corrosion, but is less accurate in sizing the defects in these arenas.

Advantages of Eddy Current Inspection

ECT is highly valued in the cooling industry for a variety of reasons. Inspection offers immediate results without waiting for lab analysis; ECT test equipment is highly portable; the test probe does not need to contact the part; and complex shapes and sizes of conductive materials are easily analyzed.

Chemtex can help you by directing to companies who perform ECT testing. As always, please give us a call if you’d like to know more about how ECT can keep your chiller working both efficiently and reliably.