Chiller Eddy Current Testing

Eddy Current Testing (ECT) is a valuable tool for preventative maintenance in any chiller. By detecting corrosion, cracking and other stress points long before they could be detected by visual inspection, ECT enables operators to identify and resolve problems early. Weakened points and potential failures, if left untreated, could cause bigger problems in the future.

ECT uses electromagnetic induction to detect, identify, and locate surface and sub-surface flaws. It administers an electromagnetic field, and analyses the way in which it is disrupted, revealing flaws. Testing can identify problems on both the inside and the outside of a tube. ECT is a nondestructive testing method (NDT); it allows operators to evaluate the condition of their systems in a non-invasive way.

The testing delivers valuable data such as internal and external defects; percentage of metal loss at each defect; and location of each defect.

When to Perform ECT

ECT should be performed on a regular schedule:

• Test condenser tested every three years
• Test evaporators tested every five years

If the water treatment program uses pH control with an acid-based product, the condenser should be tested every year.

It’s also critical to test the condenser tubes immediately after an acid cleaning. Acid cleaning before the suggested retest due date listed in the report will void the most recent eddy current results.

By identifying, locating and addressing issues of corrosion or stress as early as possible, ECT can reduce the potential for equipment failure and costly downtime. Most defects are difficult to read in tube support and tube sheet areas, so relying on this extremely useful testing tool means you can check these areas conclusively.

It’s important to note that Eddy Current Testing is not a leak detector. While it does detect corrosion, it is not a good strategy for detecting holes. Pressurizing and/or vacuum testing the vessel in question are recommended methods to detect holes.

Your ECT Procedure

In summary, we suggest you do the following:

• Review the last time ECT was performed on your chiller
• Follow up on any non-rejectable defects that were identified on your previous eddy current analysis
• Schedule a test of both the condenser and evaporator

Prevention is the best cure. Make sure you establish and follow a routine of ECT to stay on top of your chiller’s condition. ECT will deliver early indications of problems, allowing you to treat them before they get out of hand. As always, feel free to contact Chemtex with your questions about ECT and other types of NDT.