What is Eddy-Current?
Eddy-Current is the fastest and most accurate NDT method for assessing the condition of the installed tubes in your chiller vessel. Eddy-Current is NOT a leak test. In the hands of a qualified analyst, this method of testing can provide information vital to maintaining the functionality of your expensive HVAC equipment. In most cases, defects of sufficient severity to leak will be identified during the test so that appropriate steps can be taken to prevent further damage. Some defects are too small to be detected or might be masked by erroneous signals caused by metallurgical or mechanical variances.
What types of damage can be detected?
Eddy-Current testing can detect damage due to Erosion, Corrosion, Mechanical Damage, Chemical Damage, Electrolysis, or any combination of these issues. Eddy-Current can "see" the inside diameter as well as the outside diameter tube wall and can detect damage to both I.D. and O.D. tube walls.
How does Eddy-Current work?
At the risk of oversimplifying: Eddy-Current is also known as Magnetic Field Testing. An inspection probe is inserted into each tube. This probe generates a 360 degree magnetic field in the tube wall. As the probe moves through the tube, defects create a disturbance in the magnetic field(eddy-currents). This disturbance causes a change in resistance in the field coils which is displayed on the test instrument scope as a signal. The type and severity of the defect is determined through phase analysis as well as the degree of signal deflection on the test instrument scope.
When should Eddy-Current be performed?
The best time to perform an Eddy-Current test is during the annual inspection. The frequency of this test is based on the type and severity of the damage detected. A machine with minimal or no damage can be tested every 2 to 3 years for the condenser and 3 to 5 years for the evaporator. As the severity of the damage increases, the test frequency should also increase. Damaged tubes can be quickly and easily plugged to minimize machine downtime and to prevent further damage.
Why should this test be performed?
A properly performed Eddy-Current Test can identify issues or monitor ongoing damage such as erosion or corrosion. When performed at regular intervals, this tool can assist the Plant Engineer in making decisions concerning periodic maintenance such as water treatment to correct the issue. For more serious damage, it can be used to predict when to retube or replace the vessel.
Who should perform the test?
A properly trained Analyst will strive to provide comprehensive information concerning the status of the tubes being tested. TECCIS analysts report all issues found during the test. TECCIS analysts adhere to industry standards concerning condemning tubes based on defect severity. TECCIS analysts periodically condemn tubes that other analysts will not due to our extensive knowledge and experience related to chilled water tubes. Chillers are our specialty. We do not perform eddy-current on Boilers or aircraft rivets, just chillers. Teccis analysts utilize probes specific to the typical materials found in chillers. Our suggestions are based on the information from the test combined with our knowledge and expertise.