|Advantages of Eddy Current Testing|
|Advantages of Eddy Current Testing:
Determine general tube integrity
Detect tube OD problems
Detect water treatment problems
Detect water flow problems
Detect machine vibration problems
Detect tube manufacturing problems
Detect and prevent potential tube failure problems
Compare future inspections to monitor tube integrity
There are many different problems that may occur in any particular chiller, depending on design, location, off season storage, maintenance, operation, etc. Eddy Current Testing is the only reliable, affordable and quick method of inspection that can detect most chiller tube problems before a tube rupture occurs. Understanding that nothing is 100% accurate, there are some limitations to Eddy Current Testing being a comparative method of inspection. There are many variables that occur in the many different types of chiller tubing that may affect the true accuracy of Eddy Current Testing. Still, the advantages greatly outweigh the disadvantages with top of the line equipment, probes, and experience that ALTEC Inc. has to offer. Any potential tube failure detected by Eddy Current Testing can save thousands of dollars and prevent lengthy shut down time, during peak chiller season.
|Advantages To A Baseline Eddy Current Inspection|
With today’s environmental issues and the demand for energy efficiency has forced tube manufactures to engineer chiller tubes for the best performance possible. To achieve this efficiency, a fin or enhancement is mechanically knurled into the ID and OD of a .028” thick wall tube.
There are different processes that a tube undergoes to achieve this. The internal ID fin is spirally knurled to increase water turbulence, thus increasing the heat transfer rate, while on the outside of the tube a fine spiral fin is knurled to increase surface area for more efficient Freon boiling and condensing.
Periodically this process can cause either, ID, OD or a combination of both, tube wall damage. Another tube manufacturing defect is Zipper Cracking. This type of defect is from a lap, seam or a void in the initial tube material that gets drawn out as the tube gets the lengthened. The signal generated from this type of defect is very small due to a resistive change only (no volumetric wall loss) and can be very deep (ID or OD). This type of defect may propagate during chiller operation. Any indications found in chiller tubes when the chiller is new can be monitored to ensure tube integrity.
The following questions come into play when a chiller is inspected and defects are found after being in operation for a number of years.
- Is this indication from tube manufacturing or chiller operation?
- If the indication is from tube manufacturing, was it this depth from the beginning or did it propagate deeper?
- If the indication propagated, how long did it take to become this depth?
- Has the water chemical treatment been administered properly?
- Is the chiller operation and water flow at manufacturing specs?
The advantages of performing a baseline eddy current inspection would eliminate all questions pertaining to tube integrity, chiller operation, and water chemical treatment problems.