Tube inspections has always been a crucial part of Industrial inspections especially in the Oil & Gas, Petrochemical, Power generation and HVAC industry. Shell and tube heat exchangers do not contain moving parts and require little maintenance. But tubes play a vital role in equipment operation and are subjected to inner and outer-diameter pitting and corrosion, circumferential and longitudinal cracks, metal loss, erosion and fretting.
Thus a thorough inspection of tubes is advisable on regular intervals. In many cases a heat exchanger failure or malfunction could cause a complete shutdown of operations.
Challenges with standard Eddy Current Inspection:
- Circumferential cracking, especially at the tube-sheet , is very difficult to detect and characterize
- Defect positioning & sizing of defect
So how to gain optimum and more accurate tube inspection data?
Eddy Current Array is the solution!
Eddy Current Array (ECA) Technology:
- An eddy current array (ECA), is an extension of standard Eddy Current where a series of coils are arranged in a row. However, this could lead to suboptimal results. That’s why ECA probes use multiplexing.
- Multiplexing involves activating and deactivating coils in specific sequences to leverage the probe’s width. Multiplexing also minimizes the interference between coils in close proximity (mutual inductance) and maximizes the resolution of the probe.
Advantages of using Eddy Current Array:
- A larger area can be scanned in a single-probe pass, while maintaining a high resolution
- More sensitive to circumferential cracking
- Less operator dependent – eddy current array probes yield more consistent results
- Better defect detection capabilities
- Easier analysis because of simpler scan patterns
Standards guiding PEC Inspection :
ASME Section V, Article 8 | ASTM E 690
