EDDY CURRENT TESTING
Eddy-current testing (also commonly seen as eddy current testing and ECT) is one of many electromagnetic testing methods used in nondestructive testing (NDT) making use of electromagnetic induction to detect and characterize surface and sub-surface flaws in conductive materials.
Applications
ECT finds applications in both tubing and surface applications
Detection capabilities to defect type in tubing
Several types of defects can be detected in tubing with varying degrees of success:
- Inner-diameter (ID) pitting: excellent
- Outer-diameter (OD) pitting: excellent
- Axial cracking: acceptable, but limited
- Circumferential cracking: acceptable, but limited
- ID corrosion: excellent
- OD corrosion: excellent
- Defects at tubesheet: acceptable, but limited
Sizing capabilities to defect type in tubing
Several types of defects can be sized in tubing with varying degrees of success:
- Inner-diameter (ID) pitting: good
- Outer-diameter (OD) pitting: excellent
- Axial cracking: good
- Circumferential cracking: unsuitable
- ID corrosion: good
- OD corrosion: excellent
- Defects at tubesheet: good
Suitability according to material
ECT is limited to being used on non-ferromagnetic materials.
ECT on surfaces
When it comes to surface applications, the performance of any given inspection technique depends greatly on the specific conditions — mostly the types of materials and defects, but also surface conditions, etc. However, in most situations, the following are true:
- Effective on coatings/paint: yes
- Computerized record keeping: partial
- 3D/Advanced imaging: none
- User dependence: high
- Speed: low
- Post-inspection analysis: none
- Requires chemicals/consumables: no