Eddy Current Test uses electromagnetic induction to detect flaws in conductive materials. The eddy current test set-up consists of a circular coil placed on a test surface. The alternating current in the coil generates changing magnetic field, which interacts with the conductive surface and generates eddy current. The flow of eddy current can be disrupted due to change in resistivity or conductivity, magnetic permeability, any physical discontinuity. The change in eddy current flow and a corresponding change in phase and amplitude is measured against known values.

EDDY CURRENT SURFACE INSPECTION

• Eddy current test method can detect very small cracks in or near the surface of the material, the surfaces need minimum preparation
• It can deduct surface flaws on painted or coated surface.
• Need not required to remove protective surface coating.
• Some notable applications of Eddy current test are conductivity measurement, sorting of material, assessment of heat treatment conditions, sorting of materials based on hardness and strength, measurement of thin components.

EDDY CURRENT TUBE INSPECTION

• Eddy Current Tube Inspection is primarily for longitudinal crack detection pits, corrosion, erosion and axial cracking in nonferrous tubing.
• Use of multi frequency enables better analysis and flaw sizing.
• Probe needs a good fill factor to remain sensitive.
• It is very fast technique with 2 meter per second pulling speed.
• Able to discriminate the wall loss is on inner side and outer side.
• High sensitivity, good screening com sizing tool.

RFT INSPECTION FOR FERROMAGNETIC TUBES

• Remote Field Testing (RFT) successfully inspect ferromagnetic tubing such as carbon steel or ferrite, stainless steel. Offers good sensitivity in detecting and measuring defects resulting from erosion, corrosion, wear and baffle cuts.
• Detect inside and outside defects with approximately equal sensitivity.
• Probe needs a small fill factor to remain sensitive.
• It is less fast compared to eddy current inspection with 0.5 meter per second pulling speed.
• Can discriminate the wall loss is on inner side and outer side.

IRIS TUBE INSPECTION

• IRIS system works on the principle of Ultrasonic Testing. It is used as an alternate hypothesis for verify the results of Eddy current and RFT
• Detect inside and outside defects
• Probe needs proper centering device.
• It is quite slow technique but reliable.
• Able to discriminate the wall loss is on inner side and outer side.
• High probability of deduction and less prone for false call.

PULSED EDDY CURRENT FOR CORROSION UNDER INSULATION

• Pulse Eddy Current Testing (PECT) is a technique used for corrosion under insulation (CUI) screening on carbon steel structures as pipes, vessels, tanks and spherical tank legs without the need of contact with the steel surface.
• PECT is a static technique measure spot percentage variations in steel thickness through any nonmagnetic material between the sensor and steel surface such as air, insulation material, concrete, plastic coatings, paint, sea water, marine growth, deposits, oil etc.
• PECT is comparative technique, where the percentage variations measured on the specimen are compared with a calibration value which assumed to be the full wall thickness.