Eddy Current Tube Inspection:
Eddy currents are alternating electrical currents induced into a conductive material by an alternating magnetic field .The eddy current tube inspection described are designed to detect and classify eddy-current responses originating from metal loss in non-ferrous tubing, by the measurement of amplitude and phase of eddy current responses to flaws and comparing them to manufactured defects in standard reference tubes.
Should the passage of the induced currents within the material be modified in any way then the effects of the change in value in the induced currents can be analyzed and presented so that the NDT inspector may interpret the possible cause of their modification.
Reference tubes of the same dimensions, material and geometry as the tube type to be inspected shall be machined with artificial defects as stated in ASME 5 Article 8 Appendix II, II – 860.2 with additional defects added or additional reference tubes used to formulate the required depth curves “See Appendix B”. Each reference tube must be permanently identified by a unique serial number. Orientation of the exchanger/tubes in terms of inspection end, row & unambiguous tube numbering system together with the extent of the survey, recording level and location of the tubes to be inspected will be established via a pre-inspection consultation with the Client (Instructions shall be detailed in the contract document or work request sheet).
Applications of Eddy Current tube Inspection:
Tube Inspection of Heat Exchanger
Tube Inspection of Chiller
Condenser Tube Inspection
Heat Exchanger Tube Inspection by Eddy Current Inspection method:
Various sizes and different of tubes are used in Heat Exchangers of petrochemical or power generation industries. For remaining life assessment and corrosion mapping of tubes; Eddy Current tube inspection method is widely used in industries. Internal diameter of tubes can be measured by high speed eddy current inspection techniques by different non ferrous probes and in order to identify the thinning/corrosion survey of tubes. Eddy Current Tube inspection can consider as a preventive maintenance techniques allowing operators to decide replacement of heat exchanger tubes, tube pugging or complete replacement of heat exchanger to meet the safety requirements and to ensure the safe environment at power generation industry/Petro chemical plant.
Depending upon the tube material and wall thickness, operating frequency may varies of few KHz for thick copper tubes and for thin walled titanium it may 600 KHz.
Power Plant Condenser Tube Inspection by Eddy Current Inspection method:
EIWAA offer eddy current tube inspection for power plants to avoid unwanted condenser tube leakage and the avoidance of force shutdown. Eddy Current tube inspection is widely used to detect typical tubing associated defects such as pitting, corrosion, longitudinal and circumferential cracking, fretting, wall thickness and erosion.
Eddy Current Chiller Tube Inspection by Eddy Current Inspection method
Eddy Current inspection is the best method of chiller tube inspection by combing the features of simultaneous injections and multiplexed frequencies in an eddy current instrument to detect abnormal defects. Chiller tube defects which are identified by chiller tube eddy current inspection methods are Pitting, Freeze Ruptures, External corrosion and internal pitting.