Remote Field Testing of Ferromagnetic Tubes

Remote Field Testing (RFT) is the purely magnetic technique useful to detect flaws in materials with permeability sufficient to prevent significant penetration of eddy currents. RFT is primarily used to inspect ferromagnetic tubing since conventional eddy current techniques have difficulty inspecting the full thickness of the tube wall due to a strong skin effect in ferromagnetic materials. Eddy currents are also generated in tested material but particularly in the region near the excitation coils. However, the position of the receiver coils is far enough from the exciters that the influence of eddy currents is negligible. "Remote" magnetic fields are capable of passing through tested material. In penetrating the material, the magnetic field travels along the outside surface and the coils detect disturbances in the flux field in comparison to the primary magnetic field.

These can be very quickly scanned for both internal and external wall loss defects such as a corrosion, erosion, pitting, cracks, and wear scar.

RFT can be used to inspect any conducting tubular product. Evaluating the quality of products by Remote Field Testing method is the most effective for ferromagnetic materials like low carbon steels, chrome molly, duplex in units like:

• heat exchangers
• feedwater heater
• furnace tubes in vessels
• Texas Towers
• Went coolers with fin fan tubes

The 3D Push Pull High Speed Data Acquisition System consisting of professional Zetec's software allows for the checking of about 400 tubes per shift. Institute Gamma utilizes the highest technology of multi-frequency testing equipment including the Zetec's MIZ-27SI and RFT Amplifier.

Institute Gamma's qualified engineers and technicians perform maintenance and inspection services.

• Engineers with competence in maintenance analysis and planning, inspection planning, damage evaluation, material technology and risk based inspection.
• NDT senior inspectors on level 2 and 3 in accordance with EN-473/PCN-BIND certification system.
• NDT technician on level I and II with ZETEC certificates for RFT method
• Data analysts for eddy current on level IIA/QDA in accordance with EPRI S/G certification.
• Welding inspectors in accordance with European Welding Federation requirements and EN-719 standard.

Benefits of RFT tube testing are:

• Prevention of dangerous leaks
• Prevention of break down outages
• Accurate assessment of wall thickness loss up to 0,1mm
• Recorded measurement data , forecasting of wall loses, predictive maintenance
• Quantitative method
• Detecting abnormalities of used materials
• RFT doesn't need water and clean surface like the IRIS method
• RFT is more sensitive and sizes defects more accurately than other magnetic methods