Magnetic NDT Techniques have wide applications. ALS can assist in using them to your advantage.
ALS boasts a broad range of NDT techniques based on the principal of magnetism. These techniques rely on the changes that physical features such as:
- Weld Defects
Create in a magnetic field induced in the tested component or structure. Using various different sensing techniques, these changes in the magnetic field are revealed and our expert technical staff interpret the size and nature of the defect present.
ALS experienced staff provide:
Magnetic Particle Testing – Magnetic Particle testing is the process of examining for features such as cracks, weld defects etc using magnetic particles which are drawn to the surface defects by a magnetic field. Magnets are commonly handheld, however ALS maintains large magnetic beds to allow high production magnetic particle testing when required.
Applications – Surface breaking defects across all magnetic components
Advantages – A relatively low cost, low preparation fast technique for inspecting surfaces of magnetic components.
Eddy Current Techniques
By using electromagnetic induction to create currents in an inspected component, defects are detected by the interruption they cause to these currents. This science has created many fantastic applications for which ALS has significant expertise, including:
Manual Eddy Current – Using handheld probes, surface defects can be detected through many surface coatings, removing the need to remove surface coatings such as paint, potentially creating significant savings.
With some of ALS more advanced testing equipment, probes are part of encoded arrays, improving productivity.
Advantages – Detect surface and slightly sub-surface defects in magnetic surfaces without removing non-magnetic surface coatings (i.e. paint). Detection of sub-surface defects in non-magnetic materials may also be possible.
Applications – Painted structures, vessels and tanks, more common applications including cranes, road tankers.
Saturated Low Frequency Eddy Current – SLOFEC – The SLOFEC technique is a world leading technology for fast and accurate corrosion screening and has exceptional capabilities to deliver unmatched high quality defect reports.The main applications of this technique are the inspection of storage tank floor plates, pipelines and plant piping and pressure vessels.
Advantages – Ability to rapidly screen large surface areas of magnetic materials and can detect very small and isolated corrosion.
Applications – Large magnetic surfaces, including Tanks, Pipelines and Pressure Vessels.
Magnetic Biased and Remote Field Eddy Current – These techniques are designed for finding loss of wall thickness and flaws in magnetic tubes such as heat exchangers and boiler tubes.
Advantages – Ability to rapidly and accurately scan magnetic tubing.
Applications – Ferrous Tubing, including Heat Exchangers and Boiler Tubes
Pulsed Eddy Current (PEC) – PEC provides rapid screening of insulated (lagged) components for the detection of Corrosion Under Insulation (CUI).
Advantages – Components can be scanned while still in operation, large areas can be covered as part of a structured integrity management strategy.
Applications – Scanning of piping, vessels, as well as fireproofing on vessels, gas sphere legs, structural steel.
Magnetic Flux Leakage (MFL)
Magnetic Flux Leakage techniques apply the principal of saturating a magnetic material and recording leakage of the magnetic field associated with areas of metal loss, corrosion and cracking. The technique is excellently applied to large areas where corrosion is likely to have occurred. Specialist equipment jigs are also owned by ALS that allow scanning of wire ropes, where corroded and broken internal metal strands of wire ropes can be assessed. MFL, can also be applied for inspection of ferromagnetic tube materials.
Advantages – Ability to rapidly scan large areas of magnetic material for wall loss and corrosion.
Applications – Pipe Scanning, Heat Exchanger Tubing, Tank Floor Scanning, Wire Rope Scanning.
RFT - Bracelet Corrosion Detection
RFT - Bracelet Corrosion Detection Introduces a remote field eddy current signal into the ferromagnetic material and can penetrate insulation or lagged components, as well as fireproofing.
Advantages - Can scan many meters by rolling the bracelet probe along the outer surface of insulated piping, fireproofing (within thickness limits), and vessels shells.
- Scanning of insulated piping and vessels for the detection of corrosion under insulation (CUI). Detection of corrosion of the piping/vessel walls on both internal and external surfaces.