Non-destructive testing employs a wide range of techniques and methods to fully analyse and understand the various pieces of equipment being tested. To this end a wide range of equipment has also been developed, some proprietary, to meet the needs of the industry and continue the improvement and thoroughness of inspection and evaluation. In this article we aim to cover several different types of technology that use the LFET technique, their applications, and their advantages. Let's take a look. LFET - Low Frequency Electromagnetic Technique as it's known was developed to inspect flat bottomed storage tank floors originally. As the technique has matured it's been improved to inspection convex or concave piping and tubing surfaces as well, and several different pieces of technology have been developed to this end. It's main applications include: Boiler Waterwalls, Reheaters/Superheaters, Storage Tanks, Pipelines, Fire protection piping, coal mill piping, general piping, pressure vessels and heat exchanger shells. Waterwall inspection - The TS-2000 is used for the inspection of waterwalls, it's capable of inspecting thick ferrous material up to.500" (12.7mm). No couplant is required and comes in a variety of contoured scanners to inspect any tube diameter. The TS-2000 is capable of performing hot-side surface scans, and can inspect non-ferrous as well as ferrous materials. Common problems detected include; corrosion cells, hydrogen damage, caustic gouging, pitting and general wall loss. Tank floor Inspection - For tank floors, the Falcon Mark II can be used, it features 32 channels and a 13" display, flaw threshold LEDs, over speed alarm, high resolution display and real time processing and display. Tank floor inspection required minimal floor preparation, which makes it easy to get started with. Ferrous and non-ferrous materials can be inspected and inspection can be performed through coatings. Common flaws include pitting and wall loss. O.D Pipeline Inspection - OD (Outer diameter) Pipeline inspection, uses a high speed scanner called a LineCat. The LineCat can be adapted to fit different pipes and environments, including a mechanically driven option as well as having the capability to operate in sub-arctic temperatures. As with tank floor inspection, pipeline inspection can be performed on ferrous and non-ferrous materials, and scan through coatings, uniform scale and rust. One nice feature of the LineCat, is due to it's shape, it gives a 360 degree view of the pipe, though for larger pipes (>10" OD - 254mm) multiple scans will be required. Speeds of up to 10-15ft / minute can be achieved. For more general pipeline inspection the PS-2000 can be used, it's a lightweight scanner, using frequencies from 5Hz to 30KHz, can be used manually or mounted on a crawler. The scanner is capable of distinguishing between Internal Diameter (ID) and OD defects. Testing can be performed "on-line" whilst the pipe is in use, with the product inside having no bearing. It can be used on straight and bending sections and detects flaws such as MIC attack, FAC, erosion, corrosion, pitting and cracking. As you can see LFET has a wide variety of uses, technologies and different applications making it a versatile technology, with a great future in the non-destructive testing
