The Western Instruments WD-Series Magnetizing / Demagnetization MPI Coils is designed specifically for Magnetic Particle Inspection, and have grown in popularity from the Oil Country Tubular Goods Inspection Industry. Drill Pipe, Couplings and other Drilling Tools are regularly inspected for Transverse Cracks, which are normally found in the last engaged thread. These inspections are often performed in the Field, but are just as common in manufacturing and repair facilities.