Magnaflux MPI Test BarMagnaflux Magnetic Particle Test Bar The MPI Test Bar is a standardized test piece conforming to the requirements of NAVSEA T9074 AS GIB 010 271 to demonstrate magnetic particle equipment performance. The MPI Test Bar can be used with wet bench equipment, power packs, or magnetic yokes. The test bar includes both surface and sub surface flaws for use with AC, HWDC, and FWDC magnetizing currents. Surface notches in two directions on each side of the