Rigid metal conduit , is of heavy-wall construction to provide a maximum degree of physical protection to the conductors that run through it.
Rigid metal conduit is available in steel, aluminum, brass, and stainless steel. The conduit can be
threaded on the job with a standard pipe die, or nonthreaded fittings may be used where permitted.
NEC 300.6 covers the need for protection of metal raceways against corrosion. When rigid metal
conduit is threaded in the field (on the job), the thread must be coated with an approved electrically
conductive, corrosion-resistant compound if corrosion protection is necessary.
RMC bends of 45° and 90° can be purchased, or they can be made using special bending tools. Bends in trade sizes 1⁄2, 3⁄4, and 1 RMC can be made using hand benders or hickeys, See above the Ideal Bending Guide in Appendix I of this text for additional information on using a hand bender. Hydraulic benders must be used to make bends in larger sizes of conduit.