Abstract: A elbow joint for a permanently mounted explosion-proof pipe which is useful for housing and commercial plant sealed electrical wiring systems that includes a plurality of movable rollers mounted within the inside gradually curved wall portions of the elbow pipe which allows an electrical conductor to be inserted or withdrawn around corners in the piping system quickly and easily. The elbow may be molded or fabricated to include one or more undulations disposed on the inside curved surfaces (along the inside radius of the elbow) to house the rollers and axles therein. Because all interior surfaces and members are permanently sealed from possible explosively hazardous atmosphere, no explosive gases may enter the sealed electrical wiring system through this elbow joint, nor may possible internal electrical arcing escape from the elbow joint into a possibly explosive atmosphere.