Abstract: Apparatus and method for protecting a producing oil well's sucker rod string from wear as the rod string reciprocates in the well's tubing string. Each rod guide has a network of passages encased within the body of the rod guide. As the sucker rods and rod guides move up and down through the tubing string, produced fluid is channeled through tunnels in the passages to exit ports from which the fluids are discharged at high velocity away from the guide. The fluid exits with suffficient force to push the rod string away from the tubing string at each exit port. In this way the streams of fluid tend to centralize the rod string near the center of the tubing string thereby averting contact between not only the rod string and the tubing string, but also between the guide itself and the tubing string. The discharged fluid also provides lubrication between the guide and tubing string in the event that contact between the components does occur.

Abstract: Air is flowed within an annulus fluidly connected to the load end of a pipe to be coated. A premeasured charge of powdered coating material is suspended in an injection airflow and then injected into the annulus. Spiral flow of the air and particles of coating material in the annulus is induced by successively jetting air into the annulus at selected angles to axial flow. The resulting powder cloud has spiral annular movement within the annulus toward the load end of the pipe. An optional conical deflector at the load end deflects the spiral cloud toward the wall of the pipe. The pipe is rotated counter to the tangential or circumferential component of the spiral flow. The nonaxial circumferential component of the spiral flow helps reduce the number of holidays, and insures that the coating material is deposited evenly through the length of the pipe for a uniform coating thickness. The powder cloud is much longer than the pipe. The excess coating material exiting the pipe discharge end is recycled.