This recommended practice encompasses design, analysis, fabrication, and installation of pressurized plain metal tubing used in fluid power systems to provide relative motion. Specific data given are for MIL-T-6845 tubing ranging from 1 4 " to 1" dia. used in 3000 psi hydraulic or pneumatic systems, Types I, II, III or IV applied to any type of vehicle. The flexible configurations of plain metal tubing are intended for application to actuators that oscillate about a pivot, to areas of large structural deflection such as reservoirs installation, and to areas of extreme environment where flexible hose could not survive.