46 CFR §58.30-30

1. (a)The requirements of this section are applicable to those hydraulic and pneumatic systems listed in § 58.30-1 and to all pneumatic power transmission systems.
2. (b)Fluid power cylinders consisting of a container and a movable piston rod extending through the containment vessel, not storing energy but converting a pressure to work, are not considered to be pressure vessels and need not be constructed under the provisions of part 54 of this subchapter.
3. (c)Cylinders must be designed for a bursting pressure of not less than 4 times the maximum allowable working pressure. Drawings and calculations or a certified burst test report must be submitted to show compliance with this requirement.
4. (d)Piston rods, except steering gear rams, must be either of corrosion resistant material or of steel protected by a plating system acceptable to the Commandant.
5. (e)Materials selection must be in accordance with the requirements of § 58.30-15(b).