API Std 6DX Second Edition PDF
This standard defines the requirements for design, mechanical integrity, and sizing of actuators and related components, and is applicable to all types of electric, pneumatic, and hydraulic actuators, inclusive of mounting kit, installed on valves that conform to API Specification 6D.
This standard applies to actuators that are part-turn, multi-turn, or linear in action. It applies to part-turn actuators capable of withstanding torsional forces, multi-turn actuators capable of withstanding torsional forces and axial thrust, and linear actuators capable of withstanding axial thrust.
This document is not applicable to actuators installed on control valves, valves being used for regulation, valves in subsea service, handheld powered devices, stand-alone manually operated gearboxes, instrument tubing and associated fittings, and actuator control equipment.