This document defines the requirements for how mechanical compliant items in a final element can be evaluated according to the principles of EN 61508 to integrate them into a safety-related system. It provides a method to determine all relevant factors, associated with the product, and thereby meet the specific needs of users of the product. The basic prerequisite for the application of this document is that the intended use is known. This document describes a system to minimize systematic faults to achieve the targeted Safety Integrity Level (SIL). This document is applied to single compliant items (e.g. valve, actuator or mechanical portions of solenoid valves) or to assemblies of several of these compliant items and interconnecting compliant items and components (e.g. gears, adaptors, brackets, etc.). Electrical, electronic or programmable electronic components are assessed according to EN 61508. This document does not apply to: — manually operated valves; — items in safety systems or risk-reducing devices that are not assessed and operated according to the principles of functional safety (e.g. automatic safety valves like pressure relief valves). The methods described can also be used for other mechanical compliant items in a final element of the safety-related system if the applicability is confirmed by appropriate expert knowledge (e.g. dampers, brakes, clutches).