BS EN 17955:2024
$215.11
Industrial valves. Functional safety of safety-related automated valves
| Published By | Publication Date | Number of Pages |
| BSI | 2024 | 72 |
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).
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | undefined |
| 8 | 1 Scope 2 Normative references |
| 9 | 3 Terms, definitions and abbreviations |
| 14 | 4 Relationship and conformity with EN 615081, −2, −4, −6 and −7 |
| 16 | 5 Basic requirements for development and production 5.1 Evaluation of systematic capability 5.2 Documentation management 5.3 Functional safety management 5.4 Safety lifecycle requirements for development and production of safety-related automated industrial valves 5.4.1 Objectives and requirements 5.4.1.1 General |
| 17 | 5.4.1.2 Objectives 5.4.1.3 Requirements |
| 21 | 5.4.2 Mechanical requirements specification 5.4.2.1 Objective 5.4.2.2 General requirements 5.4.2.3 Requirements |
| 22 | 5.4.3 Mechanical validation planning 5.4.3.1 Objective 5.4.3.2 Requirements |
| 23 | 5.4.4 Mechanical design and development 5.4.4.1 Objective 5.4.4.2 General requirements |
| 24 | 5.4.4.3 Requirements for proof tests and diagnostic tests 5.4.4.4 Requirements for the avoidance of systematic faults 5.4.4.5 Requirements for the control of systematic faults |
| 25 | 5.4.4.6 Requirements for implementation of final elements 5.4.5 Mechanical system integration 5.4.5.1 Objective 5.4.5.2 Requirements |
| 26 | 5.4.6 Mechanical system installation, commissioning, operation and maintenance procedures 5.4.6.1 Objective |
| 27 | 5.4.6.2 Requirements |
| 28 | 5.4.7 Mechanical system safety validation 5.4.7.1 Objective 5.4.7.2 Requirements 5.4.8 Production 5.4.8.1 Objective |
| 29 | 5.4.8.2 Requirements 5.4.9 Modification of compliant items 5.4.9.1 Objective |
| 30 | 5.4.9.2 Requirements 5.5 Verification 5.5.1 Objective 5.5.2 Requirements |
| 32 | 5.6 Functional safety assessment 5.6.1 Objective 5.6.2 Requirements 6 Classification of the compliant item 6.1 Demand mode and utilization rate |
| 35 | 6.2 Type of final element/compliant item 7 Field failure data 7.1 Field failure data analysis procedure |
| 36 | 7.2 Use of field failure data for pre-existing compliant items 8 Qualification testing 8.1 General 8.2 Test planning/test conditions |
| 37 | 8.3 Pre-conditioning of test samples 8.4 Cycle testing and B10D values 8.5 Environmental testing 9 Determination of failure rates |
| 38 | 10 Operational testing, maintenance and time restrictions 10.1 Online diagnostic tests 10.2 Proof test 10.3 Proof test coverage (PTC) |
| 39 | 10.4 Maintenance 10.5 Useful lifetime 10.6 Storage time 11 Safety manual in addition to an installation, operation, and maintenance manual |
| 41 | Annex A (normative)Techniques and measures to avoid and control systematic failures |
| 48 | Annex B (normative)List of failure rates for common compliant items |
| 51 | Annex C (normative)FME(D)A to identify and evaluate the effects of different failure modes C.1 FME(D)A C.2 Input information to carry out an FME(D)A C.3 FME(D)A procedure |
| 54 | C.4 FMEDA example |
| 56 | C.5 List of functional units and their failure rates with a low utilization rate (LUR) |
| 58 | C.6 List of functional units and their failure rates with a high utilization rate (HUR) |
| 60 | Annex D (informative)Safety manual |
| 62 | Annex E (informative)Examples for the evaluation of the mechanical design E.1 General E.2 Examples E.2.1 Bolting connections E.2.1.1 General requirements |
| 63 | E.2.1.2 Fixation against self-loosening E.2.2 Force-locked connections E.2.2.1 General requirements E.2.2.2 Requirements for safety against loss of function S > 4 E.2.2.3 Requirements for safety against loss of function S > 10 |
| 64 | E.2.3 Form-locked connections (structural component strength) E.2.3.1 General E.2.3.2 Static loads E.2.3.3 fatigue loading E.2.4 Springs E.2.5 Bearings E.2.5.1 Roller bearings E.2.5.2 Friction bearings |
| 65 | E.2.6 Gears and force transmission linkages |
| 66 | Annex F (informative)Estimation of random failure rates with Bayesian integration between “basic” failure rates and field feedback F.1 General F.2 Procedure |
| 67 | F.3 Formula F.3.1 General |
| 68 | F.3.2 Estimation of the verisimilitude factor V |
