The Safety Critical Systems Handbook

A Straightforward Guide to Functional Safety: IEC 61508 (2010 Edition), IEC 61511 (2015 Edition) and Related Guidance

David J. Smith, Kenneth G. L. Simpson

• Publisher: Butterworth-Heinemann
• Year: 2020
• ISBN:
  9780128202593
• Edition: 5
• Topic: Technology & Engineering
• Subtopic: Industrial Health & Safety
• Index: Technology & Engineering

The Safety Critical Systems Handbook: A Straightforward Guide to Functional Safety: IEC 61508 (2010 Edition), IEC 61511 (2015 Edition) and Related Guidance, Fifth Edition presents the latest guidance on safety-related systems that guard workers and the public against injury and death, also discussing environmental risks. This comprehensive resource has been fully revised, with additional material on risk assessment, cybersecurity, COMAH and HAZID, published guidance documents/standards, quantified risk assessment and new worked examples. The book provides a comprehensive guide to the revised IEC 61508 standard as well as the 2016 IEC 61511.

This book will have a wide readership, not only in the chemical and process industries, but in oil and gas, power generation, avionics, automotive, manufacturing and other sectors. It is aimed at most engineers, including those in project, control and instrumentation, design and maintenance disciplines.

• Provides the only comprehensive guide to IEC 61508 and 61511 (updated for 2016) that ensures engineers are compliant with the latest process safety systems design and operation standards
• Presents a real-world approach that helps users interpret the standard, with new case studies and best practice design examples using revised standards
• Covers applications of the standard to device design

Appendix 1

Functional Safety Management

Template Procedure

This procedure could be part of a company's Quality Management System (e.g., ISO 9001). It contains those additional practices (over and above ISO 9001) necessary to demonstrate Functional Safety Capability as would be audited by a reviewing body (see Chapter 7).

A large organization, with numerous activities and product types, might require more than one procedure, whereas a small company would probably find a single procedure satisfactory.

Again, the activities covered by a designer and manufacturer of instruments or systems will differ from those of a plant operator, which, in turn, will differ for a functional safety consultant/assessor.

This template has been successfully used by companies in the safety systems integration field and in consultancy firms. It consists of a top-level procedure and eight work practices to cover details of safety assessment (see Annex 1).

The terms used (e.g., Safety Authority, Safety Engineering Manager) are examples only, and will vary from organization; xxxs are used to designate references to in-house company procedures and documents.

This template should not be copied exactly as it reads but tailored to meet the company's way of operating.

Company Standard xxx Implementation of Functional Safety

Contents

• 1. Purpose of Document
• 2. Scope
• 3. Functional Safety Policy
• 4. Quality and Safety Plan
• 5. Competencies
• 6. Review of Requirement and Responsibilities
• • 6.1 Source of the requirement
  • 6.1 Contract or project review
  • 6.1 Assigning responsibilities
• 7. Functional Safety Specification
• 8. Life-Cycle Activities
• • 8.1 Integrity Targeting
  • 8.2 Random Hardware Failures
  • 8.3 ALARP
  • 8.4 Architectures
  • 8.5 Life-cycle activities
  • 8.6 Functional Safety Capability
• 9. Implementation
• 10. Validation
• • Work Instruction xxx/001—Random Hardware Failures & ALARP
  • Work Instruction xxx/002—Integrity Targeting
  • Work Instruction xxx/003—Life-Cycle Activities
  • Work Instruction xxx/004—Architectures (SFF)
  • Work Instruction xxx/005—Rigour of Life-Cycle Activities
  • Work Instruction xxx/006—Functional Safety Competence
  • Work Instruction xxx/007—Functional Safety Plan
  • Work Instruction xxx/008—Functional Safety Specification

1. Purpose of Document

This standard provides detail of those activities related to setting and achieving specific safety-integrity targets and involves the design, installation, maintenance, and modification stages of the life cycle. Where the activity in question is already catered for elsewhere in the XYZ Ltd quality management system, this document will provide the appropriate cross-reference.

The purpose of this procedure is to enable XYZ Ltd to provide in-house expertise in functional safety such as to meet the requirements of IEC 61508. Since IEC 61508 is not a prescriptive standard, the issue is of providing a risk-based “safety argument” that is acceptable to one's regulator/auditor/HSE. A functional safety assessment consists of evidence showing that the areas of the standard have been adequately addressed and that the results are compatible with the current state of the art.

This requires a proactive risk-based approach rather than a slavish adherence to requirements.

2. Scope

The standard shall apply to all products and documentation designed, produced, installed, or supported by XYZ Ltd except where contract requirements specifically call for an alternative.

In the case of simple designs, and modifications to existing plant, these activities may be carried using in-house resources and skills. Larger projects may require the use of external resources.

Additional detail (to assist Project Safety Engineers or subcontractors) is supplied in Work Instructions/001–/008.

The following diagram shows the relationship of relevant procedures:

3. Functional Safety Policy

Paragraph x of the Quality Manual emphasizes that capability in respect of functional safety is a specific design capability within XYZ Ltd. Some contracts will relate to safety-related applications. Some developments will specifically target safety-integrity conformance as a design requirement.

If the project is deemed to be safety related then the Project Manager shall appoint an independent Project Safety Assessor. However, a project may be declared sufficiently minor that formal hazard identification is not required and that the remainder of this procedure need not apply. That decision will only be undertaken or ratified by the Company Functional Safety Manager.

In the case of minor modifications this review process is satisfied by means of the impact analysis which shall be recorded on the change request.

4. Quality and Safety Plan

Every project shall involve a Quality and Safety Plan which is the responsibility of the Project Manager. It will indicate the safety-related activities, the deliverables (e.g., Safety-Integrity assessment report) and the competent persons to be used. The Project Manager will consult the competency register and will review the choice of personnel with the Safety Authority.

The tasks are summarized in Section 5 of this standard. Minimum safety-related items required in the Quality and Safety Plan are shown in Work Instruction/007.

See also Appendix 7 of this book .

5. Competencies

The HR department will maintain a “safety-related competence register” containing profiles of those individuals eligible to carry out functional safety assessment and design tasks. Periodically the Managing Director and Functional Safety Manager will review the list.

The list will be updated from:

• Individuals' attendance at relevant off-the-job courses
• Records of safety-related experience from each project (on-the-job training) (Project Managers will provide this information to the Personnel Manager)
• Details ...