Discipline guidance - Control & Instrumentation

Guidance for assessment of C&I issues in COMAH reports

Introduction

This guidance assumes that the assessor is already familiar with control systems issues as applied in COMAH sites. A working knowledge of the principles contained in standards concerned with the design of control systems is required, and an understanding of BS IEC 61511 in particular is recommended. For an overview of C&I issues, see the Control Systems as part of the Technical Measures section of this manual

The aim of this guidance is to assist consistency in COMAH assessment by suggesting what sort of information should be included to make the key demonstrations.

The framework links information already present in the SRAM with the requirements of accepted good practice such as that found in BS IEC 61511. This standard had been referred to because of its close fit with the requirements of COMAH legislation. For those sites using other standards, see Guidance for Retrospective Application and Non 61508 Based Standards on COMAH Sites.

Much of the information required by a full BS IEC 61511 design lifecycle is also required as a part of the COMAH process, and so by adherence to this standard, COMAH sites should find that they are able to efficiently comply with the requirements to make the necessary COMAH demonstrations.

Conversely, where a site has used no specific standards in the past, BS IEC 61511 offers a convenient framework for assessment and inspection work.

In addition to the core C&I issues, the requirements of BS IEC 61511, if followed, should also assist companies with their demonstrations of SMS and Process Safety issues.