IS YOUR CONTROL SYSTEM SAFE? - ASKS HSE PUBLICATION

HSE Press Release - E047:04 15 April 2004

The Health and Safety Executive (HSE) has recently updated its popular guide aimed at managers, engineers and technicians with responsibility for safety-related control systems in any industry.

Out of Control: Why control systems go wrong and how to prevent failure (2nd Edition) features a description and analysis of 12 incidents. In these, control system failures caused fatal crushing, amputation, physical trapping, microwave injury, gas releases, an acid spillage, the listing of a drilling rig and the malfunctioning of a radiation shield.

The guide shows how the incidents could have been prevented by the application of straightforward precautions and a summary of a further 22 incidents lists primary and secondary causes. Together, these results reveal the relative importance of each activity in a typical development lifecycle.

For the 34 incidents analysed, 44% had inadequate specification as their primary cause. The other results were 20% changes after commissioning, 15% design and implementation, 15% operation and maintenance and 6% installation and commissioning. This means approximately three-fifths of all control system failures are built-in before operation commences.

As technology advances our lives depend more and more on the correct operation of electrical and electronic control system. An understanding of how and why electrical and electronic control systems fail can help prevent further incidents in future.

Paul Davies, HSE's Chief Scientist commented, "This guidance allows everyone involved with the development and use of control systems to learn from others and avoid repeating disastrous mistakes. It provides a good introduction to the issues to consider when building and relying on a control system for safety, and points to many sources of further information."

Copies of 'Out of Control: Why control systems go wrong and how to prevent failure (2nd edition)', (HSE ref: HSG 238) are available from HSE's website.

Notes to editors

1. The 2nd edition contains a comprehensive revision of references and some minor changes to the guidance in the first edition, published in 1995.

2. The guidance takes the lifecycle development approach required by many national and international guidelines and standards, including IEC 61508, Functional safety of electrical/electronic/programmable electronic systems and IEC 61511, Functional safety - Safety instrumented systems for the process industry sector.

3. An electronic file of the cover image can be supplied upon request.

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