Proposed HSE guidelines on emergency shutdown systems

Modern programmable systems offer extremely high levels of reliability but require an appropriate level of attention to detail during design, manufacture, commissioning and operation to ensure high systematic integrity. The reliability of sensors and actuators on which emergency shutdown (ESD) systems depend entirely for safe plant operation will continue to be a limiting factor to the overall level of reliability achievable. Modern state-of-the-art technology and techniques however, such as addressable sensors with self-calibrating capability, and valve actuators with position monitoring can be applied to increase overall reliability. The cost of the features and the degree of redundancy throughout the system and hence further complexity needs to be balanced against the hazards and potential consequences of system failure. The ESD guidelines document should help both manufacturers and users to make these decisions and so take advantage of modern technology whilst improving overall plant safety