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Hazardex 2017 Conference - Installed (Legacy) Safety System Management

Author : Dil Wetherill - Risknowlogy

04 November 2016

Many safety systems in operation on the UK’s process plants were designed and installed prior to the development of IEC 61508 and IEC 61511. Many were installed after the introduction of these standards, but they were not compliant. There is an increasing focus on these “legacy” systems, but are they really providing the risk reduction that they should? 

This is a fundamental question for any safety system - and should also be applied to those systems which were compliant (or supposed to be) when installed. Are they still providing the risk reduction they should? So we should consider all “installed systems”, however old they may be, and irrespective of what standards and procedures were followed at the time of installation.

The UK HSE have commissioned CDOIF to develop guidance for operators in this area, in conjunction with bodies such as the InstMC Safety Panel, on which the author sits. The proposed presentation will reference the guidance from HSE / CDOIF and over-lay this with practical, real-life experience of carrying out installed system reviews with end-users.

The scope is simple to express - how much risk reduction do you need, is your safety system providing enough and do you have the systems in place to make sure it keeps providing it? But answering these questions is not so easy when documentation may be lost or not fit for purpose and when older systems may have evolved so that they are now combination of pneumatic, hydraulic and programmable electronic technologies.


If we assume that re-HAZOP and re-LOPA are routinely carried out, the presentation will address “what comes next”: Developing a summary SRS, carrying out validation by way of a suitable proof test, confirming the PFD by a range of means and putting in place the systems and procedures that will ensure the system continues to do what it should.

About the Speaker

Dil Wetherill is a Functional Safety Expert, chair of the 61508 association, a Fellow of the InstMC and sits on the latter’s safety panel. He is also a BSI UK Expert – IEC MT 61511, GEL/65/1, representing the UK in the development of IEC 61511.

Wetherill is managing director of Risknowlogy Ltd, which provides training, consultancy and certification services in the fields of risk, reliability and safety. He has a Masters Degree in Electrical and Electronic Engineering, is a Chartered Engineer and worked in functional safety for MTL and GE Intelligent Platforms before starting Risknowlogy in the UK.


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