ABB Limited
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Tel: +44(0)1642 372000
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www.abb.comRegistration no:
Registered Office:
Pavilion 9, Byland Way
3780764 England
Daresbury Park
Belasis Hall Business Park
Fax: +44(0)1642 372111
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info@gb.abb.comDaresbury, Warrington
Billingham TS23 4EB
VAT Reg No:
Cheshire WA4 4BT
United Kingdom
668 1364 13
United Kingdom
The requirement for the class VI shut-off, was specified 6 years earlier and passed to the functional
safety team. There was no subsequent review of the SIF design and impact on the operating or
maintenance teams – a classic case of silo working.
Benefits of breaking down silos:
The impact of the high annual maintenance costs had prompted a revalidation exercise. During this
re-validation it was highlighted that the existing safety system would not achieve the intended
function and improvements had to be made. The requirement for the tight shut-off was challenged
and process engineering effort was invested into the process model. The outcome from the modelling
exercise demonstrated that a larger valve leakage rate could be accommodated without the resultant
runaway reaction. In addition, all the results from the previous valve leakage tests had met the
revised acceptable leakage rate.
Using the new safety requirements, information on the actual reliability of the valves and other
improvements in the basis of Safety, it was possible to extend the time between the valve overhaul
and leak test from annually to every two years. Enabling significant maintenance cost saving and
increased production uptime.