Functional Safety 2016

ABB Limited

Please reply to:

Tel: +44(0)1642 372000

Website:

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Registered Office:

Pavilion 9, Byland Way

3780764 England

Daresbury Park

Belasis Hall Business Park

Fax: +44(0)1642 372111

E-mail:

Daresbury, Warrington

Billingham TS23 4EB

VAT Reg No:

Cheshire WA4 4BT

United Kingdom

668 1364 13

United Kingdom

It is clear that the risk assessment in this case should not allow the bypass to be put in place until the

earlier protection layers are reinstated. This information should also be made available to the person

carrying out the SOP, highlighting that a mistake at a critical step is likely to place a demand on the

safety system and potential plant shutdown.

A similar example demonstrates how the same information can be used in the avoidance of plant trips.

In this scenario, the interlock is manual and the alarm is in an active alarm state, but has not been

responded to. Representing the information in this format enables clear visualization that the next

available barrier is the SIF, which if activated will initiate a plant trip. This provides the necessary

decision support to prioritize operator actions, initiate the corrective actions to put the process into the

back into the operating envelope and enable plant production to be maintained.