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Local Fuel plc - Shoreham Oil Terminal
Safety Instrument System Functional Safety Assessment Stage 5
P & I Design Ltd
DOCUMENT NO: LF364100_RPT
2 Reed Street, Thornaby, UK, TS17 7AF
ISSUE: B DATE: 07.06.2016
Tel: + 44 (0)1642 617444
PAGE 15 OF 51
Fax: + 44 (0)1642 616447
www.pidesign.co.uk5.2.4
Is each SIF described adequately, together with a definition of the safe state. BS EN Clause
10.
Section 4.6 of the SRS provides information of the function and safe state.
5.2.5
Have common cause failures been considered. BS EN Clause 10.
Section 2.3 of the SRS details that the SIF’s are non-redundant and as such common cause
failure should not be an issue. However, although not really a common cause failure as such,
the failure of XV162 is common to all gasoline tanks and as such a total failure of this valve
will have the effect of preventing gasoline imports to both tanks.
5.2.6
Have process conditions been considered which could have an effect on the limitations of
sensors or final elements. (e.g corrosion, plugging, coating). BS EN Clause 10.
Section 3 of the SRS defines the conditions likely to have an effect of the SIS.
5.2.7
Are performance requirements defined. (e.g speed of closure of valve). BS EN Clause 10.
Section 4.6 of the SRS defines the requirements of slow closure of the final element to prevent
pipeline surge. As the actuator is electrically operated there should be no difficulty in
achieving the stated 90 seconds closure time. Section 2.3 defines that surge calculations have
been carried out but it does not define what the actual safe closure time is.
Action 3:
5.2.8
Are sensor inputs defined with respect to range, accuracy etc. BS EN Clause 10.
The SIF operates at a selected location in the tanks and as such is a switch, so no range is
required.
5.2.9
Have the process setpoints and trips been defined. BS EN Clause 10.
The process setpoint is provided in Section 4.6 of the SRS.