Puma Energy Rail Loading SIS

TRAC Safety Function Report

MURCO

MHR 5300

Business

Site

Rail Stand ESD

Default

Plant

Area

System Version

53LSH3071 RO 1 Rail Loading Arm Overfill Trip

1

Safety Function Associated Tags

(50LS3071) (53XV3079)

Safety Function Summary Page

Basic Information

Overfill of the rail car due to various initiating causes results in loss of containment of flammable hydrocarbon. Potential for fire/explosion resulting in serious injury or fatality of any vulnerable personnel. The Equipment Under Control will be the Rail Cars that are filled with finished product. Target IL Assessment To isolate rail loading arm on detection of high level in the rail car.

Scenario

Purpose and Requirement

Comments

Risk Type

LOPA

Risk Graph

Alternative

PFDavg 0.00100

IL

PFDavg 0.00050

IL

PFDavg

IL

Safety

SIL 2

SIL 3

Selected Target

Risk

IL

PFDavg

IL Assessment Justification: Overfilling of a Rail Car can lead to significant loss of containment of flammable hydrocarbon with a potential for serious injury or fatality of any personnel that may be exposed to the fire / explosion that could result in the event of ignition. The LOPA has determined that a SIL 2 instrumented function is required to reduce the residual risk.

Achieved IL Assessment

Achieved IL

SIL 2

Achieved PFDavg

0.00102

1 day 1 day

Input Test Interval(s)

3 Months

Output Test Interval(s)

MTTR

0.0082

Spurious Trip Rate

0.0423

Test Interval Justification: Rail Stand ESD valves are reset and tripped daily as required by the normal operating procedures using switch 53HS3096 in the Offsites Control Room. Use of the switch is data logged to allow monitoring to ensure proof test is performed regularly.

Maintenance Overrides provided to enable testing of inputs without disruption of normal operation. % Contribution (Inputs / Logic Solver / Outputs)

Comments

The Architectural Constraints for this Safety Function have been met

The Achieved IL MEETS the Target IL

Safety Function Summary Date Printed:18/05/2017 13:37

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The calculations within TRAC are in-line with those defined in ISA-TR84.00.02-2002 Part 2 ‘Safety Instrumented Functions (SIF) – Safety Integrity Level (SIL) Evaluation Techniques Part 2: Determining the SIL of a SIF via Simplified Equations’

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