ABB Limited
Please reply to:
Tel: +44(0)1642 372000
Website:
www.abb.comRegistration no:
Registered Office:
Pavilion 9, Byland Way
3780764 England
Daresbury Park
Belasis Hall Business Park
Fax: +44(0)1642 372111
E-mail:
info@gb.abb.comDaresbury, Warrington
Billingham TS23 4EB
VAT Reg No:
Cheshire WA4 4BT
United Kingdom
668 1364 13
United Kingdom
To avoid duplication of effort, and enable the delivery of the lifecycle information in a format which is
easy for the operation and maintenance teams to follow, we need use systems which simplify the
recording process and can provide the visual formats such as bow-ties. These formats encourage
operator engagement and enables a clearer understanding of the first 2 questions i.e. the different
hazardous events and the barriers which are in place to protect against it.
The following is an example of a typical LOPA assessment:
Target IL Assessment Summary
Safety impact
Scenario
Blockage downstream valve fuel gas scrubber leading 4 times the design
pressure, failure of the vessel and large gas release.
Purpose and Requirement
To prevent overpressure detected by PSHH-001 and close XV-001 in 10 sec.
Risk Type
Safety
Assessment Date
dd-mm-yyyy
Consequence
Fire and or other explosion, potential for single fatality.
Severity
Cd (On-site fatality)
Target Frequency
1.0E-6
LOPA Assessment
Initiating Causes
Ref
Description
Freq(/yr)
Tags
Justification
A
Failure of Control System
0.2
PICA-123 Removed
B
Human Error
0.01
SOP-0001 Removed
C
Spurious Closure of a Downstream Valve
0.1
Removed
D
Blockage of the after filters.
F-111A&B Removed
Independent Protection Layers
Ref
Description
PFDavg
Tags
Justification
1
BPCS Interlock
0.10000
PIC-123
Removed
2
Operator Response BPCS Alarm
0.10000
PAH-321 Removed
3
Pressure Relief
0.01000
PZV-123 Removed
4
Occupancy
0.10000
Removed
5
Probability of Ignition
0.50000
Removed
PFDavg Calculation
Initiating
Cause
Freq
(yrs)
Independent Protection Layers
1
2
3
4
5
6
7
8
I.E.F(/yr)
A
0.2
1.00000 1.00000 0.01000 0.10000 0.50000
1.0E-4
B
0.01
0.10000 1.00000 0.01000 0.10000 0.50000
5.0E-7
C
0.1
0.10000 1.00000 0.01000 0.10000 0.50000
5.0E-6
D
0.10000 1.00000 0.01000 0.10000 0.50000
0.0E+0
Total Event Frequency Fe/yr.
1.1E-4
PFDavg for Safety Instrumented Function, Ft/Fe
9.5E-3
Safety Integrity Level =
SIL 2
To the untrained eye it can be difficult to disseminate the detail contained within this assessment.
However the use of new tools, enable the same information to be automatically represented in a
pictorial view where it becomes clearer of the important of each barrier in protecting against
individual hazardous events and enables operator engagement.