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ISA Automation Conference 2013- EMEA (Dammam, Saudi Arabia) – December 10-12, 2013

Optimizing Fire and Gas System Design Using the ISA Technical Report ISA TR 84.00.07

EDWARD MARSZALPresident and CEOSRINIVASAN GANESANMENA Region Manager

Presenter Introduction

• Edward M. Marszal, PE, ISA84 Expert• President, Kenexis• 20 Years Experience• ISA Author “SIL Selection”• ISA Committees - S84, S91, S18,

S84 WG7 Fire and Gas• ISA Safety Division Past Director• ISA Fellow• AIChE, NFPA Member• BSChE, Ohio State University

ISA84 Expert


Title

IntroductionMain Topics

• ‘Basis of Safety’• Prescriptive v. Performance Basis• FGS Design Lifecycle• Performance Target Selection• Detector Coverage Verification


‘Basis of Safety’ for FGS

• All critical instrumentation / control systems require a ‘basis of safety’• specify adequate equipment selection and design • specify functional testing requirements

• For fire and gas systems ‘basis of safety’ are developed in two ways:• Prescriptive ‘Basis of Safety’,

NFPA/EN standards, etc.• Performance Basis / Risk Assessment


• Well‐established guidance for design of detection and mitigation systems• Provide detailed requirements for basis of

safety for most types of FGS function• Do not provide detailed requirements for fire and gas

detection in chemical processing areas

• Allow for performance based alternatives to be used (where appropriate)

• Generally not specific to chemical processing

Prescriptive Standards in FGS Design


• ISA TR 84.07 Provides guidance for FGS design in accordance with the principles of ISA84 / IEC61511• Specify and Verify Performance Targets

• Availability (equivalent to SIL)

• Detector Coverage

• Written specifically for process industry

• Not intended as replacement forprescriptive design;intended as supplement

Performance-Based Standards


Fire and Gas Design Lifecycle


Identify Requirement for FGS

FGS Zone Definition

Determine FGS Performance Requirements

Verify Detector Coverage

Verify FGS Availability

Modify Design (if required)

Construction, Installation, And Commissioning

PSAT

Operation, Maintenance and Testing

Procedure Development

Management of Change

Design Specification

Develop FGS Philosophy

Typical Workflow for FGS Design


FGS Zone Definition

Verify Detector Coverage

FGS Toolkit

Task Tools DeliverableInput

FGS Zone List

PFDP&IDPlot/Deck PlanCause-and-Effect

FGSToolkit

FGS Design Basis Report

Effigy™ FGS Detector Mapping Report


Fire and Gas Performance Targets

FGS Philosophy& Procedure


Risk Modeling Requirements

• Desire a Risk Model that is sensitive to:– Detector Coverage– FGS System Probability of Failure on Demand

• Analysis Considerations include:– Hydrocarbon Processing Equipment – Fire and Gas Consequences– Release Likelihood– Level of Human Occupancy of Zone– Ignition Probabilities– Production Value for Process


• Two Common Approaches– Semi‐Quantitative

(Similar to LOPA)

– Quantitative Risk Analysis (QRA)

Performance Target Determination


Fully Quantitative Approach• Targets calculated through rigorous modeling

of hazards• Consequence characterized by

dispersion/consequence modeling• Release likelihood characterized by equipment

failure database• Mitigating factors characterized by site specific

factors• Calculated risk compared against tolerability

criteria• Design criteria are iteratively modified in order

to achieve the tolerable risk target • Analysis based on Scenario Coverage and safety

availability


Hazard Scenario Identification

• Hazard scenarios should include general release / fire scenarios– Identify all credible release scenarios, including:

– Vessels, process piping, flanges, instruments, wellheads, pumps, compressors, heat exchangers, launchers/receivers, risers and pipelines

• Identify specific factors effecting release scenario– Hole size, location, orientation, phase, toxicity (H2S),

occupancy• Result should be a detailed list of release scenarios with

enough detail to undertake consequence and likelihood analysis

• Identify potential incident outcomes:– Jet fire, Flash Fire, …..


Likelihood Analysis

• Based on Historical Offshore Data:– Offshore Release Statistics, 2001. UK Health

& Safety Exec.– PARLOC 2001: The update of Loss of

Containment Data for Offshore Pipelines. UK Health & Safety Exec.

• Sensitive to hole size distribution • Sensitive to Equipment Type

Fully-Quantitative Method


Risk Integration – Event Tree

Fully-Quantitative Method

Estimated Risk is greater than performance target, adjust parameters to achieve targets

Early Ignition?Release Detected? ("Detector Coverage")

FGS Effectiveness ("PFD") Delayed Ignition?

Residual Fire Detected

Residual FGS Effectiveness ("PFD")

Frequency (1/year)

SuccessYes 0.90.85

FailureYes 0.10.04

No0.15

Success0.9

Yes Success0.85 0.9

Release Yes2.97E-04 0.85 Failure

Yes 0.10.04

NoFailure 0.150.1

No0.96

No Success0.96 0.9

Yes0.85 Failure

Yes 0.10.04

NoNo 0.150.15

No0.96

Total 2.97E-04

9.10E-06

1.01E-06

1.78E-06

2.18E-04

7.43E-07

8.25E-08

1.46E-07

2.33E-05

1.31E-06

1.46E-07

2.57E-07

4.11E-05


Semi-Quantitative Approach

Grade Level of Risk Detection Coverage FGS Safety Availability

A High Risk 0.900.95 (High SIL 1 Equivalent)

B Medium Risk 0.800.90 (SIL 1 Equivalent)

C Low Risk 0.600.90 (SIL 1 Equivalent)

• Team‐Based approach employing calibrated risk assessment tables• Risk factors qualitatively ranked by team

• Likelihood• Consequence• Mitigating factors

• Selected categories determine the “zone grade”• Zone grade defines geographic coverage and safety

availability


Calibration

• Parameters and performance target calibrated by full QRA of typical zones

• Safety Availability and Geographic Coverage Set


• Define extents of area the overall zone that are required to be covered by fire and gas detection

• Limits analysis to location where risk is high• Function of process equipment with potential to leak

and process conditions• Similar to electrical area classification

Extents of Graded Areas

Grade AGrade BGrade C



FGS Design Basis Report

FGS Philosophy& Procedure

Effigy™ FGS Detector Mapping Report

FGS Toolkit

FGS AvailabilityReport

Verifying FGS Detector Coverage



FGS Toolkit

Verify Detector CoverageFGS Philosophy& Procedure


• Failure of Fire and Gas System to Function are related to one of two Mechanisms:

• Inadequate Coverage - Failure to detect hazard due to inadequate sensor type, number and/or location

• Inadequate Availability - Failure of component hardware to function as intended

• Proposed detector layout should be assessed to ensure adequate coverage:

• The coverage footprint is sufficient to provide the required hazard alarms and control actions

• Detector views are not impeded by pipework, cable trays and other obstruction

Why Verify Detector Coverage?

HSE Statistics Indicate that 36% of Major Gas Release in North Sea Offshore Installations are Not Detected by Gas Detection Systems

The Maginot Line


• Two methods of coverage verification are defined by ISA TR 84.07:• “Detector Geographic Coverage – The fraction of the geometric area

(at a given elevation of analysis) of a defined monitored process area that, if a release were to occur in a given geographic location, would be detected by the release detection equipment considering the defined voting arrangement.”

• “Detector (Scenario) Coverage – The fraction of the release scenarios that would occur as a result of the loss of containment from items of equipment of a defined and monitored process area that can be detected by release detection equipment considering the frequency and magnitude of the release scenarios and the defined voting arrangement.”

Verifying Detector Coverage for Process Areas


FGS Detector Mapping Assessment

• Detector Performance characterized based on data from FM approval testing

• Detector Coverage calculated based on 3-dimensional modeling

• Achieved coverage is compared against performance target

50 %Sensitivity

100 %Sensitivity

75 %Sensitivity


FGS Detector Mapping AssessmentGeographic Fire Detector Coverage

Geographic Gas Detector Coverage

Scenario-Based Geographic Risk

Scenario-Based Coverage



FGS DetectorMapping Report

FGS DetectorLocations

FGS AvailabilityReport

FGS Toolkit

FGS Performance Specifications

FGS Toolkit

Verifying FGS Availability

Modify Design (if required)

Effigy™

Verify FGS AvailabilityFGS List


Parameters Impacting Availability


Construction, Installation, And Commissioning

PSAT

Operation, Maintenance and Testing

Procedure Development

Management of Change

Design Specification

Implementation Phase

• Prepare detailed design documents based on FGS SRS

• Verify and validate prior to startup

• Perform ongoing maintenance and testing as required

• MOC is important! Many plant changes impact coverage


Questions?

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