hazards30 - icheme · 2020. 12. 11. · voting logic arrangements survivability requirements...
TRANSCRIPT
Hazards3026-27 November 2020
Guidance On Fire, Combustible Gas And Toxic Gas Detection System Development
Presented by Jonathan Wiseman of Risktec Solutions
Introduction
In August the Energy Institute published guidance on
fire, combustible gas and toxic gas system
development
Provides an adaptable methodology for the
development and maintenance of an effective and fit-
for-purpose F&G detection system
Aimed at:
Operators handling fluids with significant fire and gas
hazards
Those involved in facility hazard analysis and
performance standard development
Engineering designers
Regulators
Why guidance is needed?
Information overloadAbsence of guidance for
fire and gas detection
design in process areas
Variability of hazard outcome
Leak locations
x
Release directions
x
Hole Sizes
x
Wind Speeds
x
Wind Direction
x
Ignition?
The role of F&G detection
F&G detection:
Does not actually reduce risks
Has to interface with other systems / measures
for risks to be reduced
Forms part of consequence mitigation
Efforts should be prioritised to prevention (e.g. maintenance, process control / monitoring)
However, loss of containment risks cannot be eliminated and typically fire and gas detection provides our first means of identifying an incident has occurred.
Detect • F&G detection
Decide• Control
logic, operator decision
Action• Shutdown,
active fire protection
Complete Safety Measure
Methodology
Hazard assessment
Checklist:
Material properties (pressure, temperature, flammability, toxicity
etc.)
Nature of the release (high pressure jet, dense, buoyant,
vapourising pool etc.)
Potential consequence (e.g. congestion, vulnerable asset,
personnel)
Topography of the site
Air movements / dominant wind
Ignition sources
…or use assessment already undertaken for the facility (e.g. QRA or CFD)
Hazard assessment
Requirements can include:
Response times to initiate action
Alarm levels / sensitivity settings
Size of hazard (e.g. cloud volume, fire size)
Coverage requirements
Reliability, availability and maintainability
Voting logic arrangements
Survivability requirements
Interface requirements
The requirements must have clear pass / fail criteria so the performance can be
clearly assessed or tested.
Define detection requirements
Many different detector types, each with their own pros and cons.
Detector selection & technology
Detector positioning strategies include:
1. Volumetric monitoring: protection against explosion hazards,
also used for flame detection
2. Enclosure monitoring: protection of buildings
3. Source monitoring: protection at source (spot hazard detection)
4. Target receptor monitoring: protection of vulnerable / occupied
areas
5. Perimeter monitoring: protection against gas migration to
vulnerable location (e.g. public area or non-ex rated
equipment)
Detector layout strategy & placement
Once we have decided on an appropriate layout strategy, we are at a stage whereby we can position our detectors
The philosophy should identify the appropriate methods to verify that the
requirements are satisfied.
Coverage assessment approaches:
Qualitative
Geographic mapping: the fraction
of the volume covered by detectors
Scenario based mapping: the
fraction of the release scenarios
detected
All the techniques have strengths and weaknesses
The mapping technique should complement the detection requirements and in particular the
detection layout strategy
Performance assessment - coverage
Review of the performance of the F&G detection system should be
undertaken throughout the following stages:
Design (as part of design reviews)
Installation and commissioning
Throughout operations
Modifications must be controlled through management of change
process.
Ongoing review may include verification by a competent authority if
F&G detection is designated as a safety and environmentally critical
element (SECE)
System review
Summary
The document is intended to address a shortfall in terms
of guidance for implementation of fire and gas detection
systems, particularly in process areas
The reason for poor historical performance may be due
lack of a well defined method to designers
Having a structured process for F&G detection design
allows us to select the most appropriate detectors and
layout strategy for the dominant risks.
Allows us to organise the wealth of inputs to F&G
detection design into a practicable solution.
About Jonathan Wiseman
Jonathan Wiseman is a principal engineer based in Risktec’s
Warrington office.
He has over 14 years of varied risk management and technical safety
engineering experience, spanning high-hazard industries including oil
and gas, civil nuclear and defence.
Designing a F&G detection system is a significant challenge, but one
that can be made easier through application of structured
methodology. Jonathan worked with the EI to develop guidance to
provide a methodology for F&G detection implementation. The
guidance covers topics such as hazard assessment, setting of system
requirements, detector selection, assigning appropriate detector layout
strategy and performance verification. It is intended to offer a flexible
approach to F&G detector implementation, one that is relevant to
multiple hazard types across upstream, downstream, onshore and
offshore facilities.
Q&A
Thank you for your attention
Have a safe and secure day!
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