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ABB GroupJune 19, 2013 | Slide 1
Periodic Hazard Review as anessential part of your PSM system
Gerry Brennan, Lead Principal Consultant, ABB Consulting / Piper 25 Conference June 18-20 2013
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Periodic Hazard Review as anessential part of your PSM system
Contents
Process Safety Management
Need for periodic hazard review
Techniques: HAZOP vs HAZID
Learning points from experience ofperiodic hazard review
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Process Safety versus Personal Safety
Major
Accident
Hazards
Slips, trips
and falls
Very
Unlikely
Possible
ProcessSafety
Personal
Safety
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What is Process Safety?
The prevention of unplanned & uncontrolled loss of
containment from plant and process equipment that
might cause harm to people or the environment.
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Learning
phase
Hardware wearout
Loss of corporate memory
Change in people
Creeping Changes in plant
Why is periodic hazard identification and risk analysis needed?
HAZOP Ongoing risk assessment?
Accident
Life of Plant
Plant
Safety
Performance
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Objective for Periodic Hazard Review
Evaluate controls for the hazards of the process as they
are currently understood
because
Process changes have introduced new hazards
New knowledge on hazard consequences is available
Recent incidents have revealed new scenarios
Barriers previously credited have changed
ABB GroupJune 19, 2013 | Slide 7
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HAZOP or HAZID?
Loss of
Containment
FAULT TREEEVENT TREE
HAZID
CAUSES
CONSEQ
UENCES
Mitigation
Measures
Prevention/Control
Measures
HAZOP
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Methodology
1. Split process into sections;
HAZOP node is a process line
HAZID node is unit operation, typically 1 or more P&IDs
2. Describe design intent for node;
operating parameters
key aspects of process control system
protective systems, trips/relief's/bunds
3. Apply guidewords - can it happen?
4. Assess consequences - does it matter?
5. Assess design safeguards - are they adequate?
6. Agree actions required to reduce risk
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HAZOP Guidewords (IChemE)
No (not, none)
More (more of, higher)
Less (less of, lower)
As well as (more than)
Part of
Reverse
Other than
Earlier/later than
With appropriate process parameter
Flow
Pressure
Temperature
Level
Concentration
Mixing
Etc.
Look for deviations from intent
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HAZID Guidewords
Burst Internal Explosion
Overpressure
Runaway Reaction
Puncture
Impact
Weakening
Corrosion
Wear
Temperature extreme
Openings
Vent/Drain
Overflow
Flange/Seal Look for causes of Loss of Containment
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Comparison application to offshore installations
Re-HAZOP of UK and overseas platforms during 2010-
2013
Hazard Study Equivalent days per platform: 90-150
Recommendations for improvement: ~500
HAZID of UK Platforms during 2011-13
Hazard Study Equivalent days per platform: 15
Recommendations for improvement: ~100
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Learning Points fromexperience of periodichazard review
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1. Write down clear Terms of Reference
Scope of review; what is included/excluded
Timescale; duration of commitment;
Team leader; competence
Hazard study team; essential disciplines
Method; guidewords, recording detail, recording tool;
stipulations about safeguards
Time required; hours of work; how many days per week?
Meeting room; lighting; space; projection; away from the
installation Data Gathering; up to date PIDs, process information;
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2. Specify the right team
Leader
Operations Manager Operator or Supervisor
Process,
Engineering /
Maintenance
Independent
Team Member
Other specialists as required
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3. Choose process node carefully
HAZOP: line or vessel HAZID: system by system
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4. Correct level of detail in records
Example of poor recording
GW Cause Consequence Safeguard Recommendation
No Flow Valve closed , etc Overpressure of Vessel XXXX Alarm and trip Consider pressure relief on
Vessel xxxx
Individual causesshould be
detailed. Manualvalve HVxxx
closed throughhuman error, ORFlow control
failure FICxx, ORspurious closure
XV xxx
Sequence should bedeterminedTellthe Hazard story.No flow causing
build up in pressurethis will be slow as
feed is low at y
m3
/min.Overpressuremaximum up to 4xdesign, but as slowrate of pressure riseline leakage at 2 to3x design. Release
of flammablesubstance into localprocess area. 1 to 2fatalities if ignitednormal occupancy.
Separatesafeguards.
Alarmresponse
detailed. Trip
tags andactions.
Consider should beavoided. Should
detail HAZOP teamconcernNormaldesign practice to
have pressure relief.Should be a review
to determine if reliefis required againstdesign requirements
and protectionrequired to avoid
fatalityconsequences.
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5. Recording:Can Link Hazop to bow tie
GW Cause Hazard Consequence Sev
erity
Safeguard L R Recommendation
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6. Hazard Study Recommendations
Need to carefully word to avoid confusion
Person given action may not have been at the meeting
Use what wherewhy format
Add instructions for securing of double block and bleedisolations on the fuel gas supply line XYZ123 to theBurner 1-B-07 prior to maintenance into plant operatinginstruction 23, in order to protect against the flow of fuelinto the burner and risk of explosion at start-up
Limit the number of actions generated
Complete simple design checks before report is issued
Keep a separate list of observations for project team
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7. Hazard study followed by LOPA
Hazard study provides the list of initial failuresand the risk screening to pick out significant
hazard scenarios
Layer of Protection Analysis (LOPA) provides
a more detailed risk estimate
Increasingly applied where there is a
significant consequence or a Safety
Instrumented Function
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7 Cont: But there some points to bear in mind..
Scope of LOPA: Only those with a SIF? Which severity level?
If HAZOP records are sketchy, lengthy discussion in LOPA is likely
Failure sequence not quantifiable: Must be an equipment or human failure
Poor: Operator error
Good: Block valves HV1 and HV2 left closed after maintenance
Poor logic in HAZOP: e.g. failure of a safeguard as cause
Failure to determine ultimate consequence and hence all safeguards
SIF cant be identified as no tag number on HAZOP record
Also other safeguards, e.g. alarms, procedures, relief systems
LOPA is top down from hazardous event, HAZOP is bottom up from cause
Need to cross reference all causes in HAZOP record
ABB GroupJune 19, 2013 | Slide 21
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8. Evergreen Records and revalidation programmes
Goals:
Accurate, current, detailed description of hazards and
safeguards available for reference in ORAs, MOCs
Reduce resources demanded for periodic process
hazard review Method:
Update the periodic review record with
Recommendations Closures and risk assessment
results (such as LOPA);
Revalidate the periodic review of hazards, every 5
years
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8 Cont.: Revalidation Method
Select first node
Ask the following questions
Have all the recommendations been completed?
Have the changes since the baseline Hazard Study been fully assessed?
Have there been any relevant process safety incidents, has the learning
from these been acted upon?
Are there any current concerns?
Is there any new knowledge or relevant good practice applicable to this
node?
In view of the above, does the hazard study need repeating? Repeat over all nodes
Table updated and new recommendations in the revalidation report
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ABB GroupJune 19, 2013 | Slide 24 ABB GroupJune 19, 2013 | Slide 24
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