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case study -revisited
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1988: Piper Alpha Oil Rig Ablaze
CHEN 655 Project:Syed QuraishyTasmia Tahsin Priyanka
Piper Alpha-Location
At around 110 miles north-east of Aberdeen in the North Sea.
Claymore and Tartan were the two other platforms connected to Piper which were also operated by Occidental.
http://www.brighthubengineering.com/marine-history/116049-piper-alpha-oil-rig-disaster
Piper Alpha-Background
• Owned by a consortium consisting of
-Occidental Petroleum (Caledonia)
-Texaco Britain Ltd
-International Thomson Plc
-Texas Petroleum Ltd
• Oil Production in 1976 about 250,000 barrels per day increasing to 300,000 barrels later.
• In 1980 a gas recovery module was installed .• Production declined to 125,000 in the year
1988.
Piper Alpha-Background
• The production deck level consisted of four Modules:
Module A: Well head
Module B: Oil Separation
Module C: Gas compression
Module D: Power generation and Utilities
Piper Alpha-Background
Piper Alpha Platform: West Elevation
(Lee’s Loss Prevention in Process industries, Volume 3)
Piper Alpha Platform: Production deck on 84 feet level
Piper Alpha-Timeline
Incident Investigation1 hr. 35 min before disaster:
All gas alarm came from module C
Captain in one of the nearby ship had seen a blue flame coming underneath the module C
Convinced the investigator that module C was starting point of the explosion
Analyzing 3 products of Piper Alpha they were confirmed that condensate started the fire.
Incident Investigation Analyzed the pattern of the gas
alarm & suspected a condensate release in the eastern end of module C.
Only source of condensate in module C is two PSV’s; designed to withstand twice the operating pressure.
PSV-504 was taken out for a maintenance work, replaced by a blind flange/metal disk
Incident Investigation Workers had installed the metal disk by
hand tight. PSV-504 was connected with a condensate
pump which was shut down for an overhauling job.
Standby pump (Pump-B) tripped that night and the lead operator (unaware about the PSV maintenance work) had swapped the pump & introduced condensate for priming before startup.
Later when they had started the pump the leak was larger and triggered multiple gas alarms including the High gas alarm
1 hr. 30 min before disaster:
Module C was protected by fire walls designed to resist intense flames up to 6 hrs. but not explosion proof.
Destroyed the fire panels of the fire walls which had flown like projected missiles.
Damaged another condensate pipeline in module B.
This leak aided a second explosion which was an oil explosion resulted in an evanescent fire ball.
Incident Investigation
Incident Investigation1 hr. 10 min before disaster:
Colossal explosion from the bottom of module B had shaken the platform
Oil was dripping below the module B did not dripped directly to the sea but it settled
Divers placed rubber matting over the gratings to avoid the sharp edge on their bare feet
Dripped oil had formed a small pool and this pool fire had heated up a high pressure gas line from Piper alpha to another rig named Tartan.
The pool fire, weak metal, high pressure heated up gas caused the huge explosion and around 150m (as per Cullen Report) fire ball
Incident Investigation HP gas pipeline to Claymore destroyed Living quarter dislodged to the sea with
all the crew
Failure Analysis & Mitigation
PTW System• Multiple PTW should be kept at a common place• Proper hand over between shifts• Effective site auditing regarding specialized permit• Appropriate equipment specific isolation procedure
Fire wall and Layout
• Conducting a design safety review before any modification and analyzing the requirement of passive fire protection (blast proof walls) due to the new modification.
• Conducting Explosion Overpressure Study to check the extent to which the walls could withstand explosion
Failure Analysis & Mitigation
Automatic water deluge
system• Putting the critical safety equipment always on
automatic mode
Production-Safety Conflict
• People > Environment > Asset > Revenue
OSHA PSM Elements Failure
The 14 key elements of OSHA PSM are as follows: Employee participation Process safety information Process hazard analysis (PHA) Operating procedures Training Contractors Pre-start up safety review Mechanical integrity Hot work permits Management of change Incident investigations Emergency planning and response Audits Trade secrets
OSHA PSM Elements Failure
The 14 key elements of OSHA PSM are as follows: Employee participation Process safety information Process hazard analysis (PHA) Operating procedures Training Contractors Pre-start up safety review Mechanical integrity Hot work permits Management of change Incident investigations Emergency planning and response Audits Trade secrets
Accidents and disasters are common events in chemical, oil & gas, manufacturing, and nuclear industry.
Piper Alpha Disaster was initiated & propagated by faulty actions of human.
In our study of this incident we have focused on Human Error.
Our Approach
Human Error“Departure from acceptable or desirable
practice on the part of an individual that can result in unacceptable or undesirable results”1
Intentional & unintentional manmade mistakes that cause injury to people, environment pollution, economical loss and reputational damage.
It is a concept for explaining breakdowns, accidents or other inadvertent consequences .
1Bea, Holdsworth, and Smith, “Human and Organization Factors in the Safety of Offshore Platforms
Human error includes:
Failing to execute or omitting a task Accomplishment of the task inaccurately Performing an additional or non-required
task Performing tasks out of sequence Failing to perform the task within time limit
linked with it Failing to respond effectively to an
emergency
Human Error
Human Error Classification
Unsafe Acts
Intended Action
unintended Action
Slip
Laps
Mistake
Violation
Attentional FailureIntrusionOmissionReversal
MisorderingMistiming
Memory FailureOmitted Planned items
Place-losingForgetting intensions
Rule-based MistakesMisapplication of good rule
Application of bad ruleKnowledge-based Mistakes
Many variable forms
Routine ViolationExceptional ViolationArt based mistakes
Fig. 1: Unsafe Acts taxonomy (Reason 1990)
Slips: Errors associated with the execution of faulty action.
Lapses: Errors is caused by memory failure.
Mistakes: Error occurs perfect execution of a task but wrong planning.
Violations: Errors associated with deliberately avoiding organizational rules and regulations.
Human Error Classification
Human Error Classification
Human Error
Handling Error
Maintenance Error
Assembly Error
Design Error
Installation Error
Inspection Error
Operator Error
Control Error
Fig. 2: Human Error in Different Phase of a Project
Contributors to Human Error
Performance requirements that exceed human capability
Design that promotes fatigue Inadequate facilities or information Difficult/ Dangerous/ Unpleasant/
Repetitive tasks Tasks at odds with the person's aptitude Stress, Illness, Sleep Deprivation, Injury.
Human Error Management Reduce error vulnerabilities to tasks/task
elements Determine, asses & eliminate error
producing factors within the workplace Identify organizational factors that create
error producing conditions within the individual, team, task & workplace
Enhance error detection Increase the error tolerance of the system Improve the organization resistance to
human fallibility
HEART: Human Error Assessment & Reduction Technique
Established by J.C. Williams (1986)Procedural technique that attempts to
calculate human error. Data based structured approach to human
error quantification Uses its own values of reliability & also
“factors of effect” for a certain number of error producing conditions
Start
Analyze task by using HTA
Take the first/next task step from the
HTA
Assign a HEART generic category to
the task step in question
Assign a nominal human error
probability (HEP) to the task step in
question
Select any relevant error producing
conditions (EPC’s)
Take the first/next EPC
Determine the assessed proportion of effect of the EPC on the nominal HEP
Are there any more EPC’s?
YN
Calculate the final HEART HEP for the
task step in question
Are there any more task steps?
NY
Stop
HEART Methodology
Step 1: Categorized task Analysis (HTA)Step 2: The HEART Selection ProcessStep 3: Classification of task unreliabilityStep 4: Identifying Error Producing Conditions (EPC)Step 05: Assessed proportion of effectStep 06: Explanation of remedial measuresStep 07: Documentation
Human Errors in Piper AlphaPerforming a maintenance work without
following appropriate procedureFaulty warning system & read out problems
in the control board panel due to design of the panels or action of board operator
Put the automatic (electricity driven) firefighting pumps turned off
Philosophy of production first rather than safety first
Action of a less trained people as major decision maker
Assumed ScenarioA key overhauling work, already in backlog No practice of cross referencing between
works Possibility weather condition changeComplacent attitude in the auditing &
inspection practice. Non redundant methanol system (hydrate
inhibitor) needs troubleshootingRecently promoted OIM having no
experience in managing crisis condition as an incident commander.
General task category
Type of task (E) Routine, highly practiced, rapid task Involving relatively low level of skill
Nominal Human Unreliability 0.02
Error Producing ConditionsEPC HEART
effect (E)
Assessed Proportion
(P)
Assessed effect
A.E=((E-1) x P) + 1
No means of conveying spatial
and functional information to
operators(in this case
maintenance crew) in a form
which they can readily
assimilate
X 8.0 0.15 2.05
The need to transfer specific
knowledge from task to task
without loss
X 5.5 0.2 1.9
Little or no independent
checking or testing of output
X 3.0 0.5 2
Ambiguity in the required
performance standards
X 2.5 0.35 1.525
A need for absolute judgments
which are beyond the
capabilities/experience of the
performer
X 1.6 0.25 1.150
No obvious way to keep track of
progress during an activity
X 1.4 0.5 1.2
Human Error Probability
Nominal likelihood of failureP = Calculated Human Error Probability (HEP) is
nearly 33% for this particular task
Remedial MeasuresSpatial & Functional Incompatibility Such incompatibilities should not occur. If there is any
doubt expert opinion should be obtained to run the task in
appropriate manner
Knowledge Transfer Reliance should not be placed on operators transferring
their previous knowledge without loss of precision or
meaning-if such perfect transfer is required suitable job aids
should be provided as reference.
Inadequate Checking When high reliability is paramount, independent checking on
a proper accuracy level by people & systems that do not
have any vested interest in the success/failure of an
individual. Blame game is strictly prohibited.
Ambiguity It needs to be ensured that all the performers of a particular
task are well aware of the codes & standards. There should
not be any chance of relying on substandard information
Requirement of absolute judgment Task performer should not be placed in the position of
taking decision about issues which are outside the span of
their experience. Task analysis will help to figure out the
time when this sort of situation arises & management should
have contingency plan. Brain storming or problem solving
sessions can help to tackle this bizarre condition.
Lack of progress tracking Job aids (checklist/electronic mimic) need to be supplied in
order to ensure that performers do not go out of step with
the task in hand.
HEART at a glance
HEART method was used for error probability assessment & error reduction.
HEART provided valued awareness regarding industrial parameter
Aided to figure out appropriate defenses against human error in both qualitative & quantitative level.
AftermathImmediate wide ranging assessments of the installation
and management system carried.Official public inquiry of the disaster was done by Lord
Cullen came up with 106 recommendations. The Offshore Installations (Safety Case) Regulations
came into effect 1992The Offshore Installation and Pipeline Works
(Management and Administration) Regulations 1995 The Offshore Installations (Prevention of Fire and
Explosion, and Emergency Response) Regulations 1995 (PFEER)
The Offshore Installations and Wells (Design and Construction, etc) Regulations 1996
Survivors Psychology
Professor David Alexander carried out a study on the long-term psychological and social effects of Piper Alpha on the survivors.
Around 70% survivors had psychological and behavioral symptoms of post-traumatic stress disorder.
They had difficulty in finding employment.Employers regarded Piper Alpha survivors as
Jonahs – bringers of bad luck.Family members of the dead and survived victims
suffered psychological and social problems.
Piper Alpha Today
• Platform that used to produce 10 percent of the North Sea’s oil , today only a wreck buoy of it is all that is visible.
• A memorial sculpture showing three oil workers was founded in the Rose Garden within Hazlehead Park in Aberdeen.
• A scholarship was launched on April 20th 2011 by Industry Skills and Safety Body OPTIO as a tribute to the heroes of Piper Alpha who lost their lives.
• “Pound for Piper Memorial” was launched on the 28th of May 2012 to raise £1m for maintenance of the Piper Alpha Memorial garden.
• A three-day event to be held at Aberdeen which will be chaired by Oil & Gas UK chief executive, Malcolm Webb to mark 25 years of Piper Alpha disaster
This Presentation is dedicated to all the
survivors- “When I stand before thee at the day's end, thou shalt see my scars and know that I had my
wounds and also my healing.”-Rabindranath Tagore
THANK YOU