Identifying & Mitigating Risks – Are we really getting better?
Post on 25-Mar-2023
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The Importance of Risk Assessment
• 1988- The world witnessed the most devastating off shore disaster when an explosion on oil rig Piper Alpha caused a fire killing 167.
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• 1980 - The Alexander L Keilland rig in the North Sea's Ekofisk field –capsized , breaks up after a fatigue fracture - 123 killed.
• 1984 - A blowout on the Petrobras in Brazil caused an explosion and a fire - 42 workers died
• 1988 - Piper Alpha Oil Rig: Gas Leak-167 people killed• 1995 – Mobil Oil rig explosion off coast of Nigeria – 13 killed• 2001 - Explosion on the P-36 offshore production platform. 11 People
Killed. 10,000 barrels of fuel and crude spilt into the Atlantic• 2005 - fire destroyed the Mumbai High North processing platform -22
people killed• 2010 - Explosion and fire on the Deepwater Horizon drilling rig -11
workers killed 5 mile oil slick• 2012 (Aug 25) - A blast at the Amuay oil refinery in Venezuela kills
nearly 50 people• 2012 (Sep 18) - A fire at a PEMEX compressor station near Reynosa in
northern Mexico kills 26 people
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• Technology has advanced, but we are still seeing disasters strike.
• 2010- The worst Oil Spill in US history• 11 Lives Lost• 4.9 million barrels spilt
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Industry Comparisons
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Nuclear
Windscale 1957
Idaho Falls 1961
3 Mile Island 1979
Chernobyl 1986
Fukushima 2011
Transportation
Tenerife 747 1977
Clapham Junction 1988
Zeebrugge 1989
Ladbroke 1999
Uberlingen 2002
Canada Train 2013
Process
Flixborogh 1974
Bhopal 1984
Phillips 1989
Buncefield 2005
Waco 2013
Mike JonesChief Consultant CRA – Industrial Process Assurance• 40+ years experience in Industry/HSE/Consultancy• Operations, Operations Management, Control Systems• HSE Specialist Inspector (Process Safety)• Process Safety Consultant
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ABOUT YOUSome quick questions…• Chemists• Chemical Engineers• Mechanical Engineers• Chemicals• Petrochemicals• Offshore
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SEVESO II Directive
• Implemented in UK as the Control of Major Accident Hazards Regulations 1999 (COMAH)
• Subsequently amended 2005 and just when you thought it was safe to leave your safety report….(Seveso III is due in 2015)
• Regulation 2 – contains the definition of a major accident…what are the three important criteria?
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SEVESO II Directive
• an occurrence (including in particular, a major emission, fire or explosion) resulting from uncontrolled developments in the course of the operation of any establishment and leading to serious danger to human health or the environment, immediate or delayed, inside or outside the establishment, and involving one or more dangerous substances
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Major accident means…
PLANT MODIFICATIONS
• Key Risk Control System■ Identify as modification■ Assess appropriately■ Record all information
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Some History…Flixborough 1974• Large scale fire and explosion at Nypro nylon plant• Killed 28 people• Blast damaged property over two miles away
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Some History…Flixborough 1974• Nypro plant was producing nylon 6,6• Raw material was cyclohexane (a HFL)• First stage was air oxidation of cyclohexane• High temperature and pressure• There had been a plant modification…
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Some History…Flixborough 1974• Failure of a temporary plant modification (bellows)• Modification ill conceived and poorly designed• This would have constituted a Major Accident as defined
in COMAH• Could something like this be repeated?
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Plant DetailsWilton Nylon (KA) plant (2006)• COMAH Top Tier Establishment• Plant modification to alter plant chemistry, improve
throughput and re-utilise a 100m3 vessel.• Modification was subject to extensive risk assessment
(HAZID and HazOp study types).
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The ProcessWilton Nylon (KA) plant (2006)• Oxidation of cyclohexane by air• High temperature (150C)• High pressure (7.5 Barg)• High plant inventory (1200 tonnes)• High flow rates (>100 tonnes per hour)• This is how the process looked…
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Incident Details
• 13mm nut fell off an agitator skirt support.• Eventually resulted in loss of a significant amount of
cyclohexane vapour at high temperature and pressure.• What happened in between?
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Incident Details
• 05:54 a.m. Sunday 19th February 2006 (shift changeover)
• Between 10 and 24 tonnes cyclohexane vapour released• Vapour at 150C and 6.7barg pressure• Release vapourised and entirely filled plant structure
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Incident Details
• One of the guard oxidiser agitator skirts dropped and fouled on it’s support stool
• Extreme vibration set up on shaft (screaming sound heard) over a five minute period
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Incident Details
• There was a 16” flange housing the agitator seal• The 12 x 25mm flange bolts holding the agitator seal in
place all loosened over a five minute period
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Incident Details
• The loosened flange acted in the same way as a relief valve
• The agitator seal did not initially fail• There was no ignition...
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Incident Consequences
• This was a COMAH major accident…• The accident was reported to the EU:
http://www.hse.gov.uk/comah/eureport/car2006.htm
• A COMAH Prohibition Notice was issued:http://www.hse.gov.uk/NoticesHistory/notices/Notice_details.asp?SF=CN&SV=302488293
• The plant was shut down• The COMAH Prohibition Notice was lifted after about
two weeks• What went wrong?
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Learning PointsSite Specific• Fully review all the changes to equipment
(motor/gearbox over rated for new duty)• Provide instrumentation to monitor (agitator)
motor performance• Mechanical integrity –
Have consistent bolting standards
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Learning PointsGeneral• Review inspection results• Link the major hazard risks with the causal plant
risks (Seveso III)• Emergency response learnings
• Any questions?
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OUR SERVICES
• Industrial Process Assurance• Human Factors• Environmental & Decommissioning• Reliability & Maintainability Analysis• QRA• Safety Case
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