hitchhiker's guide to bow ties

Hitchhiker's Guide to Bow Tie Risk Analysis for the new comers to Major Accident Hazard Industries

Shailesh Purohit: CMIOSH/ AMIChemE

Process Safety Engineer CLH Pipeline System Limited

160429 Hitchhiker's Guide to Bow Ties r0.pptx Hitchhiker's Guide to Bow Ties

Acknowledgments

• I wish to thank CLH-PS Limited for permitting me to conduct this workshop.

• I with to thank Risktec and CGE for their permission to use some of their training materials. Further information is available from their websites:

• http://www.risktec.co.uk/

• http://www.cgerisk.com/

• Last but not the least, I wish to thank the Hazardous Industries Group (HIG)Committee and IOSH Staff for their help and guidance in presenting this BowTie workshop.

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http://www.risktec.co.uk/

http://www.cgerisk.com/


Who are we?

• CLH Pipeline System (CLH-PS) Ltd is an oil product logistics company wholly owned by CLH that carries out its activities in the United Kingdom.

• CLH-PS provides its services to several military facilities and some of the main airports in the United Kingdom. It is the main fuel pipeline and storage facility network in that country.

• Its infrastructures consist of a pipeline network of 2,000 kilometres, which represents 50% of the British pipeline network, and 14 storage facilities with a total capacity of over one million cubic metres.

• CLH-PS supplies 35% of the demand for aviation fuel in the United Kingdom. Heathrow, Gatwick, Stansted and Manchester are among the main airports it supplies, in addition to other 10 regional airports that are supplied by road tanker.

• CLH Pipeline System is currently carrying out a major modernisation programme in its infrastructures with the aim of improving safety and efficiency and reducing costs.

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Introduction

• This presentation is to provide a brief overview of a “Bow Tie” Method” of Analysis of HSE Risks for your Organisation for threats that may lead to loss in terms of major accidents occurring.

• It is your expertise that will drive the workshop and achieve the goal of identifying risks and coming up with potential ways of minimising or even eliminating these risks.

• So…. let this not be a death by power point presentation but a lively interactive session with lots of interruptions and fun

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Outguess me

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Some definitions/ terms that will be used

• What is a Hazard?

• Top Event?

• Threats?

• Consequences?

• Barriers (Controls)

• Escalation Factors

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Hazard

• Hazards are shown as per the figure in the right hand side in a Yellow/ Black Box

• An example for this BowTie Workshop is “Product Storage”

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Top Event

• Release of a “Hazard” leads to a “Top Event” which is usually a loss of control event.

• For your BowTie, it is shown in the right hand side in a Red/ Yellow/ Orange Circle

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Threats

• Typical HSE Threats are:

Internal Corrosion

Overfilling

Lack of Maintenance

Asset Impact by vehicles

And so on….

These are shown on the BowTie within Blue Border boxes

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Controls or Barriers

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• Controls or Barriers are designed to neutralise the “Threats” and stop the Top Event (Loss of control) leading to a Consequence.

• Barriers may be colour coded (for example “green” for good/ effective control that does not rely on procedures alone) as shown in next slide


Barrier (Control) Effectiveness

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Control (Barrier) Effectiveness Key

Effectiveness Is it used? Is it in place?

Does it work/ is it effective/ human dependency?

Bow Tie Control Colour

Good AlwaysControls is very likely to work when required, little human involvement

OK MainlyControl is likely to work when required, active human involvement

Poor Rarely

Control is either non-existent or has a low chance of working when required, continuous human involvement, very complex. Actions are raised for all barriers where effectiveness is poor


Escalation Factors: Shown inside Yellow Box

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Consequences

• Examples of a consequence of the Hazard being related due to loss of control could be:

Pollution

Fire

Prosecution by Competent Authority

Serious Injury

• Consequences are shown inside Red Boxes

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Summary: A Completed Bow Tie looks like this

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QUESTIONS?


• Consider a car journey from home to work• Here the hazard is “driving”• Top Event is losing control of your car whilst driving• Threats can be listed as………• Consequences can be listed as ……..• What are your risk control barriers on each side – preventive and

mitigatory? ...............• Are there any escalation factors?

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Warm Up Exercise for the Bow Tie Workshop – 5 minutes to set the sceneCar Journey from home to work


Case Study/ 1Hypothetical Site Description

1. The site is a Liquid Chemicals bulk storage and blending facility located by the side of a major Estuary and has a series of 2 x 4 above ground Mild steel tanks within 2 separate concrete bunds. Each tank has a working capacity of 5000 M3 and the bunds are adequately sized to EA Containment Policy Score Card guidance. The chemicals are compatible and will not react if mixed accidentally in both the bunds.

2. Bulk chemicals are supplied and stored in these tanks via road tankers from the Humber Terminal and have a flashpoint of 30 C ( ) and are environmentally toxic ( ). These would cause severe pollution if released to the waters. They are not toxic or corrosive according to the CLP Classification criteria. These properties bring the site into the scope of COMAH 2015 as an Upper Tier installation.

3. Site drains are split into surface drains which go to the estuary via an interceptor and foul drains which go to the on-site sewage treatment plant and then into Water Authority sewers under a consent to discharge permit.

4. There is no fire fighting provision on the bulk tanks or the bunds and the site relies on Fire Rescue Service attendance. Site operates from 6 AM to 10 PM in two shift patterns Monday to Friday and no on site security presence. There is CCTV monitoring by external Party who would call out On Call Duty Manager.

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Case Study/ 2Bow Tie Construction Steps

• Various steps in conducting the Bow Tie analysis are:

1. Identify the hazard, top event, threats, barriers (controls) and consequences. (It is suggested that storage of bulk hazardous chemicals is the hazard to consider for this case study.

2. Secondly, loss of containment is the Top Event for this study.

3. Threats & consequences are identified in the next slide. What you have to discuss amongst your groups are the possible preventive barriers & escalation factors for prevention on the LHS and the recovery or mitigatory barriers & escalation factors on the RHS

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Case Study/3Threats & Consequences to consider

• Threats

1. Internal corrosion

2. Overfilling

3. Lack of Maintenance

4. Asset Impact by site vehicle

• Consequences

1. Major Accident to the Environment (MATTE)

2. Reputation loss and/ or Regulatory action

3. Claims/ increase in insurance costs

4. Serious accident to person(s)

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Completed Bow Tie (After the workshop)

This will be sent out to all attendees after the event based on the workshop findings.

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hitchhiker's guide to bow ties

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