Retrospective Hazard Review

Transcription

1 Managing Fire Risks, Abu Dhabi Men s College, 12 th November 2014 Retrospective Hazard Review Identifying fire hazards/risks and typical weaknesses

2 Texas City US, 2005 Baker Report Jan 2007 The passing of time without a process accident is not necessarily an indication that all is well and may contribute to a dangerous and growing sense of complacency November 16, 2014 Slide 2

3 Texas City: Holes in Barriers 1. Prevention: Change to start-up procedure Poor shift handover 2. Control: Poor response to high pressure alarm No automatic trip system 3. Mitigation: Relief discharge into local stack Vehicle engine source of ignition 4. Emergency Response: Temporary buildings located too close to plant November 16, 2014 Slide 3

4 Buncefield UK, 2005 UK HSE Good process safety management does not happen by chance and requires constant active engagement. Safety management systems should specifically focus on major hazard risks and ensure that appropriate process safety indicators are used and maintained.

5 Buncefield Reason for LOPC November 16, 2014 Slide 5

6 Regulator Reaction From the boardroom down, companies must ask themselves these questions Do we understand what could go wrong? Do we know what our systems are to prevent this from happening? Do we have information to assure us that they are working effectively?

7 The need for Retrospective Hazard Reviews Process Safety Incidents Initial Learning Phase Changes in personnel Loss of knowledge Ageing equipment Creeping change Continuous Improvement Baseline Review Revalidation Life of facility

8 Key features Carried out every 5 years on existing facilities Team of experienced operations and technical staff Flexible approach HAZOP - Initiating event led Process Hazard Review (PHR) Hazardous event led Considers real experience Assesses the robustness of barriers Identifies deviations from standards Generates a prioritised improvement plan Demonstrates continuous improvement in Process Safety November 16, 2014 Slide 8

9 Experienced team Leader Scribe Process Engineer Operator Maintenance C&I Engineer Others (optional): Plant Manager Safety Manager Machines Engineer Chemist, etc November 16, 2014 Slide 9

10 Depth of review HAZOP or PHR CAUSES FAULT TREE Prevention/Control Measures Loss of Containment Mitigation Measures EVENT TREE CONSEQUENCES HAZOP (Line by line) PHR (System by system) November 16, 2014 Slide 10

11 Review Record November 16, 2014 Slide 11

12 Quality records Column Poor practice Better practice Cause Consequence Safeguards Recommendations Vague, e.g. No flow as valve closed Intermediate consequence without severity, e.g. Overpressure of vessel Not listed in sequence, not covering all measures in hierarchy, vague e.g. Alarm and trip Use of weak actions such as consider and lack of clarity on what needs to be done Manual valve V123 on kick-back line closed following maintenance due to operator error when starting pump Pressure build-up limited by feed rate at y m3/min, up to 4x design with rupture hazard, line leakage likely. Release of flammable gas, potential for ignition causing 1 to 2 fatalities to people in area All safeguards in order as event escalates, tag numbers to clearly identify, highlight lack of independence (e.g. alarm and trip using same sensor ) Use 3 W s. i.e. what needs to be done, where it applies (e.g. using tag numbers), and why it is needed (e.g. hazard reduced).

13 Typical Recommendations Hazards not identified Lack of testing for emergency measures Critical Operating Procedures not followed Lack of design data for safety critical systems Effects of changes not properly assessed Poor reliability of safety critical instruments Changes to pressure relief/flare systems Lack of inspection for critical equipment November 16, 2014 Slide 13

14 Case Study: Oil and Gas Offshore Platform Onshore Gas Treatment facility Separation of produced water and condensate from gas Gas export into national grid Joint Venture company requirement for process safety review ABB PHR with selective use of HAZOP study Approx 110 P&ID s November 16, 2014 Slide 14

15 Results from Review 2 days preparation close out meeting 8 days of team meetings, 6 hour per day 20 process systems 8 offshore, 12 onshore 154 hazardous event scenarios 2 high risk 54 medium risk 98 low risk 86 recommendations November 16, 2014 Slide 15

16 Risk ranking of Scenarios November 16, 2014 Slide 16

17 Explosion Hazard on Condensate Tank Tank Dipping Operation Spark Hazard No flame arrestor on vent Potential ignition by lightning November 16, 2014 Slide 17 No low pressure alarm Risk of air ingress

18 HP/LP Interface Hazards LC Slug Catcher Operating 80 barg LS 600LB 150LB LO Fire Case Relief System LP Separator Design 10 barg

19 No lock on LP Separator Inlet valve November 16, 2014 Slide 19

20 Revalidation Carried out every 5 years Focus on changes since previous PHR Status of actions from previous PHR Significant changes Significant process incidents Record updated with new actions Ensures continuous improvement November 16, 2014 Slide 20

21 Links with other studies SIL Determination / LOPA Safety critical task analysis Pressure Relief Assurance Process Safety in Design Retro Hazard Review Safety Case Thorough Review Cumulative risk management Alarm Management Facility Siting Assessment

22 November 16, 2014 Slide 22