A Public report prepared by the HSE on behalf of the Competent Authority

• Main contents
• Power Distribution Failure - 29th May 2000
• MP Steam Main Rupture - 7th June 2000
• Fluidised Catalytic Cracker Unit (FCCU) Fire - 10th June 2000
• Background
• Events leading up to the incident
• Details of the Incident
• Emergency Response
• Competent Authority Investigation
• Key Findings - Cause and Effects
• Findings of the Competent Authority Investigation
• Competent Authority Actions and Recommendations

The incidents
Fluidised Catalytic Cracker Unit (FCCU) Fire - 10th June 2000

Competent Authority Actions and Recommendations

The Competent Authority investigation required that BP should take the following measures before re-introduction of hydrocarbon to the FCCU “light ends” section. The incident has substantial commercial implications for the site. (The Fluidised Catalytic Cracker Unit is currently not operational whilst BP are evaluating the option of re-building the facility).

FCCU Recommendations – Prior to restart

Mechanical integrity

Demonstration that the mechanical integrity of pipework on the “light ends” section of the FCCU is assured, in particular, with respect to the following:

• Stresses caused by:

  • Fabrication;
  • Assembly and erection, including misalignment and structural attachments;
  • Mechanically induced vibration cycling;
  • Temperature effects and thermal cycling;
  • Self weight and effect of supports, restraints and guides;
  • Reaction forces and other shock loading;
  • Pressure;
  • Erosion, corrosion and environmental cracking.
• Dead legs and drain points to be minimised and, where retained, assessed against the above failure modes.
• Redundant equipment and pipework, including drain/vent points, to be removed, where practicable.

BP confirmed that the recommendations would be addressed before the FCCU was started up again and would be dealt with in the design of the revamped “light ends” section.

Emergency shutdown arrangements

Demonstration that adequate arrangements have been identified for the emergency shutdown of the “light ends” section of the FCCU need to be considered (in particular the following):

• Installation of remotely operated shut-off valves (ROSOVs) to allow rapid remote isolation of significant process inventories in order to minimise the consequences of an uncontrolled leak and allow remote emergency shutdown of ancillary equipment, such as pumps.
• Safe means for emergency depressurisation of columns or vessels, where reasonably practicable.

BP confirmed that the recommendations would be addressed before the FCCU was started up again and would be dealt with in the design of the revamped “light ends” section.

Alarm flooding

Demonstration that adequate arrangements have been identified to ensure a timely and effective response by Central Control Building operators to those alarms necessary for the prevention and mitigation of major accidents, taking due account of the number, presentation and rate of presentation of alarms during plant start up, or other upset conditions, and any relevant factors set out in industry best practice guidelines (the EEMUA guidelines).

BP confirmed that the recommendations would be addressed before the FCCU was started up again and would be dealt with in the design of the revamped “light ends” section.

Further FCCU recommendations

The HSE investigation also recommended that improvements be made in the following areas of FCCU operation.

• Change control – rigorous change control procedures should be employed;
• Risk assessment – a review of the FCCU risk assessment should be undertaken which considers critical process effects on start-up, e.g. de-watering, opening FCVs, exceeding process parameters, thermal cycling, transmitted vibration etc;
• Control/instrumentation/electrical equipment;
• Management review – a high level overview of unit operations should be maintained to ensure abnormal operation of the process plant is identified and the full implications assessed;
• Communications/competency – process technicians should receive additional training and instructions to enable them to recognise situations where there may be serious implications for process plant.

Recommendations for the Complex

The HSE investigation also recommended that improvements be made in the following areas site wide.

• Pipework inspection regime – a review of the corporate inspection regime should be carried out in the light of the FCCU history and other refinery incidents;
• Redundant equipment – a policy should be put in place for redundant equipment;
• Remote isolation of process plant – BP’s philosophy on remote isolation of plant should be reviewed. The implications for other plants on the Complex should be considered;
• Project review – the corporate system for reviewing the effect of significant projects (PHSER Stage 6) should be followed;
• Process safety review – systematic reviews should be initiated at regular intervals to help assure the overall integrity of process units. They should include the following elements:
  • Operating and inspection histories;
  • The validity of previous risk assessments;
  • Hardware and software changes;
  • Significant incidents and near misses;
  • Audits;
  • Measurement against current standards and legislation;
  • Major accident hazards identified in safety reports.