The incident took place on Easter Monday the 16th April 2001. During the morning the SGP was operating normally and the Central Control Room (CCR) reported a quiet shift, with no alarms showing for the SGP. In the early afternoon there were only 185 people on site, rather than a normal weekday figure of about 800. Most of the staff were inside buildings preparing for the shift handover, which was due to occur at 3pm. A number of people were working in the open air.

At approximately 14.20 hrs a catastrophic failure of a section of pipework on the SGP plant occurred at an elbow just downstream of a water-into-gas injection point. The six inch diameter pipe P4363, (the overhead line carrying flammable gas under high pressure),ruptured releasing a huge cloud containing around 90% ethane/propane/butane. About 20-30 seconds later the gas cloud ignited. As a result a massive explosion and fire followed.

KEY LESSONS:

Management of Pipework Inspection
• Effective pipework inspection systems are a vital major accident prevention measure for high hazard pipework.
• Such systems should at least meet current industry good practice standard.
• Decisions on inspection intervals should be informed by suitable and sufficient information on process conditions and previous inspection findings.

Management of Change
• Effective management of change systems, which consider both plant and process modifications, are essential to prevent major accidents.
• Particular care is needed to ensure that ‘quick fix’ modifications, during the commissioning and early operation phases of new plant, are covered.

Management of Corrosion
• Systematic and thorough arrangements are necessary for the effective management of corrosion on major hazard installations.
• Such arrangements should ensure that any available information on relevant corrosion degradation mechanisms is identified and acted on.
• Adequate resource, including relevant expertise, should be applied to ensure that adequate standards are achieved and maintained.

Communication
• Effective communication is an important element of any safety management system. In the context of major hazard establishments the accurate recording and effective sharing of information and data relevant to plant corrosion is essential for major accident prevention.
• Communication systems should aim to actively involve the workforce in the prevention of major accidents as part of an adequately resourced process safety management system.

Image Credit: HSE