The explosion at the Dow chemical factory, King's Lynn. 27th June 1976

Accident summary

At approximately 17:10 hours on the 27th June 1976 an explosion occurred killing one man and causing extensive damage to the plant and adjacent buildings.

The explosion involved a detonation of zoalene, which is used as a poultry feed additive.

The following factors may have contributed in the circumstances leading up to the explosion:

• the batch probably contained a higher percentage of impurities than most other batches due to the presence of rewashed material, some of which may have been subjected to a number of heating cycles;
• the long holding period (greater than twenty-four hours) of the material at an elevated temperature in the dryer vessel, when this material was known to have a history of thermal instability;
• the drying vessel was not cooled which was previously carried out during the former manufacturing process. The cooling was undertaken for ease of handling rather than for material safety;
• overheating of the batch material; and
• the absence of accurate process temperature and moisture indication.

The fundamental reason for this incident was a general lack of knowledge of the destructive potential of zoalene at adiabatic conditions. Neither the management nor the operating personnel were criticised for undertaking and conducting the operations that led to the explosion.

Failings in technical measures

• The explosion occurred due to the exothermic decomposition of zoalene which was held under adiabatic conditions.
• Reaction / Product Testing: thermal stability
• The existing process was changed to incorporate the drying stage without fully assessing the implications.
• Plant Modification / Change Procedures: change procedures

References

Health and Safety Executive, 'The explosion at the Dow chemical factory, King's Lynn 27 June 1976', HMSO, ISBN 011 8830 03 1, 1976.

FP Lees, 'Loss prevention in the process industries – Hazard identification, assessment and control', Volume 3, Appendix 1, Butterworth Heinemann, ISBN 0 7506 1547 8, 1996.