Safety warning after ICL blast verdict

London -- ICL Plastics Ltd and its associate company ICL Tech Ltd have each been fined £200,000 at a High Court hearing in Glasgow  for breaching health and safety regulations relating to the explosion and building collapse at the ICL site in Maryhill, Glasgow on 11 May 2004.  

The blast, which killed nine people and seriously injured 40 others, was caused by a leak from a corroded pipe carrying liquefied petroleum gas (LPG), which then accumulated in an unventilated room, according to  Stewart Campbell, HSE director Scotland.

“It is important for all those affected by the explosion that lessons are learned and I would like to remind all users and suppliers of LPG of the risk from buried pipes carrying LPG, particularly when located near areas where gas can accumulate,” said Campbell.

“The dangers posed by buried pipes can be overcome by a systematic approach to risk management and the findings of the investigation reinforce the need for effective arrangements for the maintenance, renewal or repositioning of buried pipes,” he added.

HSE is strongly advising that buried metallic pipes are effectively corrosion protected and maintained, or replaced either with over ground pipes or buried plastic pipes constructed and installed to the appropriate standards.

HSE Summary of Incident:

Grovepark Mills was originally built in 1878 as a weaving mill. ICL Plastics occupied the premises in 1968. At the time of the incident there were 3 buildings on site; the main building (the site of the accident), the fabrication building and the Stockline Plastics building.

The main mill building consisted of a basement, ground and three additional floors. The main production areas – a coating shop and despatch area - were on the ground floor, and the office accommodation was on the second floor.

The basement, which was beneath the despatch area, had a ceiling, which comprised of a steel structure with concrete slab infill. The main access to the building was via a yard on the south side of the building off Grovepark Place. In the south corner of the yard was an LPG tank.

Investigators found evidence of a gas or dust explosion near the underside of a steel structure that formed the ceiling of the basement. These forces damaged the I-section steel frame, welds and checker plate.

From analysis of the mechanical damage to the steel structure, the explosion overpressure produced in the basement is at least 692 mbar. The overpressure produced during the explosion violently lifted and broke apart the dispatch floor/ground floor.

This happened in a number of stages as the explosion developed over several seconds. Initially it appears to have lifted the steel structure breaking it apart from its supporting legs. The welds holding the checker plate covering in place then failed. At some stage the concrete floor section also broke apart.

These events resulted in the explosion venting into the ground floor space above the basement causing the collapse of the building as the force of the explosion pushed the walls outward, allowing the floor supports to fall.

A number of potential sources for the explosive atmosphere were identified which include LPG, natural gas and possibly organic dusts or solvents. However, the evidence indicated that of these the only credible source of the explosive atmosphere was a leak from a failed underground LPG pipe. The pipe was not installed nor maintained to an acceptable standard.

The failure in the LPG pipe was adjacent to the basement wall, and tracer gas testing showed the availability of a leakage path from the failure to the inside of the basement. An investigation of the potential for the occurrence of flammable gases in the ground at the ICL site revealed a plume of propane in the ground consistent with leakage from the LPG supply pipe.

From the evidence available the explosion did not involve mains natural gas, process dust or solvent, as they were not present in the basement nor the ground floor dispatch area above the basement. There is no credible mechanism for flammable atmospheres of natural gas, dust or solvents to have entered the basement.