Research into the vulnerability of some IBCs has resulted in revised guidance for their use in the storage and transport of chemicals. Douglas Leech, Technical Director of the Chemical Business Association outlines the latest guidance on the use of IBCs.
Intermediate Bulk Containers (IBCs) offer a simple and effective method of storing and transporting chemicals. Over the years, they have proved to be flexible, cost-effective and have developed a relatively good record for safety. IBCs have become a commonplace sight in the process and the downstream user industries.
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Health and Safety Laboratory research has now revealed concerns about the combustibility of plastic IBCs and the potential for their contents to be released when exposed to even minor fires.
The UK’s Health and Safety Executive (HSE) commissioned research to identify the nature and extent of the risks involved. Undertaken by the Health & Safety Laboratory, the research revealed that many IBCs have plastic components that are susceptible to ignition. This can be caused by a even the briefest exposure to a small and transient ignition source, such as a match, grass fires or small ignited spillages. An IBC can fail rapidly in these circumstances.
Several IBC manufacturers have recognised the importance of this research and are re-engineering their IBCs to minimise or remove the risks involved.
As a result of these findings, the UK’s Chemical Business Association (CBA) and the Solvents Industry Association (SIA) have published industry guidance covering the safe storage of combustible liquids in IBCs. This guidance has been endorsed by the HSE.
The IBC guidance has five specific objectives and aims to:
• Increase the awareness of the dangers associated with the storage of packaged liquids – especially those in IBCs;
• Help in the assessment and reduction of risks;
• Advise on safe management practices in relation to IBCs;
• Provide guidance on the standards for design and construction of storage areas used for storing packaged liquids at ambient temperature and pressure; and,
• Advise on the need for precautions, maintenance, training and good housekeeping wherever packaged liquids are in IBCs are stored.
Flammability risks with IBCs in storage showed that IBC”s containing non-aqueous liquids typically fail rapidly when exposed to an engulfing fire. After failure, IBCs release their contents in a few tens of seconds (see photograph) increasing the fire loading dramatically.
The spreading of the liquid released can lead to rapid involvement of more packages. Where the liquids are combustible, large pools of free burning liquid may be produced and fire may spread very rapidly.
IBCs have been shown to be especially vulnerable to fire even when not directly involved as the ignition source.
Risk assessments need to take these factors into account – particularly in relation to the choice of a storage site and to the subsequent containment of potentially large spillages. When exposed to the heat of a fire, plastic IBCs can soften and fail catastrophically, resulting in the rapid release of their contents. If IBCs are stacked, this could mean their contents may overflow any bund-wall.
Beware of failing valves…
Many IBCs have plastic components in their valves, which are unable to withstand the effects of a fire. Initially, the leakage may be slow, but eventually the valve may fail completely. The fitment of metal outlet valves or metal valve guards to the valve housing which are more resistant to the effects of fire may help to protect against this eventuality. The guidance provides an assessment checklist in relation to fire risks.
Metal IBCs may also fail hydraulically or by ullage space explosion. The fitment of pressure relief valves will reduce the risk of catastrophic failure in the event of fire. Studies also show that an IBC with a metal pallet base has a greater resistance to fire and that this type of base will delay the structural failure of the IBC.
The guidance also outlines appropriate emergency procedures and equipment to be considered. Specialised advice may also be required when considering the selection and deployment of detection systems and fire fighting equipment.
The findings of all risk assessments should be communicated to all employees who must have information relevant to their roles regarding the hazards, the need to exclude sources of ignition and the actions to be taken in the event of an emergency – including specific training in emergency procedures and how to deal with spillages and leaks.
Written procedures for controlling the risks from the storage of liquids should be reviewed and revised as required, and should be used as the basis for training covering:
• the types of liquids stored, their properties and hazards with emphasis on combustible and flammable liquids;
• general procedures for safe handling, use of lift trucks, racking and stacking;
• recognition of abnormal situations;
• reporting of faults and incidents, including minor leaks and spills;
• use of protective clothing;
• housekeeping;
• emergency procedures, including raising the alarm, calling the fire brigade and the use of appropriate fire-fighting equipment.
The full text of the IBC guidance can be downloaded from CBA’s website, www.chemical.org.uk or from SIA’s website, www.sia-uk.org.uk
NON-METALLIC STORAGE TANKS
The CBA and the Safety Assessment Federation (SAfed) have issued new safety guidance for the operators of non-metallic storage tanks installed before 2007. It aims to ensure that operators using existing plastic tanks or vessels do not jeopardise their integrity by continuing to use them beyond a reasonable life span in relation to the substance being stored. The Guidance provides a step-by-step approach to risk assessments for existing non metallic tanks where no manufacturers’ data or documentation exists. A key focus for the new Guidance is the derivation of a proxy ‘design life’ for a non-metallic tank or vessel to take account of all aspects of its usage, including the substance being stored, the number of inlets and outlets required, fill and discharge cycles, and the temperature range of its operation. The guidance can be used in conjunction with HSE guidance PM 75 and PM87 to bridge the gaps in those documents.
The Guidance can be downloaded from CBA’s website at www.chemical.org.uk or the SAfed website at www.safed.co.uk
