JOINT CBA AND SIA GUIDANCE FOR THE STORAGE OF FLAMMABLE LIQUIDS IN SEALED PACKAGES IN SPECIFIED EXTERNAL STORAGE AREAS

Transcription

1 JOINT CBA AND SIA GUIDANCE FOR THE STORAGE OF FLAMMABLE LIQUIDS IN SEALED PACKAGES IN SPECIFIED EXTERNAL STORAGE AREAS 1

2 JOINT CBA AND SIA GUIDANCE FOR THE STORAGE OF FLAMMABLE LIQUIDS IN SEALED PACKAGES IN SPECIFIED EXTERNAL STORAGE AREAS This document recognises the HSE guidance Document HSG51 on the Storage of Flammable Liquids in Containers and provides additional industry guidance (Note: Best practice would be to provide fully protected FLTs) for the storage of such products in specified risk assessed external storage areas for distribution purposes only along the supply chain. In particular it considers the selection of Fork Lift Trucks (or Material Handling Equipment) for storage areas and includes a Generic Risk Assessment relating to the fire and explosion hazards that may arise from their use. (Note: It is important at this stage to establish the limitations of the risk assessment i.e. It does not cover the more general control measures that are discussed in HSG51 or the physical hazards such as traffic accidents arising from material handling equipment). General advice in HSG51 recommends that drum storage areas for flammable liquids are normally classified as Zone 2 hazardous areas [See Appendix 3 in HSG51 for definition of hazardous areas]. However, it is incumbent on site operators, under Regulations 5 and 7 of the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) to carry out their own specific site risk assessment and to determine the extent and types of hazardous areas that may exist on their premises. This guidance provides advice on the factors that need to be taken into account in determining hazardous areas. It also considers the engineering and management controls that can be used to reduce the occurrence and duration of any potentially explosive atmospheres to such a low level that specific stores may be classified as non-hazardous. Where these control measures are applied and the site operator concludes that there are no hazardous areas present he will need to ensure that the measures are consistently adhered to and if there are any changes in the circumstances at the site that he carries out a further risk assessment. Scope Specified external storage areas for flammable liquids, which are open to the atmosphere and which comply with standard health & safety and environmental guidance documents (i.e. HSG51). These will require, for example, secure perimeters, dedicated self-bunded containment for the storage area, separation to buildings, site boundaries etc. and either effluent treatment or interceptors for the overall site. It specifically excludes enclosed storage areas, buildings typically described as Dutch Barns or any roofed storage area. The range of products covered by this guidance includes highly flammable liquids (Packing Group II) and flammable liquids (Packing Group III) in packages to the following specifications. Boiling point range: 35 C to 200 C Flash point range: -30 C to +61 C Auto ignition Temperature: above 200 C Lower Explosion Limit: 0.6 to 2.5% Upper Explosion Limit: 2 to 13% 2

3 Flammable liquids are included as they can, if required, be kept along side highly flammable liquids in storage areas covered by the scope of this guidance. Where only flammable liquids are stored it is unlikely that circumstances will give rise to any hazardous areas but the facility should never the less be subject to its own site-specific risk assessment. Extremely flammable liquids are not included in the scope as their increased volatility means that any spills or releases will give rise to explosive atmospheres of significant size and duration and would give rise to hazardous areas. Measures to Control the Formation of Explosive Atmospheres Containment and Packages All packages should be UN tested, compatible with the products carried, sealed and integrally sound. Where plastic inner receptacle metal outer case IBC's are used for solvents the Solvent Industry Association Guidance on their use should be followed and to ensure greater protection the type fully enclosed in sheet steel to be used as opposed to the type constructed with steel tubing. The IBC s should also have a metal pallet base, the steel sheeting provides two roles that of reducing charge formation on the plastic of the container and that of providing some physical protection. The steel pallet also aids physical protection. Ventilation Storage areas should be designed to maximise natural ventilation. They should be unenclosed areas outside. Enclosed storage areas, such as buildings typically described as Dutch Barns or any roofed storage areas, will have reduced ventilation and will give rise to hazardous areas. Viscosity of flammable materials can significantly affect the risk. In the case of resins dissolved in flammable solvents the quantity of liquid evaporating can be self limiting and due to retention of the solvent in the resin mass and by the resin skinning it is unlikely for the LEL to be reached. An appropriate risk assessment should be done for this type of product. In this case it is possible internal storage with appropriate ventilation could be zoned as Non-hazardous Design of Storage Areas The ratio of storage area as a percentage of the available specified area should not exceed 80% to ensure provision of safe access and egress for Materials Handling Equipment (MHE) and personnel. The layout of the storage area should allow for ease of inspection so that any defective drums can be readily identified. Where a ratio in excess of 80% is likely to be exceeded on a regular or permanent basis, the zoning status of the specified area will require a further risk assessment, and the reclassification to a minimum Zone 2 level for the duration of the time in excess of the 80% ratio. Stacks heights should be limited for the particular packing group of any materials in the store. In practical terms this means IBC s and drums one layer high on the pallet limited to stacking two pallet layers high and for drums on the roll four high. The storage area should be designed so that metal containers are not standing in pools of rainwater for long periods allowing them to rust and deteriorate. 3

4 Operations The design and operation of the specified storage area should comply with the requirements of Workplace Transport Safety Guidance HSG136 and any supporting guidance documents. Drivers of forklift trucks should be experienced for the work they have to carry out and be provided with sufficient training and supervision so as to minimise accidents that could lead to the release of stored materials. Material handling equipment and attachments should be selected to minimise damage to containers during handling operations. For example proprietary drum clamping and lifting attachments are less likely to pierce a drum than the bare sharp forks of the truck. Housekeeping procedures should be established to minimise damage to drums from stones or other sharp objects in the store or from nails in damaged pallets. Where drums are stored and moved on pallets consideration should be given to banding the drums together in order to minimise the likelihood of individual drums falling off and being damaged. Operations under this guidance should include in the procedures a provision for daily visual inspection of the specified storage area and its contents, and in particular, checks for any visible signs of leaking packages or damaged receptacles. Operators must not undertake the dispensing, mixing, sampling or packing of flammable liquids within the specified storage area as this will give rise to releases and hazardous areas. Leaking/Damaged Receptacles In the event of damaged containers or the discovery of leaking containers, the operation of unprotected materials handling equipment within the specified storage area must cease immediately. Only hand operated handling equipment or equipment protected so as to be ATEX compliant for the zone level assessed as applicable in these circumstances should be used. Operational procedures should require the elimination of risk using emergency containment measures specified in HSG51 Paragraph 179 linked for example to the use of sealing putty and/or over drums or, decanting to undamaged receptacles. The procedure should also specify what conditions must be met before operations under this guidance can recommence which should include the clean up of any residues and the elapse of a suitable time period to enable natural dispersion of any residual product or vapour. Returnable Packaging Operation procedures should specify that where a returnable packaging system is in operation for flammable liquids, they should be checked by the drivers before loading onto the vehicle for the return journey to ensure that they are notionally empty, sealed and not leaking. A further visual examination should be undertaken when offloading from the returning vehicle before being placed either into the specified full receptacle storage area or, into an alternative segregated storage area within the site. 4

5 Other Control Measures Even where site operators have concluded that storage areas are classified as nonhazardous they still have duties under DSEAR to reduce so far as is reasonably practicable the risks of fire and explosion. This will include measures to avoid ignition and heat sources such as smoking and naked flames in storage areas. They will also need to consider the fitment of additional precautionary flame and explosion proofing equipment, including engine shutdown systems, gas detection systems etc and spark proof forks, e.g. stainless steel or laminated. 5

6 Risk Assessment for FLT use in Flammable Storage Area Purpose to assess the risk arising from the specification of FLT s used in storage of flammable solvents in external storage areas. Task/Location Hazard Who might be harmed? Existing controls Storage of Flammable Solvents - outside packed storage Fire main risk, explosion a possibility HSG 51 complied with. FLT drivers trained and aware of Hazards. Outside storage allows liquids and vapours to rapidly disperse significantly lowering the risk of ignition. Release of flammable vapour from leaking drums Regular inspection for leakers. Emergency Procedures to be followed for leaking containers (These procedures must address the presence of flammable vapour and the inherent hazards and exclude unprotected FLTs) Release of flammable vapour from dropped drums UN packs. Single stacked Drums on pallets/ibc s only two pallets high or four high on the roll. Emergency Procedures to be followed for leaking containers (These procedures must address the presence of flammable vapour and the inherent hazards and exclude unprotected FLTs) Release of flammable vapour from drums damaged by FLTs Emergency Procedures to be followed for leaking containers (These procedures must address the presence of flammable vapour and the inherent hazards and exclude unprotected FLTs) Ignition due to electric spark or from hot surface on FLT Ensure LEL never present in conjunction with spark or hot surface. Diesel and Electric trucks have vapour detection equipment set at a maximum of 25% LEL. Ignition from Static on FLT Ensure FLT s earthed by use of conductive tyres and/or conductive strips to ground 6

7 Conclusion Outside flammable storage is inherently safer than internal storage due to the faster dispersal rate of vapour. The presence of flammable vapour between the explosion limits is extremely unlikely if all the storage criteria covered in this document are met. This in alliance with the use of vapour detection equipment ensures the safe handling and storage of flammable liquids externally. If the above criteria are met the storage area can be deemed non-hazardous as defined in the regulations. 7