British Sugar stirred by the challenges of ATEX/DSEAR
25 Mar 2008
British Sugar plc operates four sugar beet processing plants in the UK producing more than one million tonnes of sugar a year — around half the UK's sugar demand. Reflecting the potential for sugar dust to create explosions, the company has long been proactive in the area of factory safety, operating in compliance with the Health and Safety at Work Act and associated legislation to ensure a safe working environment.
Well before the arrival of ATEX/DSEAR legislation, each British Sugar site produced detailed, site-specific risk assessments of all product handling, screening and storage plant, including the buildings within which the equipment was stored. These covered general zone classification, plant identification, a Basis of Safety review for each plant item, the existing equipment explosion protection measures and devices. Likewise, arrangements for earth bonding, maintenance schedules and records and housekeeping procedures were continually monitored and developed.
This robust and apparently comprehensive approach to explosion risk assessment prompted the question; "Would ATEX/DSEAR have a significant impact upon British Sugar?" The answer was definitely yes, according to senior technical services manager Alan Dempsey, explaining the company's programme to comply with the new regulations at a presentation during the EasyFairs Solids show, 11-12 March at the NEC.
DSEAR implementation has involved significant resources, both in terms of re-allocating responsibilities of existing staff to facilitate the changes and appointing external consultants, said Dempsey. Moreover, he added, the required investment in new equipment and risk-assessed modifications to existing equipment exceeded £3 million, as well as a major training initiative. Since July 2003, it has been illegal to purchase non-ATEX certified equipment for use in hazardous atmospheres and British Sugar had made it a contractual requirement on suppliers to meet their obligations.
However, the company has found a lack of consistent knowledge about the obligations among mechanical handling equipment suppliers. This has led British Sugar procurement teams to chair meetings between equipment suppliers and consultants to raise the knowledge level in this important area.
The aim, said Dempsey, "is to ensure that equipment to be supplied would meet the relevant requirements and/or is subject to testing and assessment by an accredited body.' Suppliers have, in British Sugar's opinion, disappointedly lagged behind the demand.
"British Sugar has had to challenge the perceptions of some suppliers of mechanical handling equipment who deny that relevant standards or ATEX-certified equipment actually exist when referred to in British Sugar specifications," said Dempsey. Some suppliers, he added, offer ATEX-certified equipment "at heavily inflated prices, far in excess of the real cost of achieving certification. This is an unfortunate reflection on the general lack of awareness of the mechanical equipment supply and demand market and will invariably take some time to reach a balance point."
British Sugar carried out a full review of legacy specifications, standards and procedures to meet the more exacting requirements of DSEAR. This, said Dempsey, has been "a highly demanding activity for a business with a developed business management system incorporating, ISO 9002, ISO 14001 and OHSAS 18001, and individual sites holding their own certifications."
Among the many early challenges posed by the compliance process, Dempsey said British Sugar struggled to find a single point of expertise with whom to engage. No one organisation offered full competence to support the implementation programme, he said.
This led British Sugar to work with five separate groups, each with its own expertise and competence in the application of DSEAR. The elements of expertise covered: zone classification, Basis of Safety reviews, application of explosion protection systems; equipment strength assessments; and existing electrical and mechanical (non- electrical) equipment assessments.
British Sugar's early zone classification attempts led to over-zoning due to it adopting a lowest risk approach. However, with support from an external expert group, the company reassessed the initial zoning classification in accordance with BS EN50281-3, allowing much more appropriate and manageable safety measures to be implemented, said Dempsey.
One zoning technique adopted was to group similar plant together into generic groups. For example, British Sugar operates over 200 sugar handling screw conveyors, which are mostly similar in construction and operation, and so could be grouped under a generic model.
"The generic model incorporates the 'worst case' parameters from the group of over 200 with regard to ignition risks, such as maximum speed and loads," explained Dempsey. "The assessment of ignition risks can be carried out on the single generic model, and if the 'worse case' is proven to be safe with existing control measures, then individual assessments of each screw conveyor are eliminated."
Another key element of DSEAR is the Basis of Safety assessment of all installed plant and new installations. This requires very formalised documentation proving that the risk control assessment process has been properly followed, including generation of drawings and maintenance and inspection procedures.
The Basis of Safety reviews on some mechanical handling plant identified chemical suppression systems and chemical anti-propagation barriers, activated by pressure-rise detection and or spark-detection, as the most effective risk minimisation tool. These were installed primarily on belt and bucket elevator systems.
The early over-zoning classification could have resulted in far greater application of these explosion protection systems, noted Dempsey. Joint research with equipment companies, consultants and external testing houses also helped to moderate capital investment by providing more pragmatic solutions to ignition source risk assessment and residual hazard controls.
Equipment strength assessment, meanwhile, proved "at times controversial" due to differences between the consultant's calculations and the practical measurements from the manufacturer, said Dempsey. British Sugar, he added, generally adopted the consultant's calculations, which in some cases resulted in additional costs.
British Sugar's non-electrical equipment operating in hazard atmospheres also required thorough assessment and a major resource spend, noted Dempsey. This involved several thousand items of equipment in zoned areas, each requiring a Basis of Safety that provides an appropriate level of safety protection. Overall, Dempsey said that in most cases British Sugar, with expert support, has been able to understand where risks exist and where they do not, and target corrective actions. The new BS EN 13463 series ignition protection standards supported the assessment of existing ignition control measures — with 13463-5 relating to constructional safety proving a particularly effective guidance document on safety requirements for equipment with moving parts.
There are, however, still some areas in which British Sugar needs to build knowledge to improve effective determination of the existence of a genuine hazard, continued Dempsey. These, he said, include frictional heating from slippage of conveyor or power transmission belts, rubbing of metal surfaces and potential heating from bearing failure.
Well before the arrival of ATEX/DSEAR legislation, each British Sugar site produced detailed, site-specific risk assessments of all product handling, screening and storage plant, including the buildings within which the equipment was stored. These covered general zone classification, plant identification, a Basis of Safety review for each plant item, the existing equipment explosion protection measures and devices. Likewise, arrangements for earth bonding, maintenance schedules and records and housekeeping procedures were continually monitored and developed.
This robust and apparently comprehensive approach to explosion risk assessment prompted the question; "Would ATEX/DSEAR have a significant impact upon British Sugar?" The answer was definitely yes, according to senior technical services manager Alan Dempsey, explaining the company's programme to comply with the new regulations at a presentation during the EasyFairs Solids show, 11-12 March at the NEC.
DSEAR implementation has involved significant resources, both in terms of re-allocating responsibilities of existing staff to facilitate the changes and appointing external consultants, said Dempsey. Moreover, he added, the required investment in new equipment and risk-assessed modifications to existing equipment exceeded £3 million, as well as a major training initiative. Since July 2003, it has been illegal to purchase non-ATEX certified equipment for use in hazardous atmospheres and British Sugar had made it a contractual requirement on suppliers to meet their obligations.
However, the company has found a lack of consistent knowledge about the obligations among mechanical handling equipment suppliers. This has led British Sugar procurement teams to chair meetings between equipment suppliers and consultants to raise the knowledge level in this important area.
The aim, said Dempsey, "is to ensure that equipment to be supplied would meet the relevant requirements and/or is subject to testing and assessment by an accredited body.' Suppliers have, in British Sugar's opinion, disappointedly lagged behind the demand.
"British Sugar has had to challenge the perceptions of some suppliers of mechanical handling equipment who deny that relevant standards or ATEX-certified equipment actually exist when referred to in British Sugar specifications," said Dempsey. Some suppliers, he added, offer ATEX-certified equipment "at heavily inflated prices, far in excess of the real cost of achieving certification. This is an unfortunate reflection on the general lack of awareness of the mechanical equipment supply and demand market and will invariably take some time to reach a balance point."
British Sugar carried out a full review of legacy specifications, standards and procedures to meet the more exacting requirements of DSEAR. This, said Dempsey, has been "a highly demanding activity for a business with a developed business management system incorporating, ISO 9002, ISO 14001 and OHSAS 18001, and individual sites holding their own certifications."
Among the many early challenges posed by the compliance process, Dempsey said British Sugar struggled to find a single point of expertise with whom to engage. No one organisation offered full competence to support the implementation programme, he said.
This led British Sugar to work with five separate groups, each with its own expertise and competence in the application of DSEAR. The elements of expertise covered: zone classification, Basis of Safety reviews, application of explosion protection systems; equipment strength assessments; and existing electrical and mechanical (non- electrical) equipment assessments.
British Sugar's early zone classification attempts led to over-zoning due to it adopting a lowest risk approach. However, with support from an external expert group, the company reassessed the initial zoning classification in accordance with BS EN50281-3, allowing much more appropriate and manageable safety measures to be implemented, said Dempsey.
One zoning technique adopted was to group similar plant together into generic groups. For example, British Sugar operates over 200 sugar handling screw conveyors, which are mostly similar in construction and operation, and so could be grouped under a generic model.
"The generic model incorporates the 'worst case' parameters from the group of over 200 with regard to ignition risks, such as maximum speed and loads," explained Dempsey. "The assessment of ignition risks can be carried out on the single generic model, and if the 'worse case' is proven to be safe with existing control measures, then individual assessments of each screw conveyor are eliminated."
Another key element of DSEAR is the Basis of Safety assessment of all installed plant and new installations. This requires very formalised documentation proving that the risk control assessment process has been properly followed, including generation of drawings and maintenance and inspection procedures.
The Basis of Safety reviews on some mechanical handling plant identified chemical suppression systems and chemical anti-propagation barriers, activated by pressure-rise detection and or spark-detection, as the most effective risk minimisation tool. These were installed primarily on belt and bucket elevator systems.
The early over-zoning classification could have resulted in far greater application of these explosion protection systems, noted Dempsey. Joint research with equipment companies, consultants and external testing houses also helped to moderate capital investment by providing more pragmatic solutions to ignition source risk assessment and residual hazard controls.
Equipment strength assessment, meanwhile, proved "at times controversial" due to differences between the consultant's calculations and the practical measurements from the manufacturer, said Dempsey. British Sugar, he added, generally adopted the consultant's calculations, which in some cases resulted in additional costs.
British Sugar's non-electrical equipment operating in hazard atmospheres also required thorough assessment and a major resource spend, noted Dempsey. This involved several thousand items of equipment in zoned areas, each requiring a Basis of Safety that provides an appropriate level of safety protection. Overall, Dempsey said that in most cases British Sugar, with expert support, has been able to understand where risks exist and where they do not, and target corrective actions. The new BS EN 13463 series ignition protection standards supported the assessment of existing ignition control measures — with 13463-5 relating to constructional safety proving a particularly effective guidance document on safety requirements for equipment with moving parts.
There are, however, still some areas in which British Sugar needs to build knowledge to improve effective determination of the existence of a genuine hazard, continued Dempsey. These, he said, include frictional heating from slippage of conveyor or power transmission belts, rubbing of metal surfaces and potential heating from bearing failure.
