![Process and Plant Design for DSEAR
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Page 3 of 13
b) Substances and preparation not classified under the CHIP regulations but
creates the potential for a fire or explosion
It is important to realise that DSEAR will apply even if the substance or preparation is not
classified under the CHIP Regulations. For example, mineral oil based hydraulic fluids
may not be classified under the CHIP Regulations as the flash point is higher than 55°C.
However, any leak from a pressurised system may result in a mist of oil droplets, which
can form a flammable mixture with air at ambient conditions. In this instance, the hydraulic
fluid would need to be considered under DSEAR. Water containing hydraulic fluids have
been developed over the years to eliminate the possible fire risks associated with high
pressure mineral oil systems.
Similarly, a process may store and handle a substance at conditions above its flash point,
and hence this substance would be classified as a dangerous substance under DSEAR,
even if the material was considered to be non-flammable at ambient conditions. For
example, dodecane has a flash point of 71°C, which would then need to be classified as a
dangerous substance under DSEAR if it were stored or processed at temperatures at or
above 71°C.
c) Combustible dusts
A combustible dust is not classified under the CHIP Regulations, and the explosive
properties of any powder or dust will need to be evaluated by appropriate testing. There
are a number of factors that influence the explosive properties of combustible dusts, which
include:-
Particle size
Moisture content
Presence of inert materials or flammable gases/vapours
As an approximation, above 500 microns the dust particles are unlikely to be explosive [7],
and hence may be treated as non-hazardous. However, the process handling methods
may cause particle attrition and hence generate fines. This could be in sufficient quantities
or could accumulate so that it poses a dust explosion hazard. Therefore, in determining if
a powder or dust is explosive, consideration needs to be given to the number of samples
that are required for testing, and their most appropriate location to reflect composition
changes.
It is evident from the above that determining if a dangerous substance is present within the
workplace is not as straight forward as checking the material safety data sheets, and can
require careful thought. It may also require some testing and/or other justification to
establish if and when DSEAR applies.
If dangerous substances are present in the workplace then the relevant regulations with
respect to process design within DSEAR are as follows:-
Regulation 5 requires the employer to carry out a written risk assessment associated with
the use of any dangerous substance within the workplace. The risk assessment must
consider the following factors:-
The hazardous properties of the substance. For example flash point, lower and
upper flammability limits, autoignition temperature, etc.](https://image.slidesharecdn.com/03f6a9e7-7320-4162-bd3e-c241f8da6181-160720040740/85/Process-and-Plant-Design-for-DSEAR-3-320.jpg)
Process and Plant Design for DSEAR
- 1. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 1 of 13 Process and Plant Design for DSEAR AUTHORS Christopher Bell MIChemE ABB Engineering Services Date 6th May 2005 SYNOPSIS This paper discusses the implications of the Dangerous Substances and Explosive Atmosphere Regulations (DSEAR) for the design and modification of new or existing processes and plant. Typically process development and process route selection will be determined by the chemist. The selected process route may or may not be reviewed against the hazards of the raw materials, intermediates, finished products, and process chemistry until later in the process design when there is reduced scope to eliminate the hazard by substitution or other means. The application of inherent safety principles can be a useful technique that can be utilised in achieving compliance with DSEAR. This paper discusses the implications for the development of the process and some possible approaches, applying inherent safety, that can be applied in the process plant design to help achieve compliance with DSEAR. INTRODUCTION DSEAR implements the European Directive 1999/92/EC “Minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres”, also known as the ATEX 137 directive. This directive sets minimum requirements aimed at protecting employees, contractors, visitors and the public from hazards posed by fire and explosions that involve dangerous substances. The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 implements the EU Directive 94/9/EC, also known as the product directive. This directive applies to both mechanical and electrical equipment, and covers the supply of equipment intended for use in hazardous areas as defined by the DSEAR. The directives, through incorporation in DSEAR, which came into force on 30th June 2003, will require employers to modify their approach to process design and process route selection by assessing the risks from dangerous substances and reduce or eliminate these risks early in the development stages of the process. REQUIREMENTS UNDER DSEAR Before implementing a process to establish compliance with DSEAR, it is necessary to understand to what these Regulations apply. DSEAR is concerned with the storage, handling, and use of dangerous substances, which are defined as:-
- 2. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 2 of 13 a) A substance or preparation that has been classified under the CHIP (Chemical Hazards Information and Packaging for Supply) Regulations as being either explosive, oxidising extremely flammable, highly flammable, or flammable. b) A substance or preparation that creates the potential for a fire, explosion, or similar energetic event. c) A combustible dust, which can form an explosive mixture with air or an explosive atmosphere. a) Substances and preparations classified under the CHIP regulations The hazard criteria and definitions have been established in the CHIP Regulations (Chemicals (Hazard Information and Packaging for Supply) Regulations, and are shown below. Hazard Symbol Definition Explosive Solid, liquid, pasty or gelatinous substances, and preparations, which may react exothermically without atmospheric oxygen thereby quickly evolving gases, and which under defined test conditions detonate, quickly deflagrate, or upon heating, explode when partially confined. Oxidising Substances and preparations, which give rise to a highly exothermic reaction in contact with other substances, particularly flammable substances. Extremely Flammable Liquid substances and preparations having an extremely low flash point (below 0°C) and an atmospheric boiling point (less than or equal to 35°C), and gaseous substances and preparations, which are flammable in contact with air at ambient temperature and pressure. Highly Flammable The following substances and preparations:- a) substances and preparations, which may become hot and finally catch fire in contact with air at ambient temperature without any application of energy. b) Solid substances and preparations, which may readily catch fire after brief contact with a source of ignition and which continue to burn or to be consumed after removal of the source of ignition. c) Liquid substances and preparations having a very low flash point (below 21°C but which are not extremely flammable), or d) Substances and preparations, which in contact with water or damp air, evolve extremely flammable gases in dangerous quantities. Flammable Liquid substances and preparations having a low flash point (at or above 21°C and less than or equal to 55°C).
- 3. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 3 of 13 b) Substances and preparation not classified under the CHIP regulations but creates the potential for a fire or explosion It is important to realise that DSEAR will apply even if the substance or preparation is not classified under the CHIP Regulations. For example, mineral oil based hydraulic fluids may not be classified under the CHIP Regulations as the flash point is higher than 55°C. However, any leak from a pressurised system may result in a mist of oil droplets, which can form a flammable mixture with air at ambient conditions. In this instance, the hydraulic fluid would need to be considered under DSEAR. Water containing hydraulic fluids have been developed over the years to eliminate the possible fire risks associated with high pressure mineral oil systems. Similarly, a process may store and handle a substance at conditions above its flash point, and hence this substance would be classified as a dangerous substance under DSEAR, even if the material was considered to be non-flammable at ambient conditions. For example, dodecane has a flash point of 71°C, which would then need to be classified as a dangerous substance under DSEAR if it were stored or processed at temperatures at or above 71°C. c) Combustible dusts A combustible dust is not classified under the CHIP Regulations, and the explosive properties of any powder or dust will need to be evaluated by appropriate testing. There are a number of factors that influence the explosive properties of combustible dusts, which include:- Particle size Moisture content Presence of inert materials or flammable gases/vapours As an approximation, above 500 microns the dust particles are unlikely to be explosive [7], and hence may be treated as non-hazardous. However, the process handling methods may cause particle attrition and hence generate fines. This could be in sufficient quantities or could accumulate so that it poses a dust explosion hazard. Therefore, in determining if a powder or dust is explosive, consideration needs to be given to the number of samples that are required for testing, and their most appropriate location to reflect composition changes. It is evident from the above that determining if a dangerous substance is present within the workplace is not as straight forward as checking the material safety data sheets, and can require careful thought. It may also require some testing and/or other justification to establish if and when DSEAR applies. If dangerous substances are present in the workplace then the relevant regulations with respect to process design within DSEAR are as follows:- Regulation 5 requires the employer to carry out a written risk assessment associated with the use of any dangerous substance within the workplace. The risk assessment must consider the following factors:- The hazardous properties of the substance. For example flash point, lower and upper flammability limits, autoignition temperature, etc.
- 4. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 4 of 13 The process operations, equipment used, and the process conditions. Maintenance activities. What control and mitigation measures that are already in place, and the effect of measures that are to be taken. The possibility of an explosive atmosphere forming and its likely persistence. The likelihood that an ignition source will be present. The scale of the effects of a fire or explosion. Regulation 6 requires that the risk from dangerous substances is either eliminated or reduced so far as is reasonably practicable. It also places a requirement on the employer to avoid the presence or use of a dangerous substance at the workplace by either substituting the substance or changing the process route. Where this cannot be achieved, measures should be applied that Control the risk of a fire and explosion and Mitigate the effects of any fire or explosion. Control measures are:- Reduction of the quantity of the dangerous substances to a minimum Avoidance or minimisation of any release or leak Control of any release of a dangerous substance at the source Preventing the formation of a flammable atmosphere Collecting and containing any releases Avoidance of ignition sources Avoidance of adverse conditions Segregation of incompatible dangerous substances Mitigation measures are:- Reducing to a minimum the number of employees exposed Isolation systems or methods to avoid the propagation of fires and explosions Explosion venting Explosion suppression Containment of the explosion Provision of suitable personal protective equipment Regulation 7 requires the employer to classify the workplace where an explosive atmosphere may occur into hazardous and non hazardous areas according to the likelihood and persistence of the explosive atmosphere occurring.
- 5. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 5 of 13 This regulation also requires that the overall explosion safety of the workplace is verified by a competent person. The person’s competency must be in the field of explosion protection either by experience or by professional training. Regulation 9 requires the employer to train employees in respect of the handling and use of the dangerous substances, but also on what control and mitigation measures are in place, and how they are to be used. For example, employees should be trained in the importance of using antistatic footwear, or ensuring that explosion vents are kept clear from obstructions. RISK REDUCTION AND INHERENT SAFETY PHILOSOPHY DSEAR regulation 5 requires the employer to carry out a risk assessment where a dangerous substance is present. DSEAR recognises that the hazard is present from two different sources, namely:- Hazards associated with the substance or preparation used and its chemistry. For example a substance with a low flash point. Hazards associated with the method of storage, processing and handling of a substance or preparation. For example, a high flash point material stored above its flash point. Any risk reduction method used will aim to reduce the likelihood of the incident and its possible consequences involving a dangerous substance. The risk reduction methods can be placed in the following groups:- Inherently safer systems, where the hazard is eliminated by substitution of the material or process conditions that pose the hazard. For example, the use of water based solvents rather than organic ones. Passive safety, where the hazard is minimised by designing the process and equipment to reduce the frequency or consequence of the hazard. Passive safety does not rely on the functioning of any other device. For example fire insulation, blast bays, or designing the vessel or equipment to withstand an explosion. Active safety system, where the hazard is minimised or controlled using controls, safety interlocks and other systems that detect the initiation of the fire or explosion and activate the appropriate mitigation measures. For example, a water deluge system or an explosion suppression system. Procedural safety system, where the risk is reduced by using written instructions or operating procedures to prevent the initiation of a fire or explosion. For example, this could include the use of a hot work permit system, alternatively the provision and use of antistatic footwear. Risk control strategies that are based on inherent safety systems or passive safety systems are more reliable than other systems because they do not require the operation of other equipment or systems. DSEAR regulation 6 details risk reduction measures appropriate to the storage, handling and use of dangerous substances. The measures employed and the order of priority given
- 6. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 6 of 13 to them should follow the order of reliability of the risk reduction measure. For example, consideration should be first given to inherent risk reduction measures. If this is not possible then passive risk reduction measures should be considered before active and finally procedural measures. This is reflected in the order of priority given to the control measures stated in regulation 6. When considering risk reduction measures it is most desirable to apply inherent safety measures first. These measures are:- Substitute. Substitution of the hazardous material with a less hazardous one. Minimise. This is also referred to as intensification and involves the use of smaller quantities of material. Moderate. This involves the use of less hazardous process conditions, or physical form or state. For example, more dilute solutions or lower processing temperatures and pressures. Simplify. This refers to the elimination of complexity from the process and process plant. For example, a vessel may be designed to withstand the maximum pressure developed during an internal deflagration, and hence eliminate the need for venting or suppression and the associated ongoing maintenance and inspection costs. Any of these measures can be applied. For example, if the dangerous substance cannot be substituted then a further inherent risk reduction technique would be to minimise the inventory or quantity of the dangerous substance. This can be achieved by not only limiting the quantities stored at the workplace but also by reducing line sizes. The reduction in line size reduces or minimises the release rate of the dangerous substance. The minimisation of the dangerous substance inventory and the release of the dangerous substance are the top priority risk reduction measures under DSEAR regulation 6. In reviewing risk reduction measures and inherent safety strategies, it becomes apparent that regulation 6 of DSEAR is attempting to eliminate or reduce the risks from dangerous substances by requiring the employer to implement the inherent safety philosophies discussed above.
- 7. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 7 of 13 HOW WILL DSEAR AFFECT PROCESS DESIGN The development of a process and plant design will go through several stages as shown in the simplified figure below:- Figure 1 Stages of process development Typically, the chemistry route selection often involves the R&D chemist with little or no input from the process design engineers. At this stage there may be more than one process chemistry route that is selected for evaluation. Process method selection and evaluation will usually involve an engineering team in conjunction with the chemist to identify the preferred chemistry route, which may be based on several factors such as cost, speed to market, technical risk, and SHE. Preliminary process plant design will include process description, plant capacity, preliminary process specifications for the main plant items, preliminary plot plans or layout drawings, control philosophy, line list, etc. The detailed plant design develops the preliminary process design up to and beyond pre- commissioning of the completed plant, until the plant is handed over to the operating team. The application of inherent safety strategies in general provides the greatest benefits during the early stages of the process and plant design, where it is often easier to identify Detailed Process Plant Design Preliminary Process Design Process Method Selection & Evaluation Chemistry Route Selection
- 8. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 8 of 13 less hazardous substitutes, or processing routes and conditions. As the process design develops it is more difficult to change the basic process and chemistry. However, it should be remembered that it remains possible to apply the inherent safety strategies to both existing plant and plant modifications, which is required under regulation 6 of DSEAR. Furthermore, DSEAR requires HSE inspectors and environmental health officers to be provided with evidence that efforts have been made to identify non-hazardous or less hazardous substitutes. This will inevitably mean that the implications under DSEAR of the use of any dangerous substances should be considered early on in the process route selection as well as the process design, where it is most easily influenced. DSEAR also requires that the explosion safety of the process and design are verified by a competent person. The verification may have to be obtained from a number of sources, such as the operating company and possibly the equipment vendor. For example, if explosion safety is based on suppression, then it would not be unreasonable to expect the vendor to verify the adequacy of their own design or installation. However, the plant may be interconnected with other equipment items with differing explosion safety strategies, which may require verification by other competent persons. Whilst DSEAR does not require written verification of the explosion safety of the process plant, it is recommended that a plant verification file is compiled early on in the life cycle of the project and added to through all stages of the process and plant design, including commissioning, so that it becomes a comprehensive plant basis of safety document. PROCESS AND PROCESS DESIGN APPROACH UNDER DSEAR The risk reduction measures of eliminating, or controlling the risks, through prevention and mitigation of the effects of any fire and explosion will vary according to the dangerous substance that poses the hazard. Some typical approaches have been listed below for:- combustible dusts, gases and vapours, flammable liquids and mists These approaches illustrate some of the possible methods available to the designer. However, the list is by no means exhaustive, and other alternatives not identified here may be more appropriate to individual applications. Combustible dusts Inherent Replace the combustible dust with a non flammable dust. Alternatively, it may be possible to add a diluent inert dust such as limestone to eliminate the hazard or increase the moisture content. This is a technique often used in coal mines to prevent propagation of coal dust and fire damp explosions. Increase the particle size of the dangerous substance and minimise the amount of particle size reduction during the materials handling operations. For example use flaked product or pastilles. Change the process to a wet process
- 9. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 9 of 13 Avoid dust accumulations by eliminating ledges etc. Where this is not possible surfaces should be designed to facilitate cleaning and good housekeeping. Passive Design the process plant to withstand the maximum developed deflagration pressure Minimise the handling of the dust or powder by designing solids handling equipment that minimises dust generation and dust layers. For example, dust deposits in ductwork should be minimised by ensuring there is a sufficient air velocity. Ensure that all conductive equipment is adequately earthed. Ensure that other sources of ignition are not present, such as hot surfaces or impact sparks. Prevent dust from accumulating on surfaces where the temperature is approaching the layer ignition temperature for the powder. Provide insulation to reduce surface temperatures. Active Provide an inert gas atmosphere where the oxygen concentration is below the limiting oxygen concentration at which the powder or dust is non-explosible. Install an explosion suppression system that injects an inert powder into the equipment to minimise the explosion over-pressure. Install an explosion vent that ruptures at a burst pressure that ensures that the developed explosion over-pressure is below the equipment strength. Ensure that the vented explosion is directed to a suitable location. Install fast acting isolation or divertor valves, or explosion chokes, etc, that ensure the explosion cannot propagate to inter connected plant. Procedural Segregate incompatible materials or solids. Where the powder or dust is temperature sensitive ensure that the material does not come into contact with hot surfaces or elevated temperatures. The fire at Allied Colloids in Bradford was caused by the storage of AZDN kegs close to a steam condensate line. The heating caused the kegs to rupture and spread the AZDN powder onto the ground and adjacent materials. The AZDN reacted with a second material stored beneath the kegs that resulted in a flash fire, which subsequently spread throughout the warehouse and caused considerable environmental damage due to the fire water run off into the nearby rivers. Provide the antistatic footwear, conductive flooring and simplified work instructions and testing to ensure that personnel are adequately earthed.
- 10. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 10 of 13 Gases and vapours Inherent Replace the gas with a non-hazardous gas. Replace the gas with a less hazardous liquid or solid. For example, the replacement of chlorine gas for use in swimming pools with hypochlorites or chlorates. Alternatively, the flammable gas could be replaced with a higher flash point liquid. Passive Design the process plant to withstand the maximum developed deflagration pressure. Minimise the leakage of flammable gas by utilising all welded pipe systems or minimising the use of flanges. Ensure that the pipes and equipment are located in the open, or provide suitable ventilation e.g. louvers, to ensure that there are sufficient air changes to ensure that the atmosphere well below the lower flammability limit. The gas could be refrigerated and condensed, where possible, to below its atmospheric boiling point. This minimises the potential leak rate of the substance, when compared to pressurised liquid storage. Furthermore, the storage at atmospheric pressure minimises the possibility of spray or aerosol formation in the event of any leak. Containment such as spill collection, secondary containment and disposal or treatment system should be included. For example, the ground should slope into a secondary pit, which is enclosed and vents to a suitable discharge and disposal system, e.g. scrubber or flare system. Install deflagration/ detonation arrestors in lines. Active Provide an inert gas atmosphere where the oxygen concentration is below the minimum oxygen concentration at which the vapour is flammable. Install an explosion suppression system that injects an inert powder into the equipment to minimise the explosion over-pressure. Install an explosion vent that ruptures at a burst pressure that ensures that the developed explosion over-pressure is below the equipment strength. Ensure that the vented explosion is directed to a suitable location. Install emergency shut off valves, either remotely or manually operated depending on the layout, that ensure the quantity released can be minimised and in the event that the release ignites to form a jet fire, then the supply of fuel can be isolated. Procedural
- 11. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 11 of 13 Ensure that the temperature of hot surfaces does not approach the flammable gas autoignition temperature. Identify possible ignition sources and apply appropriate measures to control them. For example, consider the prohibition of aluminium or other light metals. Provide the antistatic footwear, conductive flooring and simplified work instructions and testing to ensure that personnel are adequately earthed. Flammable liquids or mists Inherent Replace the dangerous substance with a non hazardous material. Alternatively, it may be possible to add a diluent in sufficient quantities to render it non hazardous. Replace the flammable liquid with a less hazardous liquid. For example, replace a low flash point solvent with one of a high flash point. Change the process conditions to ensure that the dangerous substance is stored and handled at a temperature well below its flash point or where decomposition reactions are known to commence. Also, reduce the operating pressures so that the formation of mist or aerosol in the event of a leak is eliminated. For example, Seveso used steam to heat the vessel used in the manufacture of TCP (2,4,5- trichlorophenol). The reaction was known to produce dioxin above temperatures of 200°C. As a result, the plant used steam at a pressure where the saturation temperature was less than 200°C, so that it was assumed to be inherently safe. However, the plant also installed a CHP unit that enabled the steam to be superheated during times of low power demand. This effectively negated the basis of safety for the reactor and is believed to be the cause of the reactor mass being heated well above 200°C. As a result up to 2 kg of dioxin TCDD (Tetrachlorodibenzodioxin) was generated and released over the surrounding countryside. Eliminate the possible hazard of process by changing the mode of operation from batch to semi-batch or continuous. This minimises the potential hazard that may arise as a result of a thermal runaway. For example, traditionally nitroglycerine was manufactured in a batch vessel with glycerine and nitrating acids. The reaction vessel was fitted with a temperature gauge and the operator was instructed to monitor the temperature. To ensure that the operator did not fall asleep he was provided with a one-legged stool. However, when the process was redesigned it was realised that the level of mixing controlled the reaction rate. Hence, the method of manufacturing was changed, so that the reaction took place in an ejector type of reactor. The ejector minimised the inventory of the dangerous substance and dramatically reduced the reaction times. The design of the ejector also meant that if the flow of nitrating acid was reduced, then so was the flow of the glycerine in the same proportion. The new reactor design was a passive safety measure that did not rely on any instrumented protective systems. Passive Passive fire protection of the exposed equipment and structures.
- 12. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 12 of 13 Design the process plant to withstand the maximum developed deflagration pressure. Minimise the leakage of flammable liquid by utilising all welded pipe systems or minimising the use of flanges. Where flanges are present, then the possibility of mist formation can be eliminated by the use of metal flange guards. Ensure that the pipe is routed in the open, or where this is not possible, provide suitable ventilation e.g. louvers, to ensure that there are enough air changes to keep the vapour concentration well below the lower flammability limit. Minimise leakage rates by using smaller pipes. Ensure that the pipes and equipment are located in the open, or provide suitable ventilation e.g. louvers, to ensure that there are sufficient air changes to maintain the atmosphere well below the lower flammability limit. Ensure that any spillage can be contained, such as spill collection, secondary containment and disposal or treatment system should be included. Containment bunds or walls should be used to minimise the size of the possible pool fire in the event of any liquid release. For example, the ground should slope into a secondary pit, which is enclosed and vents to a suitable discharge and disposal system, and is equipped with a pump to enable any spillage to be recovered or disposed of safely. Install flame arrestors on open vent lines. Active The equipment vapour space should be inerted with a suitable gas, such as nitrogen, steam or carbon dioxide. This should maintain the oxygen concentration in the vapour space below the minimum oxygen concentration. Any inerting system that uses steam or carbon dioxide requires careful design as these materials can be a source of ignition due to the generation of static electricity on water droplets and carbon dioxide snow. Where there is a risk of a mist or aerosol explosion, install an explosion vent that ruptures at a pressure that ensures the developed explosion over-pressure is below the equipment strength. Ensure that the vented explosion is directed to a suitable location. Where there is a fire risk consider the use of sprinkler or deluge systems to control fire growth. Procedural Identify possible ignition sources and apply appropriate measures to control them. For example, consider the prohibition of aluminium or other light metals. Provide the antistatic footwear, conductive flooring and simplified work instructions and testing to ensure that personnel are adequately earthed.
- 13. Process and Plant Design for DSEAR ———————————————————————————————————————————————————————————— Page 13 of 13 Segregate incompatible materials. Where the dangerous substance is temperature sensitive, either by decomposition or secondary chemistry, ensure that the material does not come into contact with hot surfaces or elevated temperatures. CONCLUSIONS It is evident from the regulations within DSEAR that the strategy for compliance with these regulations is no longer one where the employer can achieve adequate compliance after the process and plant design is complete. DSEAR strengthens the risk assessment basis for other safety legislation such as The Management of Health and Safety at Work Regulations, COMAH, and the Fire Precautions Regulations. In addition, it requires employers to further review the measures employed with an aim to integrate more inherent safety measures into not only the early stages of the process plant development and design, but also in the review of existing facilities and synthesis route. Compliance with DSEAR will embed a more inherently safe design basis within the chemical process industries. REFERENCES 1. L138 Dangerous Substances and Explosive Atmospheres Regulations 2002 Approved Code of Practice and Guidance 2. L134 Design of plant, equipment and workplaces approved code of practice and guidance 3. Inherently Safer Chemical Processes A life cycle approach CCPS 4. BS EN 1127-1 Explosive atmospheres – Explosion prevention and protection Part 1. Basic concepts and methodology 5. HSG 143 Designing and operating safe chemical reaction processes 6. Dust Explosion prevention and protection A Practical Guide, J Barton, IChemE 7. Dust Explosion prevention and protection Part 1 – Venting 2nd Edition G Lunn IChemE