Key points
An estimated 3,000 companies within the UK’s process industries operate thermal fluid systems to transfer heat around their manufacturing plants. ATEX and DSEAR legislation stipulate that these firms must proactively monitor and manage the condition of their systems in order to protect employees from the risk of fire or explosion.
In this feature, Richard Franklin, managing director of UK Thermal Fluid Solutions (TFS), offers some tips to Process Industry Informer readers on how best to monitor the condition of their thermal fluid systems. He stresses the way in which the implementation of a continuous risk assessment and management programme can help firms to save money as well as lives.
1. Regularly monitor the condition of thermal fluid
The heat transfer media used in thermal fluid systems are typically mineral or synthetic oils. A system’s operating temperature is invariably higher than the “closed cup flash point” of the media – the minimum temperature at which, in the presence of a source of ignition, such as light switches, pump failure or sparks, the fluid’s vapours will ignite.
Where heat transfer systems operate under high pressure, any leaks from the pipework at points such as flanged joints, valves and connection points, can create mists or sprays, which result in the creation of an explosive atmosphere outside the system.
Most thermal fluids operate above their flash points, and the systems that contain them must therefore be treated on a risk assessment basis.
Whether inside or outside heat transfer systems, on ignition, volatile atmospheres result in fires and explosions, and European ATEX (Atmosphère Explosible) legislation – implemented in the UK via DSEAR (Dangerous Substances and Explosive Atmospheres Regulations) – stipulates requirements for the protection of workers against such incidents arising from the presence of hazardous substances in the workplace.
PUWER (Provision and Use of Work Equipment Regulations) stipulates that all installations, including thermal fluid systems, are operated correctly and properly maintained.
While most companies are aware that heat transfer systems operating above the flash point of the fluid must be maintained according to DSEAR, many do not appreciate that organic thermal fluids based on mineral oils will degrade over time.
Degradation can cause a fluid’s flash point to decrease, as “light” materials with lower flash point than the heat transfer fluid itself are generated, reducing the flash point of the fluid overall, so that fluids that were not flammable at the operating temperature at installation, eventually become flammable.
DSEAR demands that the risks inherent in the use of flammable fluids are assessed and eliminated or reduced. Regular fluid sampling and analysis is required to indicate when unacceptably low flash points are reached. If necessary, oil must be replaced or conditioned so that a safe flash point is restored.
The formation of explosive atmospheres outside the thermal fluid system following a leak can be reduced via the fitting of spray-protected safe rings.
The importance of adherence to DSEAR cannot be overstated. Although thermal oil fires and explosions are not common, they do occur with avoidable regularity.
Over a ten year period clients of insurer FM Global experienced 54 fires and explosions caused by thermal oil. In February, 2010, the thermal oil boiler at a wood processing plant in Northern Europe exploded, killing three people.
2. Use long-lasting thermal fluids
Employing a thermal fluid with a high flash point combined with chemical stability, prolongs the period for which it may be safely used, making it highly cost-efficient.
Such fluids enable companies to operate their systems safely and efficiently at high temperatures long-term, reducing the frequency with which the oil needs to be reconditioned or replaced in order to ensure that vital parameters such as minimum flash points are always maintained.
Following six months of testing at our Derbyshire headquarters, this summer the firm launched Magma Ultima and its food grade sister, Thermaltrans FGS, two semi-synthetic heat transfer fluids with the market’s highest ever flash point of over 2600.
The chemical composition of these highly refined oils ensures a considerable level of stability allowing the fluids to resist for longer the process of degradation and consequent flash point reduction.
The fluids’ exceptional stability means that they may safely be used in systems operating at a bulk (highest average) temperature of up to 3000C and film (container boundary) temperature of up to 3250C.
3. Recondition rather than replace thermal fluid
Historically, the only available option for firms whose thermal fluids required flash point restoration was total replacement, but some suppliers are now able to recondition customers’ existing oils in order to maintain the appropriate flash points.
The first to offer this service, which offers a quick, cost-effective, environmentally sustainable alternative to total fluid replacement, HTfluidfit rigs remove volatile organic compounds (VOCs) from the oil, returning it to a safe condition, extending fluid life by a factor of at least 10, saving customers up to 70% of their thermal fluid costs.
4. Employ a long-term risk management strategy
Only a continuous risk assessment and management approach to thermal fluid system condition monitoring will ensure a system’s safe and efficient operation and ATEX, DSEAR and PUWER compliance at all times.
While the development of bespoke, comprehensive, continuous improvement plans enable companies to meet DSEAR standards, the explosion protection documents that form part of our plans also enable clients to prove their safety credentials to insurers and so reduce their premiums.
Our experience within the process industries is across a range of sectors, including food, wood panel, petrochemicals and fine chemicals to achieve and maintain legislative compliance for 20 years, minimising and managing their risk, such as Premier Foods, Dow Chemical Company and Pfizer.
As well as the supply of oils and HTFluidfit, together with other providers, we offer individual services include fluid testing, analysis and advice; water removal; drainage and refill as well as a comprehensive, continuous risk management service, ensuring the safe and efficient operation of customers’ thermal fluid systems and legislative compliance, via the creation of bespoke improvement plans.
