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Thermal fluid systems safety alert

23 January 2013

A health and safety issue related to the operation of thermal fluid systems has come to light.With an estimated 4,000 UK companies operating such systems, this needs urgent attention, says HTS Health & safety incident

A health and safety issue related to the operation of thermal fluid systems has come to light.With an estimated 4,000 UK companies operating such systems, this needs urgent attention, says HTS

Health & safety incidents relating to thermal fluid systems can be extremely serious in nature and are more common than many people think. The HSE recently issued a prohibition notice to a UK company following a major thermal fluid incident and significantly, following that incident, has identified thermal fluid systems as a fire and explosion hazard. There have been other serious incidents elsewhere this year including a thermal fluid-related explosion and fire at a German panel products plant which tragically caused 3 fatalities.

As specialists in thermal fluid systems for 15 years, Heat Transfer Systems believes that most companies will be aware that any system that operates above the flash point of the thermal fluid falls under the "Dangerous Substances and Explosive Atmosphere" (DSEAR) Regulations 2002.

However, many people are unaware that all heat transfer fluids degrade over time. This degradation can cause the fluid's flash point to decrease dramatically, so that thermal fluids which were not flammable at the operating temperature when they were initially installed may, over time, become flammable at the operating conditions.

The DSEAR regulations require that the risk from dangerous substances (flammable materials) is assessed and eliminated or reduced. Systems need to be put in place to reduce the risk and manage the residual risk. The ATEX directives require the hazardous areas to be identified.

Regular thermal fluid testing and the results obtained will indicate the physical condition of the fluid and the degree of risk in the event of a fluid release. However, flash point testing alone is not enough to comply with DSEAR. Procedures are also needed to change out the thermal fluid, or remove the lower flash point components from the thermal fluid. HTS is concerned that the majority of companies operating thermal fluid systems may not be aware of this.

From HTS' experience of systems both in the UK and across Europe, many thermal fluid systems will have Zone 2 hazardous areas as defined under the "ATEX Directive" (1999/92/EC). As such, area classification is required to determine the location and extent of the hazardous areas, together with a full risk assessment to identify the fire or explosion hazards and any actions required to reduce the risk, which must include specialist training for relevant employees. As Alison McKay of PROjEN explained, "Hazardous areas can be present not just where a fluid is handled above its flash point. If the thermal fluid is handled under pressure a mist or spray can be formed, which can form an explosive atmosphere at temperatures below the flash point".

PROjEN has been working with HTS to designate the hazardous areas in thermal fluid systems. PROjEN has considerable experience in determining hazardous areas for a wide range of processes, including systems handling natural gas, using the recognised standards (BS EN 60079-10-1 and IP15). PROjEN also has extensive experience of carrying out DSEAR Risk Assessments to determine the level of fire or explosion risk and making recommendations to reduce the risk.

Using the DSEAR risk assessment, elimination and mitigation methodologies will give owners greater comfort that they are operating their systems as safely as possible and will have the added benefit of being a qualitative approach that demonstrates good risk management to their insurers.

Richard Franklin of HTS believes that historically, there has been little regulation regarding the majority of manufacturing installations using thermal fluids: "Most systems operate in liquid phase with a pressurisation of below 0.5 bar (g) and as such are exempt from inspection under the Pressure Equipment Directive (97/23/EC). The majority of European installations have used a German standard under DIN 4754 (1994- 09) - Heat transfer systems operating with organic heat transfer media - Safety requirements and testing. At the same time, most thermal fluid heaters are excluded from the ATEX directive as appliances that burn gaseous fuels and are regulated under 90/396/EEC.

Of greatest significance is that the process and pipeline systems that these heaters service are not exempt. This means that the majority of system users are not aware of their responsibilities under ATEX. Also, many system designers and suppliers across Europe are not aware of their responsibilities, and we believe could be handing over systems following commissioning without the required risk assessments, training and documentation.

"As compliance was required by the 1st July 2006 the industry needs to play catch up. It is a great shame that it has taken a number of incidents to bring the industry safety shortfall to the attention of operators, engineers, insurance companies as well as the HSE."