Preventing losses: Fire Resistant Anti Static (FRAS) Conveyor Belts

Major mining losses from the last few years have shown that conveyor fires can cause significant damage and have a large impact to clients' supply chains. These losses are significant and over the past seven years the industry has seen individual losses as high as USD$125m1.  Sites must prioritize the protection of critical conveyors as only a short outage can generate very large Business Interruption impacts.

Fire Resistant Anti Static (FRAS) conveyors belts can help reduce this risk but it is not the only means of protection.

Hazards when working with conveyor belts

  • Fire: Conveyors are designed to transport material meaning they can also transport a flame. As smoke detection can have a slower response time when air velocity is increased, a fire can be transported a considerable distance by a conveyor belt before being detected. Intervention time is key to controlling conveyor fires as high heat can lead to structural collapse.
  • Toxic smoke: Burning rubber from an ignited conveyor belt can produce large amounts of black toxic smoke which can be particularly hazardous  in underground environments, making it difficult for people to evacuate the mine and for rescue efforts.
  • Business interruption: Loss of a critical conveyor can have a large impact on business due to the replacement time to rebuild structures.

What are Fire Resistant Anti Static (FRAS) conveyors belts?

Fire Resistant Anti Static (FRAS) conveyor belts are engineered so that the top and bottom covers of the conveyor belt meet local fire retardancy standards. This means these belts are difficult to ignite and should never be the cause of a fire. Additionally, if ignited by an external fire source, they should minimize the propagation of the fire. These conveyor belts are also Anti Static, meaning they provide electrical resistance to avoid the build-up of static electricity.

FRAS conveyors belts allow more time for an existing protection system (fire detection / fire sprinklers) to respond. Flame spread can be reduced therefore increasing the effectiveness of the protection system. While FRAS belting can reduce fire exposure, it should not be relied on as the sole means of fire protection.

Loss prevention and mitigation measures to avoid the risk of a potential conveyor belt fire

Eliminate and control potential ignition sources

  • Restrict hot work and smoking. When this activity is absolutely necessary, use a formal hot work permit system.
  • Mechanical failure of drives, pulleys, scrapers, belt alignment and tracking can lead to localised heating and ignition. Using the correct process control interlocks, having strong preventative maintenance plans and regular visual inspections are important.

Select the right conveyor belts

Consider can FRAS conveyor belts be used over traditional belts to add more protection to your operation?

  • There are many FRAS standards available with the widely accepted European Norms (EN) referred to in this paper. These standards along with your local standard can be used to determine the correct FRAS belt grade required for your application.
  • When considering the use of FRAS conveyor belting and grade, pay attention to the location of the belt (above ground / underground), material conveyed and conveyor structure. Control interlocks should be in place and fire protection installed to reduce the inherent risk to an acceptable level.
  • When selecting the right FRAS conveyor belts for your operations consider the following:

Is your material conveyed abrasive?

Consider the need for a thicker rubber skim. Belt covers wear as do fire resistant covers.

Do you have the required mechanical protection in place to avoid slippage, friction & misalignment?

Consider selecting a higher grade of FRAS belt to add more protection and ensure it is regularly checked and tested.

Is the conveyor difficult to access – below ground or enclosed – and as such require additional protection?

Consider a higher grade of FRAS conveyor should be considered as access for manual fire intervention can be difficult.

Is the conveyor belt a production bottleneck and if lost could cause a material business impact?

The use of FRAS belting in conjunction with appropriate controls and fire protection can offer another layer of protection.

  • If retrofitting an existing conveyor structure with FRAS, take into consideration the change in properties of the belt to ensure the structure is fit for purpose.

Maintain Fire Resistant Anti Static (FRAS) conveyer belts

  • As FRAS belts can wear faster and resistance to fire decreases with wear, abrasion resistance is an important consideration when selecting a belt.
  • Sites need to ensure maintenance plans are consistent with the wear properties of the belt to ensure the FRAS properties are maintained for which it was installed.

Test your conveyor belts before use

  • Standards and testing requirements on manufacturers can vary. Be diligent and test your conveyor belt through an independent laboratory to ensure it meets your own requirements and specification before use.
  • The basis of most tests used in normal industrial application is EN/ISO340 and includes the:

Gallery Test

Designed to replicate an enclosed conveyor.

Drum Friction Test

Designed to show how friction can ignite a belt.

Laboratory Flame Test

Designed to see if a mass of conveyor belt is ignited with a small ignition source.

Electrical Resistance Test

Designed to test build up and discharge of static electrical charge on a moving conveyor.

  • Use an accredited laboratory to test your conveyor belts to ensure they meet your local regulations.

Maintain good housekeeping measures

  • Conveyor spillage should be reduced and daily belt walks should be used to address poor housekeeping and to prevent against rapid deterioration of the building structure or contents.
  • Moving parts should be regularly inspected for changes in vibration and temperature. Remote monitoring should be considered.

It is recommended all sites should conduct a risk assessment on their conveyor infrastructure and determine the necessary controls to put in place. The risk assessment should assess risk not only to people but also infrastructure. Controls should lower the residual risk to acceptable levels in accordance with company guidance and regulation.

Learn more about our Risk Engineering Services.
 

1 Major mining losses 2013-19 from Willis Towers Watson, WTW-Mining-Risk-Review-2019.

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