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Explosives Inspectorate | Alert | No.107 V 1 | 11 November 2022

Electrical component failure on ammonium nitrate handling and transfer equipment

What happened?

Recent instances of corroded electrical components have resulted in a fire on a Mobile Processing Unit (MPU) and a no-flow condition of an ammonium nitrate emulsion (ANE) pump.

How did it happen?

Damaged electrical components in the vicinity of ammonium nitrate product were subject to corrosion. Routine maintenance and pre-start inspections failed to identify and replace affected wiring, solenoids, actuators and switches.

In one instance, a wiring harness with damaged insulation on a MPU bin lid actuator energized resulting in a small fire.

In another incident, an internally corroded actuator energized and started a NAPCO™ ANE  pump while the mine re-load was unattended.

Key issues

Critical hazards associated with ammonium nitrate and ANE that affect electrical components include:

Where ANE pumps are inadvertently activated, or where ANE pumps fail to shut down, no-flow events introduce heat into the ammonium nitrate emulsion, generally under confinement. This can lead to thermal decomposition of ammonium nitrate emulsion and an unplanned detonation event.5

Recommendations

Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.

We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.

References and further information

  1. Queensland Explosives Act 1999
  2. Queensland Explosives Regulation 2017
  3. Queensland Explosives Inspectorate Information Bulletin 53
  4. Australian Standard 4326 - 2008
  5. AEISG Code of Practice - Storage and Handling of UN3375
  6. AEISG Code of Practice – Mobile Processing Units

Authorised by Hermann Fasching - Chief Inspector – Explosives

Contact: Haydn Isaac, Principal Inspector of Explosives – Northern Operations , +61 7 3199 8023

Issued by Resources Safety & Health Queensland

Safety: This information is issued to promote safety through experience. It is not to be taken as a statement of law and must not be construed to waive or modify any legal obligation.

All information on this page (Electrical component failure on ammonium nitrate handling and transfer equipment - https://www.rshq.qld.gov.au/safety-notices/explosives/electrical-component-failure-on-ammonium-nitrate-handling-and-transfer-equipment) is correct as of time of printing (9 Dec 2022 6:19 am).