Slurry pump explosion | Resources Safety & Health Queensland
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Mines safety alert no. 346 | 04 August 2017 | Version 1

Slurry pump explosion

What happened?

A 10/8 slurry pump exploded after becoming deadheaded during operation. The explosion propelled the associated suction pipe work several metres together with the cover plate causing significant damage to surrounding structures. There was no worker in the vicinity at the time.

How did it happen?

The investigation identified that a modification to the PLC code incorrectly allowed the pump to continue running outside its designated automatic start/stop sequence with the suction and discharge valves closed. This allowed the slurry inside the pump to become superheated and resulted in the pump explosion. The failure occurred on the pump casing bolts, allowing the impeller and pump casing to remain largely intact.
The modification to the PLC took place five years ago and bridged out the interlock that would have prevented the pump from running with the suction and discharge valves closed.
No change management process had been applied when the bridge was installed.

Recommendations

  • Change management processes should occur whenever a proposed modification to a process may have an impact on the safety and health of workers. The modification should be authorised at an appropriate level of authority, and be documented and understood by operators.
  • Where critical controls are in place to prevent catastrophic events, a regular check should be carried out to verify that the control is effective.
  • Operators should have a basic understanding of the process and of the safety critical controls that are in place.

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.

Comments

This event was able to occur because the engineering control had been bridged out.
The correct sequence of operation is almost entirely dependent on engineering controls because there is no full time monitoring of the circuit by an operator. However the incorrect operating sequence might be noticed by operators if they have a basic understanding of the filter plant circuit and the associated critical controls.

Authorised by Trevor Brown - District Inspector of Mines

Contact: Richard Horsburgh, Authorised Officer , +61 7 4028 5623

Issued by Queensland Department of Natural Resources and Mines

Placement: Place this announcement on noticeboards and ensure all relevant people in your organisation receive a copy.

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Acknowledgement of Country

RSHQ respectfully acknowledges all Aboriginal peoples and Torres Strait Islander peoples as the Traditional Owners and Custodians of the country on which we live and work. We acknowledge their continuing connection to land, waters and culture and commit to ongoing reconciliation. We pay our respect to their Elders past and present.