Safety alert 12/2009 - Bulk dry powder discharge tanker

This publication is for: 
Employee / workerEmployer

During the unloading of a bulk dry powder discharge tanker, the tank (a pressure vessel) failed, causing the death of two workers.  The tank was connected to a large portable compressor supplying compressed air to discharge the load, which was a mineral powder (barite).

Inspections revealed that the tanker had not been inspected by a competent person for some years, and had several repairs that were below acceptable pressure vessel standards.  

While under pressure, the tank had a catastrophic failure.  

Factors to consider

  • The pressure vessel and its repairs were not inspected by a competent person.
  • The air supply was not correctly regulated.
  • The shell of the tank could not withstand the pressure imposed by the compressed air. 


  • Follow the designer’s and/or manufacturer’s instructions for safe tanker operation.
  • Supplied air pressure must be displayed by a calibrated pressure gauge, should and not exceed the designer’s and/or manufacturer’s instructions.
  • Provide safety devices of the correct size to relieve excess pressure, without accumulation and set at or below the design pressure of the pressure vessel. 
  • Pressure vessels must be inspected periodically, in accordance with AS/NZS 3788 Pressure equipment In-service Inspection.
  • Pressure vessel repairs and/or alterations must be inspected by a competent person. 
  • Dry bulk powder discharge tankers are a category of pressure equipment which requires a current registration with WorkSafe or another regulatory authority responsible for plant safety.

Further information

  • AS/NZS 3788 Pressure Equipment In-service Inspection
  • AS 4458 Pressure Equipment - Manufacture

Further information can be obtained from WorkSafe’s website or by contacting customer service on 1300 307 877 or email

This Alert contains safety information following inquires made by WorkSafe about an incident or unsafe practice. The information contained in this Alert does not necessarily include the outcome of WorkSafe’s action with respect to an incident.  WorkSafe does not warrant the information in this Alert is complete or up to date and does not accept any liability to any person for the information in this report or as to its use.

Last updated 29 Jun 2017

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