Formation of Tetra-Amine Copper Nitrate (TACN) on copper fittings located on Mobile Processing Unit (MPU)

What happened?

During a routine inspection by the Explosives Inspectorate the formation of Tetra-Amine Copper Nitrate (TACN) was identified on a brass padlock and copper fittings located on an explosive Mobile Processing Unit (MPU).

How did it happen?

Lack of knowledge and awareness of the potential for the formation of TACN on copper fittings exposed to ammonium nitrate.

Key issues

TACN is an impact sensitive explosive compound formed when reactive metals such as zinc, copper or its alloys (brass) are exposed to an aqueous solution of ammonium nitrate.

The impact required to initiate TACN is reported to be equivalent to dropping a 2 kg weight from a height of approximately 20 cm.

Persons working on equipment contaminated with TACN can be exposed to the potential for a small, localised explosion caused by impact or heat to the TACN affected areas.

Recommendations

Operators who store, transport, use and manufacture ammonium nitrate should:

replace reactive metal fittings on MPU with non-reactive materials wherever possible.
replace all reactive metals in ammonium nitrate and emulsion storage and handling facilities with non-reactive materials (e.g., stainless steel, aluminium, or plastic where climatically suitable).
ensure engineering standards include the above recommendations.
review workshop procedures to ensure that they highlight the hazards associated with the use of reactive metals on vehicles and storage areas exposed to ammonium nitrate.
train employees including maintenance workers to identify TACN.
refer to explosive’s technical advice on cleaning methods to remove possible TACN compound.
never use impact or hot-work tools on an item known or suspected to contain TACN.
regularly wash down areas exposed to ammonium nitrate spillages or dust.

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

Authorised by Hermann Fasching - Chief Inspector – Explosives

Contact: Paul White, Senior Inspector of Explosives , +61 7 3199 8023 explosives@rshq.qld.gov.au

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.

Security: This information is issued to promote security 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.

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