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Ammonia Leak Caused By Plant Failure

Purpose

This Alert is issued to inform employers, self-employed persons, designers, manufacturers and suppliers of ammonia plant of a recent incident involving the failure of an oil filter.

Oil filter

Background

The failure of an oil filter on an ammonia compressor caused an ammonia leak and subsequent evacuation. One person was admitted to hospital but was released after several hours observation. The filter had been installed approximately seven months prior to the leak. The filter consisted of a filter element contained in a stainless steel sump, with an o-ring seal, and a nickel plated brass locking-ring (see figure 1). The locking-ring split, allowing the sump to come off, and oil and ammonia to escape (see figures 2 and 3).

An independent report found the cause of locking ring failure to be stress corrosion cracking which can occur in brass "...in the presence of ammonia and very small levels of contamination in surface moisture or condensation". The report also found that "The presence of ammonia in the environment and the applied stress on the filter locking-ring when it is tightened would promote the propagation of stress corrosion cracking".

Filter after failure of the locking ringRemaining filter head after locking-ring failure

Preventative Measures
In order to prevent similar failures it is recommended that the locking-ring material be changed from a copper based alloy to a material that is not susceptible to stress corrosion cracking and which meets the mechanical requirements specified by the designer.

Further Assistance
Should you require further assistance please contact your nearest WorkSafe office.

Acts and Regulations

Acts and regulations are available from Information Victoria on 1300 366 356 or order online at www.bookshop.vic.gov.au.

View the legislation at Victorian Law Today at www.legislation.vic.gov.au.

Further information


Note: This material has been prepared using the best information available to WorkSafe Victoria. Any information about legislative obligations or responsibilities included in this material is only applicable to the circumstances described in the material. You should always check the legislation referred to in this material and make your own judgement about what action you may need to take to ensure you have complied with the law. Accordingly, the Victorian WorkCover Authority extends no warranties as to the suitability of the information for your specific circumstances.