SB 107 Construction of seals

Safety Bulletin 107

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If workers remain underground in an explosive atmosphere where there is a possibility of spontaneous combustion, incendive spark or other ignition source, the Underground Mine Manager must ensure that any seal installed is, as a minimum, a type D [s. 32(1)(b) of the Coal Mine Safety and Health Regulation 2001].

Schedule 4 of the Regulation—Ventilation control devices and design criteria—stipulates that the design of the seal must make it capable of withstanding an overpressure of 345 kPa. As it is impossible to test these seals in place, their reliability is being determined by checking the properties of the construction materials and by digital modelling through 3D stress analysis.

Certain measures taken (i.e. installation of pipes, tubes and doors), designed to (a) obtain information on the atmosphere behind the seal, (b) control the inertisation process, (c) prevent water build-up and (d) increase the life of the seal, have also increased the complexity of the design. For example, a recently used seal included three hatches to control the flow of goaf gases into the return as part of the inertisation process. While the seal structure and the hatches were separately rated at 345 kPa, there were concerns that the overall construction did not achieve that rating.

Under section 172 of the Coal Mine Safety and Health Act 1999, the Chief Inspector of Coal Mines authorised an independent engineering study of the seal arrangement. This study showed that, while the seal arrangement was capable of withstanding the 345 kPa overpressure, it could sustain damage that would render it unfit for further use as a seal.


Department of Natural Resources and Mines

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Relates to Queensland (QLD)

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Printed: 18 April, 2021.

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