A worker was seriously injured while performing a pressure test on a length of plastic pipe.
According to a safety alert by the NSW Chief Inspector of Mines, a pipe blanking cap struck the worker after the crimped connection between the ferrule and pipe failed about midnight on November 26. The injured worker suffered serious leg and hand injuries and was taken to hospital by ambulance.
“The incident occurred while testing the integrity of nitrogen delivery pipes after a load haul dump vehicle dragged them from underground to the surface of the mine,” the report said.
“The test procedure was to cap both ends of the pipe assembly and pressurise the assembly with compressed air to approximately 800kPa. Ball valves were used to prevent the air from
escaping while a pressure gauge was fitted to the other end.
“Leaks were detected by a pressure loss over a 15-minute period.”
A level 3 investigation into the incident is underway.
“Pressure equipment integrity is the sole engineering control in preventing the uncontrolled escape of a pressurised substance. As such, pressure equipment integrity is crucial in preventing injuries,” the alert said.
The following recommendations were made for when pressure testing the integrity of pressure equipment (including pipe assemblies):
1. establishing safe work systems that protect workers in the event of the pressure equipment failing the test in a catastrophic manner. Where possible consider engineer controls such as
guards or remove people from the test area.
2. all reasonably foreseeable failure modes of the pressure equipment and how workers may be harmed.
3. pressure pipe and other pressure equipment not being tested by using compressible gasses. Pressure testing should be carried out using a liquid, where possible. Compressible gases store more potential energy than incompressible liquids.
4. test equipment and safe work procedures for pressure equipment being confirmed by a competent mechanical engineer, to ensure all hazards and risks have been identified and adequately controlled.
5. the selection of appropriate and fit-for-purpose test and measuring equipment, including pressure rating of components.
6. a work environment that is free of obstacles and other hazards.