Safe pressure testing of pipes
This guidance highlights the potential for explosions when pressure testing water or sewer pipes with high pressure air and provides alternative testing methods to reduce the risk.
This guidance highlights the potential for explosions when pressure testing water or sewer pipes with high pressure air and provides alternative testing methods to reduce the risk.
WorkSafe has investigated incidents involving high pressure pipes where:
Air is compressible, unlike water, so when used for high pressure leak testing, the compressed volume of air stored in the pipe system is significant.
In a pipe or joint failure, the volume of stored air will rapidly expand and release energy in an explosion. This puts employees and others close by at risk of serious injury or death.
Employers can eliminate the risk of explosion by hydrostatic pressure testing pipe systems using water or another suitable fluid.
Hydrostatic pressure testing only requires a relatively small amount of liquid to develop a high pressure. It is therefore only able to release a small amount of energy in a pipe or joint failure.
When testing pipes for system integrity and locating leaks, hand-operated testers should be used. This is because hand-operated testers have a lower compression rate, which results in a less severe explosion should a joint fail during testing.
Where it is not reasonably practicable to undertake hydrostatic pressure testing, compressed air pressure testing should be conducted to a maximum pressure (including pressure spikes) of 50 kPa.
If there are exceptional circumstances that necessitate the use of compressed air to a pressure greater than 50 kPa, additional protective risk control measures should be implemented.
These measures should be inspected and certified by a competent person, such as a qualified engineer.
Protective measures should include:
Ensure end-caps are installed according to the manufacturer's specifications, including tightening fasteners to the specified torque using appropriate tools (e.g. calibrated manual torque wrench and correct size sockets).
Employers should ensure that, before undertaking pressure testing, employees:
As necessary, employees should be supervised by a competent person to ensure the work is done safely.