A man died at a Sydney construction site last month after a pressurised pipe exploded during leak testing.
The following Safety Alert highlights the dangers of working with pressurised pipe and some of the control measures that can be used to protect workers.
Piping systems can pose significant safety risks. Air, unlike water, is compressible. This means that when used for high-pressure leak testing, the compressed volume of air stored in the pipe stream is significant.
In a pipe or joint failure, the volume of stored air will rapidly expand and release energy in an explosion. This put employees and other nearby at risk of serious injury or death.
Key hazards to be aware of include:
- The failure of pipes and/or fittings under extreme pressure; and
- Failure to identify if the installation is under a pressure test
Recommended control measures
The most important control is to make every effort to ensure the line is depressurised before removing any end piece.
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; therefore, it is only able to release a small amount of energy in a pipe or joint failure.
If using compressed air pressure testing, companies are advised to adopt additional control measures.
For example, in circumstances 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.
Where exceptional circumstances 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 an appropriate qualified and competent person, such as a qualified engineer.
Protective measures should include:
- Appropriate procedures, equipment, materials and pipe end supports
- Using a designated test zone where possible or establishing an exclusion zone around pipes that cannot be moved.
- Ensure endcaps are installed according to the manufacturer's specifications.
General Rules to apply
Companies are also advised to apply the following general rules
- No person should ever stand directly in line with a cap or plug being removed.
- Always assume that pipe is under pressure until proven otherwise.
- Always communicate to your fellow employees what lines are under testing.
- Remember to apply isolation procedures when undertaking these works.
Always remember that multiple crews may be testing the same lines at different times. Overall coordination and control of pressure testing is required to be overseen by a supervisor or company representative on site.
It is vital that AMCA members ensure that all employees engaged in piping activities receive appropriate training, including all aspects relating to:
- Appropriate testing methods
- Equipment to be used
- All hazards and risks associated with the task
- Relevant inspection and testing procedures.
Employees should also have a comprehensive understanding of the specifications and procedures of the relevant water agency.
All employees should be supervised by competent person to ensure work is done safetly.