Tips For Pressure Testing

Unless there are special circumstances you should always use water to carry out pressure testing. In some cases you can carry out pneumatic pressure testing. This uses inert gas or air but needs to be carried out under extremely carefully controlled conditions.

Liquids such as water can only be very slightly compressed and only need a tiny amount of energy in order to increase the pressure being used.

Gases and air can be compressed so a great deal more energy must be used in order to produce enough force to test pressure. Compressed air or gas stores 200 times more energy than that stored in compressed water.

If a component such as a pipe or joint fails when it is being pressure tested using gas a large amount of damage can be caused. If testing needs to be carried out in buildings this can mean that air or gas testing must be used as water leakage would cause too much damage to the building.

The most extensive way to test for leaks is to carry out a pneumatic leak test first and then a hydraulic leak test which will discern the extent of any damage.

Hydraulic pressure testing can never be used in some buildings such as listed buildings as water could cause damage to the surroundings. In such cases it is acceptable to carry out a pneumatic pressure test if a pneumatic leak test has been carried out first.

If this is the chosen route then it’s the employers responsibility to make sure that all employees are aware of what their health and safety responsibilities are. Employers are required by the Health and safety at work act to provide all the necessary information, supervision of work, training and instruction. It’s the employees responsibility to make sure that they do not carry out their work in such a way as to cause danger to their own lives or the lives of other employees.

There are many regulations and requirements in British law regarding water valves and testing. For example water systems must be fitted with the correct number of servicing valves and drain taps. In addition water systems must be able to be drained easily.

Pipework must be able to be isolated with stop valves in some places and hydraulic testing must take place. This is to check for faults and make sure that all the valves are working well.
Any water system must be able to withstand pressure one and a half times greater than that it was designed to withstand.