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Pressure Test Instructions
Systems are pressure tested to ensure they are:
Safe – for this test a pressure above the system's maximum allowable
pressure (PS i ) is used
Leak tight – this test is at PS i .
Pressure testing is hazardous and should be carried out carefully:
The nitrogen used for pressure testing is an asphyxiant, so the area around
the system should be well-ventilated
High pressures are used, so all non-essential personal should be evacuated
from the area
Anyone carrying out the pressure testing should wear safety goggles.
Nitrogen and regulation
Dry (oxygen free) nitrogen (OFN) is used to achieve the pressures required for the
pressure tests because it is inert. You must never use oxygen for pressure testing -
pure oxygen at high pressure reacts violently with oil and will explode.
The pressure tests
Increase the pressure to approximately 5 bar g and check for leaks using leak
detection spray at this pressure initially – many leaks will be identified at this
pressure so you will not waste nitrogen and time. It is also safer to find leaks at a
lower pressure than the final test pressures.
Increase the pressure slowly to the strength test pressure and hold it for 15
minutes. Under the Pressure Equipment Regulation this strength test might need
to be witnessed by a notified body.
Using the nitrogen regulator
1. Ensure the regulator is
closed (wound fully anti
clockwise )
2. Open the cylinder valve
3. Slowly open the regulator
to the pressure required.
Do not use a regulator with an
output pressure much higher
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