22.2.1 At each Annual Survey, leak testing of plant piping is to be performed using the
ordinary operating pressures for oxygen and acetylene respectively. The gas supply
to the plant piping is to be stopped by the central regulator being closed and the
pressure in the plant piping is to then remain constant for at least eight hours. If
pressure drop occurs in oxygen and/or acetylene plant piping, the plant is to be
checked and repaired. The tests are to be carried out to the satisfaction of the
Surveyor.
22.2.2 At each Special Survey, all plant piping is to be blown-through and be leak tested in
accordance with the following:
- Dry and oil-free nitrogen is to be used for leak testing
of low-pressure acetylene and oxygen piping and the test pressure is to be
12 bar. After eight hours, the pressure drop is not to exceed 0,4 bar.
- Acetylene piping on the high-pressure side is to be leak
tested with dry and oil-free nitrogen at 25 bar. 25 bar relates to the
maximum cylinder filling pressure at 15 °C. Where it is proposed to use
cylinders with a higher filling pressure, the test pressure is to be agreed
with LR.
- Oxygen piping on the high-pressure side is to be leak
tested with 200-bar oxygen or dry and oil-free nitrogen. 200 bar relates to
the maximum cylinder filling pressure at 15 °C. Where it is proposed to use
cylinders with a higher filling pressure, the test pressure is to be agreed
with LR.
- All valves, joints and other connections are to be
checked for leakage by appropriate means.
The tests are to be carried out to the satisfaction of the Surveyor and be carried
out by an appropriately qualified person.
Note Prior to the leak tests, blow-through of acetylene and oxygen piping is to be
carried out with dry and oil-free nitrogen. Nitrogen is to be blown in from the
high-pressure side and be carried off at the outlet station. The outlet station(s)
(torch, stop valves, regulators, manometers, flash back arrestors and non-return
devices) is to be removed during the blow-through process. At blow-through, the
pressure is to be gradually increased to approximately 12 bar and the blow-through
process is to continue till dirt no longer escapes from the pipe. High-pressure
pipes are to be blown-through separately. The risk of injury to personnel or damage
to the plant from blown-through gas and dirt is to be considered.