AM, EM, AQ, BA, ASW - IOM
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Ing.Ji
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í Jiránek
2.2.4 Liquid line
There are no special requirements for liquid piping.
2.3 Welding
Only hard oxygen-propane or oxygen-acetylene flame welding can be employed. Welding
material to be used is solder with minimum content of silver 5% (L-Ag5P). The welding is
performed with inner protection atmosphere of nitrogen (N2).
No chemicals are allowed to be
used for welding
. After connecting the piping and prior to the welding, the piping is filled with
nitrogen using pressureless method. The service valve of the outer unit must remain open to the
atmosphere during welding to prevent pressurization due to its warming. Sensitive elements of
the cooling circuit, especially the ball valves of the inner unit, must be cooled during welding
using a wet cloth covering the body of the valve. Proceed with care,
no moisture must get into
the cooling circuit under any circumstances
.
Instructions for ball valve welding
Removing the core of the
service valve of the outer unit
Inspect visually after welding and cooling of joints.
2.4 Leak Test
After welding put the core back to the service valve of the outer unit and pressurize it using
nitrogen to 10 bars (1,0MPa). Inspect tightness of joints using detection liquid. We recommend
attaching the air-pressure gauge to the service valve and after 24 hours check the pressure
which must be the same as after the pressurizing. In the case there is a pressure loss the
tightness of joints must be rechecked.
2.5 Vacuuming
After successful leak test the nitrogen must be emptied from the circuit and the system must be
vacuumed. We recommend using the 2-level vacuum pump. After the pressure is stabilized,
close the service valves. After 15 minutes check if the pressure did not increase again and
vacuum again for 30 minutes.
