Inflatable Purge System

An insulated, heat-covered inflatable purge system is available for purging pre-heated pipes. The system uses fire-retardant Proban cotton. This material resists scorching and burning. An armoured connection hose improves durability. Reinforced stitching and crimping increase tear resistance. Strong eyelet pull loops help position the system inside the pipe. A bypass hose allows an additional gas inlet or exhaust. Special hose barb connections allow quick connection to a gas source.

The system reduces gas flow during hot passes to about 5–10 LPM. It is available for pipe diameters from 2” to 96”.

Operation

Step 1
Insert the deflated purge system into the pipe using the pull tags.

Step 2
Place the two purge dams on either side of the weld joint. Glow tape between the dams indicates correct positioning. Open the argon supply to a flow rate of 5–10 LPM. The dams inflate and seal the pipe.

The pressure then opens the purge valve. Purging begins in the space between the pipe and the dams. Air inside the pipe moves through the exhaust outlets and away from the weld area. Continue purging until oxygen levels fall to the required level for welding. Use a purge gas monitor to check oxygen levels.

Maintain a constant inert shielding gas flow of about 3–5 LPM. This keeps positive purge pressure during welding.

Step 3
After welding, allow the joint to cool below oxidation temperature. Stop the argon supply. The purge system will deflate. Remove the system from the pipe.

Applications

The purge system suits welding of stainless steel and other reactive metal pipework. It also supports autogenous weld fit-ups. The system works with scheduled pipework that requires a gap between two bevelled pipe ends.

Standard purge bags operate up to 100 °C. Heat-resistant purge bags withstand 350 °C continuously and up to 500 °C for short periods.