Safety Main Stopper Co., Inc.



The “4GS” System and the “3GS” Stopper

Backup dams to insure an inert atmosphere during tungsten arc welding is an established and well known practice. Various methods have been devised, but none is as fast and efficient as the Type "4GS" Inflatable Purge Dam Method.

Two deflated Purge Dams, joined together, are pulled from the open end of a pipe so that one dam is located on either side of the area where the weld is to be made. The purge supply line is built into and bypasses one of the Purge Dams. The Purge Dams are inflated and purging media may then be fed between the dams. The dams are then partially deflated and pulled to the next weld area and the same procedure is then repeated. See the illustrations that follow.

There is no time consuming cutting, fitting, or taping of dams at each welding area as with other methods. Merely pull the Inflatable Purge Dams to the next weld area and you are ready to begin purging. There is no danger of the dam collapsing or tearing either because once the dam is inflated, it stays in place until YOU move it.

Type "4GS" Inflatable Purge Dams can be used over and over again. Their rugged heavy-duty polyester outer covers are long lasting and durable. Dams for 2" diameter to 72" diameter pipe are available and may be purchased either individually or in pairs.

All accessories for the Type "4GS" Inflatable Purge Dams may be purchased individually. Inflating air line assemblies and purge feed line assemblies are furnished in 12 ft. lengths in all diameters. All inflating air lines are furnished with a pressure gauge. All lines can be made to any length required.

The following drawings illustrate the various Inflatable Purge Dam Systems available.




  1. DO NOT pull bags by air lines, use pulling loop only.

  2. DO NOT inflate bags over recommended pressures.

  3. DO NOT allow sparks, hot metal or welding slag to contact bag or tubes.

  4. DO NOT expose bag or tubes to temperatures in excess of 150 F.

  5. Test each bag by inflating to recommended pressure for 1/4 hour immediately before each use. See detailed literature for further safety measures.

  6. Inert purging gases displace oxygen, therefore, use with adequate ventilation and post warning signs in welding area.

  7. Welding Safety Practices as recommended by the American Welding Society must be observed at all times.

  8. Place bags at least 8 ft. from welding site.


Main Bags Type B | . Main Bags Type C | . Purge Dams | . Directional Gas Bags Type D

Safety Main Stopper Co. Inc. • 523 Atlantic Ave, Brooklyn, NY 11217 • TEL: 718-875-4427 • FAX: 718-625-4805