Weld Purging: Replace Foam with Film for High Quality Welds The use of home made sponge foam purge dams for pipe weld purging is still very familiar throughout the welding industry. However, operators are unaware as to how the use of sponge foam can adversely influence the metallurgical strength of a joint. When sponge foam starts to warm up from the heat of the weld, the foam starts to outgas the harmful elements that exist throughout the foam (oxygen, nitrogen and water vapour). If the operator is unable to use a high quality Weld Purge Dam and wishes to use a low cost alternative, Huntingdon Fusion Techniques HFT® manufacture water-soluble Weld Purge Film®, ensuring all welders can achieve a great purge every time, at a reduced cost and without the introduction of harmful gases to the weld. Ron Sewell, Chairman for HFT® said: “Making a dam with Argweld® Weld Purge Film® is much easier than all of the complex cutting and shaving that goes into the self fabrication of a sponge dam. Simply cut off a length of film from the roll, greater than the diameter of the pipe and stick the surplus film to the water-soluble adhesive that is applied to the pipe beforehand.” “Cut costs, but don’t use inferior products such as paper or sponge, use superior ones like Argweld® Water Soluble Weld Purge Film®. Homemade dams made from material such as foam, sponge or paper can often lead to loss of welds when they leak or slip from position, oxidising the weld and causing unnecessary rework.” “Welders have even been known to burn their hands when removing a foam dam, which has caught fire. With the use of our low cost Weld Purge Film®, welders can ensure that their dams do not come loose during welding.” Weld Purge Film® Kits can be used on pipe diameters up to 900 mm (36”) and for temperatures up to 300ºC (572ºF) without the material burning, coming loose and losing the weld purge. The water-soluble Weld Purge Film® allows dams to be cut easily with the safety knife provided and once they are fixed into position using the water-soluble Weld Purge Super Adhesive® provided, produce an impenetrable purge barrier that can easily be washed away during hydrostatic testing of the pipe or just by normal wash-out. These affordable Kits will save operators high costs by minimising gas usage dramatically reducing purge time and eliminating the need to clean or even a failed weld. Weld Purge Film® Kits have been designed and developed by HFT®, containing product accessories needed to manufacture dams that will not come loose during welding. Other technical advantages of using water-soluble film instead of other materials include: The total transparency of the film dams, allows the welder to see the weld root as it is being laid. Vapour pressure of the film is very low and does not outgas harmful elements during welding that can mix with the hot metal and cause metallurgical defects. The Argweld® Film does not contain water, like paper and sponge products do. After welding, the water-soluble film is simply washed away and dissolved down to molecular level, leaving no trace.