Quality Purging: Weld Purging dams are still fabricated on-site by welders to save money. They are often made from unsuitable materials such as foam, wood, paper and even tape.
These types of Weld Purging dams can often leak, become displaced and even burst into flames. Rework is then consequently necessary and in some cases welds have to be rejected. Displacing the oxygen with an inert gas before, during and after welding helps to create welds that are free from oxidation. However the Weld Purge dams should be made of materials that do not outgas water vapour or any other undesirable gases.
There are many reasons for using quality designed and manufactured Pipe Weld Purge Systems instead of homemade dams.
A customer of HFT® said: “I’ve seen many home-made devices. The rubber seal type always give a better seal and are more durable to heat, however burning foam dams release fumes. These are unhealthy and can contaminate the weld.
“More than once I’ve seen welders burn their hands whilst hurriedly removing a foam dam which had caught fire. Masking tape used in their place can often start peeling off whilst the welder is oblivious.”
“Foam dams can fall out during welding – a real sickener when you lift your hood to inspect your work.”
Foam is also highly porous and will be full of voids containing air, water vapour and maybe even hydrocarbons that will outgas as the dams become warm from the welding process.
HFT® manufacture a range of Tandem Weld Purging Systems in sizes 1” to 88” (25 to 2,235mm), a reusable method or welding reactive metal tube and pipe joints to ensure a very fast weld purge time and a very high quality weld root, free from oxidation, discolouration and coking.
Where Tandem Weld Purging Systems are unsuitable, Weld Purge Dams are available for pipe diameters from 6 to 88” (150 mm up to 2,235 mm) and offer a low-cost alternative to foam or cardboard dams that are still frequently handmade by welders on site.
Apart from the benefit of having a metallurgically sound weld, the difficulties of cleaning an oxidised weld are eliminated, saving vast amounts of money in labour and material costs as well as the disposal costs when pickling acids are used. Now there is no more reason to put welds at risk by using cheaper unsuitable materials.
