It is important when welding metals such as stainless steel, titanium and zirconium that the welding zone is purged of oxygen even as low as 10 parts per million (ppm) before, during and immediately after welding, in order to achieve a clean, oxide free, zero colour weld.
During a recent trip to South America, Weld Purging Experts Huntingdon Fusion Techniques HFT were supporting their Exclusive Distributor and local customers when a discovery was made concerning the use of their Argweld Backing Tape.
One customer showed how the use of his former ceramic backing tiles and the tiny space available for the weld root formation, prevented adequate argon flow and caused the welding arc to blow back at the welder.
Luke Keane, Distributor Support for HFT said: "Ceramic backing tiles are designed for Submerged Arc Welding where oxidation is prevented by powder as opposed to argon, so the customers were using the wrong product for GTAW / TIG welding. A demonstration of Argweld Backing Tape followed, which allowed the argon to flow freely, eliminating the blow back of the arc that was happening previously and enabling the welders to produce a perfect root weld.”
Huntingdon Fusion Techniques HFT’s Weld Backing Tape comprises a 3-in (75mm) wide aluminium adhesive tape backing strip, in the centre of which is a 1-in(25mm) wide band of woven glass fibre matting.
Once the tape is positioned with the glass fibre matting under the centre of the weld joint, the welders can start their arc. The welding torch argon flow has plenty of space to move between the pores of the matting, which allows the welding arc to stabilise and start forming the weld root.
Measured by a Weld Purge Monitor, all contaminating oxygen below 100 parts per million (ppm) is removed and the stainless steel weld root is completed successfully, with the molten metal being cast onto the fibre glass with excellent side wall fusion and underbead profile.
The customer was so enthusiastic with the clean, metallurgically sound, non-oxidised weld that they placed a large order for HFT’s Weld Backing Tape for immediate delivery. Fortunately, the local Distributor had sufficient stock levels, were able to accommodate their wishes within hours and have them welding the same day.