Whats Different About Welding Aluminum Pipe?
Unfortunately, neither backpurging nor consumable inserts works well for producing X-ray-quality welds in aluminum piping. In fact, the technique of “pulling” a consumable insert doesn’t work at all on aluminum. The reason is fairly simple to understand. If you look atFigure 2, you can see that the weld joint area has a large surface where aluminum oxide can form. However, the only areas where the arc will strip the aluminum oxide from the surfaces to be welded are those within the tungsten electrode’s line of sight, so to speak. So in many areas, the arc can’t strip the oxide off the surface of the aluminum. Because of this, the consumable insert won’t melt and flow out easily, and it can’t be pulled. You can weld aluminum pipe joints using an open-root technique, but it’s more difficult to do than it is with steel. Aluminum’s high thermal conductivity means that the weld pool is larger than it is in steel. The weld pool also is more fluid, so it’s harder to control the molten pool. O
