I am currently reviewing our GTAW aerospace welding process to the requirements of AWS D17.1, in particular welder qualification. Currently, our welders use an apparatus to weld the test coupons. Our typical test coupons are 0.025 or 0.032 inches thick. The apparatus is essentially heavy steel plates that hold the test pieces in place. Along the weld joint, the test pieces sit on a thin piece (approx. 0.032 inches thick) of copper plate that has several holes in it to allow the backing gas to flow through, essentially the copper acts as a conduit for the backing gas.

My question is:

Is this test apparatus and copper conduit considered backing material?

If so, then the welder is not qualified to weld without backing. Reference AWS D17.1 Table 4.4. The welder must weld his coupons without backing in order to qualify him to weld with or without backing.

As per the AWS A3.0 Definition. Backing is defined as:

A material or device placed against the back or side of the joint adjacent to the joint root, ... to support and shield molten weld metal. The material may be partially fused or remain unfused during welding and may be either metal or nonmetal.

I guess the loop hole in the definition is that backing is used "to support and shiled molten weld metal". The copper is full of holes and doesn't shield or suppport the molten weld metal. Therefore the copper and apparatus isn't considered backing.

Any comments or assistance in clarifying this is appreciated.

Regards,

Tyler