Abstract: A method for manufacturing a long length of coiled metal tubing or the like using friction stir welding. Successive lengths of metal strip are friction stir welded using a three-pass welding technique to eliminate any edge defects in the resulting strip. The method includes one or more three-pass friction stir welding routines, each of which includes a first pass performed using a tool having a first rotational direction and a spiral bit pattern corresponding to the first rotational direction; a second pass using a tool having a second rotational direction and a spiral bit pattern corresponding to the second rotational direction; and a third pass using a tool having said second rotational direction and a spiral bit pattern corresponding to the second rotational direction.

Abstract: A method of evaluating defects in a friction stir welded seam is provided, the method including: providing a welded sheet of metallic stock, the sheet having a top edge and a bottom edge, opposed side edges, and a joining seam formed between the opposed side edges by means of friction stir welding; isolating a preselected test specimen from the sheet of welded metallic stock, the specimen comprising either the top edge or the bottom edge and a test portion of the seam, with the test portion extending from an intermediate point to either the top or bottom edge and having a longitudinal axis, so that said test portion is disposed perpendicularly to the longitudinal axis, thereby establishing a test specimen face and a weld root; and detaching the specimen from the sheet and then testing the integrity of said weld root.