Before the industrial revolution all sort of metal work was being done by other craftspeople than blacksmiths. Blacksmiths didn't make clocks or jewellery for example. The early pipemakers are well documented in the articles I linked above.

OK Thompson, I know the images you mean now, they were well before the union pipes. Early warpipes I suppose. Seán Donnelly's booklet 'The Early history of Piping in Ireland' (ISBN 0 9509743 9 0) goes into that and deals with Derricke's image of the 'pyer' on pp 33-34