Helically welded 'Plain Iron' (pre-Bessemer) barrels were an attempt to improve on "Cast steel" Huntsman hot-rolled crucible steel process of 1742. To form a pipe or barrel, a sheet was folded over a mandrel and the long edge hammer welded.



They tended to split at the seam



W. Ketland 20b SxS flintlock c.1815 helically welded



By the time of the 'Premier' bike, fluid steel by Cockerill, Siemens, Krupp and others was already in common use

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