Patent ID: 8382467

Claim:
A multiple part mandrel for forming a hollow body, the multiple part mandrel comprising: a plurality of sectors, each sector having an outer face, a skin on the outer face, a bearing structure extending from an inner face, and a pair of opposed side returns at longitudinal sides of the sector, wherein the mandrel is symmetrical about a central axis defining an axial direction of the mandrel, when the sectors are assembled so that the side returns of adjacent sectors face each other, each of the side returns includes a recess in an outside surface of the respective side return, spaced from the skin of the respective sector, and an inflatable O-ring disposed in each of the recesses, and the recesses of the adjacent side returns in the mandrel are offset with respect to each other in a radial direction of the mandrel, wherein inflation of the inflatable O-rings urges adjacent sectors together at the skins of the sectors, to seal the adjacent sectors of the mandrel at the skins of the adjacent sectors.