Kemon, Palmer & Estabrook
Tube expander utilizing hydraulically actuated pistons
 An apparatus for expanding a tube or pipe by axially compressing an annular resilient element to cause said element to radially expand into engagement with the inner surface of the tube or pipe. The compressing of the resilient element and its radial expansion is caused by a main piston and cylinder structure which is subjected to fluid under pressure. A secondary or impact piston is provided in the main piston for applying higher stresses to the tube or pipe through the resilient element. The resilient element is interposed between a plurality of spaced annular ring members which constitute guide means therefor. 
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James Hilbert
Anderson