Abstract: A method of expanding a tube of plastics material in which a longitudinally travelling tube is progressively diametrically expanded in internal fluid pressure in an expansion zone between an upstream plug and an expandable downstream plug. Expansion of the tube is controlled in response to parameters which directly or indirectly indicate variation in the relative velocity at which material is delivered to and removed from the expansion zone, such as detecting upstream velocity, early expansion diameter, axial force on a sizing device or the tube diameter just before the expansion zone.

Abstract: The invention provides, in a first form, an expandable plug for regulating pressure or flow within a tube. The plug has an inflatable bladder (12) for diametral expansion by internal fluid pressure introduced by inlet (14). The plug is reinforced by an envelope (26) of cords (28) which spread laterally upon inflation of the bladder to provide diametral support to the bladder. In a second form of the invention, an inflatable plug positioned in a tube of internal diameter d is controlled according to the equation P.sub.p =.DELTA.P+P.sub.d wherein P.sub.d is the internal pressure in the plug, .DELTA.P is the differential pressure across the plug and P.sub.d is the plug free expansion pressure for diameter d.

Abstract: A circumferentially or biaxially oriented plastics pipe comprising a body with an integral socket at one end thereof The socket has a wall of lesser axial draw than the body of the pipe.

Abstract: An apparatus for slitting foil (14) of thermoplastics material comprises a mover to move the foil (14) through a slitting station (1), the slitting station (1) having a first slitting blade (2) having a sharp front edge (4) located extend transversely through the path of the moving foil (14), and that part (5) of the blade (2) behind the front edge (4) having each side (6), sharped to be non-intrusive into the slit and melted thermoplastics material foil (14), a heater (8,9) to raise and maintain a temperature of the slitting blade (2) to a temperature equal to or above a melting temperature of the thermoplastics material foil (14) selected to be slit by the slitting blade (2), and a cooling blade (3) located behind and aligned with the slitting blade (2) and having two sides each adapted to be aligned with the corresponding side of the slit of thermoplastics material foil (14) and provide by both contact and radiant heating effects, a substantial cooling effect.

Abstract: A hose coupling which has an integrally moulded lip which has an innermost surface defining a frusto-conical shape and a portion of reduced thickness to provide for pivoting freedom of the lip to effect both a grip and seal of a hose that can be inserted therethrough. The lip has axially extending tails which are segmented allowing for expansion or contraction as necessary of the lip but providing a limit to the pivotal freedom of such lip.