A pipe for conveying solid matter, particularly for conveying concrete. The pipe has a cylindrical middle portion and a double-layer welding neck with annular coupling flange at each end of the middle portion. The inner layer is replaceably clamped in the outer layer in a positively locking and frictionally engaging manner. This is accomplished by a roof-like bevel of the inner layer which is engaged by a corresponding inner groove of the outer layer which is of limited elasticity. The inner diameter of the inner layer may be smaller than the inner diameter of the cylindrical middle portion.

An erosion resistant pipe flange assembly for preventing erosion of metal pipe flanges connecting two joints of pipe. The erosion resistant pipe flange assembly includes a flange section, a reducer section integrally formed with said flange section, and a replaceable liner for preventing erosion and abrasion of the interior of said pipe flange assembly.

In a lined pipe, permeated gases trapped between the liner and the outer casing are vented by a collar received between the liner flange and the pipe flange which defines at least one predetermined channel through which the gases may exit.

A bone fusion mass constrainer is useful for promoting fusion between a pair of adjacent vertebrae. The bone fusion mass constrainer includes a generally cylindrical cage assembly having an internal cavity with open top and bottom surfaces. The cage portion is intended to be positioned in contact with the cancellous bone of the adjacent vertebrae. A pair of horizontal platforms extend out from the cage assembly and provide support for the vertebrae by contacting the harder cortical bone of the endplates of the vertebrae. Bone graft is inserted into the cavity where it contacts the cancellous bone of the adjacent vertebrae and promotes fusion between the two vertebrae. An end cap is provided over the proximal opening of the cage assembly to prevent migration of bone graft out from the cage. The bone fusion mass constrainer also includes a pair of blades which can be extended outwardly from the cage assembly and into the cancellous bone of the adjacent vertebrae in order to prevent migration of the device from between the vertebrae.

Stiffener designed for fitting to a piping consisting of a flexible conduit for use in a marine environment, carying a hot fluid, the said stiffener comprising a flexible casing located at least partially over the said flexible conduit, having structure (15) for dissipating the heat at the interface between the stiffener and the flexible conduit (3).