Process for the continuous production of pipe from particulate materials

A process for continuously producing pipe which comprises:

• (a) coating a particulate material selected from the group consisting of sand and glass fibers and mixtures thereof with a mixture of an acid gas-curable resin selected from the group consisting of urea fomaldehydes, phenol formaldehydes, furans and furan copolymers and an oxidant selected from the group consisting of peroxides, hydroperoxides, hydrooxyperoxides, ring-substituted aralkyl hydroperoxides and perbenzoates, the amount of resin relative to the amount of particulate material being insufficient to reduce gas permeability of the compacted coated particulate material recited herebelow;
• (b) compacting and forming said acid gas-curable resin coated particulate material into an annular pipe configuration, which is gas curable, by forcing it into an annular space defined by the inlet ends of spaced inner and outer walls by means of an auger;
• (c) feeding said compacted coated particulate material in said annular pipe configuration along a path, the initial part of which is said annular space between said inner and outer walls;
• (d) feeding an acid curing gas, selected from the group consisting of sulfur dioxide and sulfuryl chloride, through perforations in one of said inner and outer walls and through said gas permeable compacted coated particulate material in said annular pipe configuration as said compacted coated particulate material in said annular pipe configuration moves along said path and is supported by said inner and outer walls to diffuse said curing gas through said compacted coated particulate material and cure said resin and form said particulate material into a self-supporting pipe having a porous wall;
• (e) gripping said self-supporting pipe at a position along said path downstream from the outlet end of said outer wall and drawing said self-supporting pipe along said path;
• (f) feeding a sealant, selected from the group consisting of asphaltic and resinous compositions, into said porous wall of said self-supporting pipe to impregnate said porous wall with said sealant, at a position along said path downstream from said outlet end of said outer wall;
• (g) applying a filament binding to the exterior surface of the impregnated pipe;
• and
• (h) recovering the cured and impregnated pipe.