Pipe joint and related method

1. A spigot member for a pipe joint, the spigot member comprising:

a tubular plastic body wall having an internal surface and an external surface and a longitudinal axis;

a metal reinforcement encased within the tubular plastic body wall;

a plurality of plastic ribs extending from the external surface of the tubular plastic body wall and forming a gasket channel, including a first circumferentially extending solid plastic rib, a second circumferentially extending solid plastic rib spaced apart from the first circumferentially extending solid plastic rib, and a third circumferentially extending solid plastic rib positioned between the first circumferentially extending solid plastic rib and the second circumferentially extending solid plastic rib, the third circumferentially extending solid plastic rib defining a rib diameter that is smaller than respective rib diameters defined by each of the first circumferentially extending solid plastic rib and the second circumferentially extending solid plastic rib, the third circumferentially extending solid plastic rib is positioned nearer to the first circumferentially extending solid plastic rib than to the second circumferentially extending solid plastic rib, an annular gasket positioned in the gasket channel, the metal reinforcement is positioned so as to be located radially inward of at least a portion of the gasket.

2. The spigot member of claim 1 wherein the gasket includes a first radial wing extending outward in a region that lies between the third circumferentially extending solid plastic rib and the first circumferentially extending solid plastic rib, and a second radial wing extending outward in a region that lies between the third circumferentially extending solid plastic rib and the second circumferentially extending solid plastic rib.

3. The spigot member of claim 2 wherein the second radial wing extends outward further than the first radial wing and the second radial wing has an annular width that is greater than an annular width of the first radial wing.

4. A plastic pipe having the spigot member of claim 1 connected at one end thereof.

5. A multi-pipe structure including the plastic pipe of claim 4 , comprising:

the spigot member of the pipe of claim 4 positioned within a bell end structure of a second plastic pipe, an outer surface of the gasket pressed against an inner surface of the bell end structure.

6. The multi-piece pipe structure of claim 5 , wherein the bell end structure comprises:

a tubular plastic body wall having a metal reinforcement ring encased therein.

7. A method of producing the spigot member of claim 1 , comprising:

producing a spigot portion of plastic material that defines the tubular plastic body wall and having a flap with an attached end and a free end;

inserting the metal reinforcement beneath the flap of the spigot portion; and

subsequent to insertion, sealing the flap of the spigot portion to a remainder of the spigot portion to completely encase the metal reinforcement within plastic.

8. The method of claim 7 wherein:

the spigot portion is produced by:

extruding a spigot profile as an elongate strip;

cutting the elongate strip to a set length;

rolling the cut elongate strip to a desired diameter with end portions spaced apart to provide a gap therebetween;

the metal reinforcement is inserted after the rolling step and traverses the gap;

the sealing step is performed in part by overmolding plastic to fill the gap and in part by applying a plastic weld seal to the free end or heat welding the free end.

9. The method of claim 7 wherein:

the spigot portion is produced by molding a spigot as a complete cylinder form having the flap with the free end;

the metal reinforcement is inserted beneath the flap after the molding step; and

the sealing step is performed by applying a plastic weld seal to the free end or heat welding the free end.

10. A spigot and bell pipe joint structure, comprising:

a spigot member including:

a tubular plastic body wall having an internal surface and an external surface and a longitudinal axis;

a metal reinforcement encased within the tubular plastic body wall;

a plurality of plastic ribs extending from the external surface of the tubular plastic body wall and forming a gasket channel, including a first circumferentially extending solid plastic rib, a second circumferentially extending solid plastic rib spaced apart from the first circumferentially extending solid plastic rib, and a third circumferentially extending solid plastic rib positioned between the first circumferentially extending solid plastic rib and the second circumferentially extending solid plastic rib;

an annular gasket positioned in the gasket channel, wherein the metal reinforcement is positioned so as to be located radially inward of at least a portion of the gasket;

a bell member including:

a tubular plastic body wall;

a metal reinforcement ring located within the tubular plastic body wall;

where the spigot member is inserted within the bell member, the metal reinforcement ring of the bell member overlapped with the metal reinforcement of the spigot member, an outer portion of the gasket pressed against an inner surface portion of the tubular plastic body wall of the bell member, the inner surface portion located radially inward of the metal reinforcement ring of the bell member.