Method of manufacturing a clad tubular product by extrusion

A method of manufacturing an internally clad tubular product employing a tubular host having a first and a second end, comprising:

• (a) plating the internal surface of the tubular host with a low melting point bonded metal alloy;
• (b) inserting a tubular cladding member into the plated tubular host the tubular cladding member having a first and second end, the tubular host and cladding member being of substantially the same length;
• (c) circumferentially welding the first end of said cladding member to the first end of said tubular host;
• (d) welding a circumferential bag between the second end of said tubular host and the second end of said tubular cladding member to form a sealed subassembly, the bag being in the substantial shape of one-half of a toroid cut in a plane perpendicular the circular axis providing an inner and outer circumferential surface, the inner circumferential surface being welded to the second end of said tubular cladding member and the outer circumferential surface being welded to the second end of said tubular host;
• (e) evacuating the annular space between the exterior of said cladding member and the interior of said host and charging it with inert gas by attachment of apparatus to said bag in a manner to substantially remove all water and oxygen;
• (f) heating the subassembly from about 1,650.degree. F. to about 2,200.degree. F.;
• and
• (g) forming the heated subassembly in a mill to metallically bond the cladding member to the tubular host.

A method of manufacturing an internally clad tubular product employing a tubular host having a first and a second end and having a cylindrical faying surface and tubular cladding member having a first and a second end and having a cylindrical faying surface, comprising:

• (a) plating one of the faying surfaces with a low melting point bonding metal alloy;
• (b) assemblying the tubular members one within the other so that their faying surfaces are juxtaposed;
• (c) circumferentially welding the first end of the tubular host to the first end of the tubular cladding member;
• (d) welding a circumferential bag to the second end of the tubular host to the second end of the tubular cladding member, the bag being in the substantial shape of one-half of a toroid cut in a plane perpendicular the circular axis providing an inner and outer circumferential surface, the inner circumferential surface being welded to the second end of said tubular cladding member and the outer circumferential surface being welded to the second end of said tubular host;
• (e) purging the annular space between the faying surfaces of oxygen and water by attachment of apparatus to said circumferential bag;
• (f) heating the assembled members to the melting temperature of the bonding metal alloy;
• and
• (g) applying pressure between the assembled tubular members to bond the faying surfaces.