Stainless steel liner in oil well pipe

Claim 1

In combination with steel oil well pipe having a bore defining an axis (a) a corrosion-resistant, metallic liner within the pipe, and (b) a metallurgical bond intimately joining the liner to the pipe bore, said bond characterized by an intimate intermolecular diffusion connection extending circumferentially continuously along substantially the entire axial length between the liner and the pipe bore for preventing formation and collection at the bond location along the bore of gaseous hydrogen resulting from diffusion through the bond of atomic hydrogen, (c) the major length of the pipe consisting of steel which is relatively non-corrosion resistant, and the pipe also including an annular end portion the surface of which is corrosion resistant, said end portion being threaded and having a bore, said liner bonded to the bore of the pipe major length and also to annular bore extent of said pipe end portion, said end portion welded endwise to said major length of the pipe at an annular joint therebetween, said liner bridging said joint, said annular bore extent being axially tapered between 4° and 15° relative to the bore axis, (d) said annular bore extent located between said joint and an interior zone of the pipe end portion radially inwardly of said threading, the liner and said axial bore extent terminating proximate said joint, the joint extending substantially radially between the liner and the outer surface of said end portion, (e) said liner comprising a corrosion resistant steel cylinder and a metallic film on the cylinder outer surface, the bond formed between said film and the pipe bore.