Collarless drill pipe joint - has acme thread with effective centre line angularly offset relative to taper thread

摘要

A collarless joint for drill pipes uses an acme screw thread on the spigot and socket parts, both of which retain the original wall thickness. The centre line of the effective thread diameters deviates from that of a taper thread in that there is a continuous partial offsetting of that line in the direction of the other mating part. The inclined tooth flank of the spigot part has a concave shape and cooperates with a convex shape on the flank of the socket part.