Abstract: A pipe joint with a sleeve element, which has an internal thread, and with a spigot element, which has an external thread which can be screwed to said internal thread. One element has a constant pitch throughout and the other element, with two sections extending in each case from the ends of the threaded length is likewise provided with a constant pitch. The other element has more than two sections with a pitch which is constant within the section but is different from the first-mentioned element, it being the case that the pitch difference at least of one section is in the opposite direction, in terms of sign, to the rest of the sections. The pitch difference of one section is at least double that of the adjacent sections and in the screwed-together position, in the section with the large pitch difference, the thread play and the thread tolerances are compensated and the load flank of one corner tooth of this section, with the guide flank of the other corner tooth, produces the basic bracing.

Abstract: A boring rod connector with a journal element that has a tapered external thread section located between an outer shoulder and a journal face, a thread-free section located between the outer shoulder and the external thread section, and a thread-free section located between the external thread section and the journal face, and with a sleeve element that can be screwed to the journal element and has a tapered internal thread section located between an inner shoulder and a sleeve face, a thread-free section located between the inner shoulder and the internal thread section, and a thread-free section located between the internal thread section and the sleeve face. The thread-free sections of the journal element and the sleeve element located in the area of the inner shoulder that, when a screw connected exists, lie opposite to each other, have a different length than the thread-free sections of the journal element and the sleeve element located in the region of the inner shoulder.

Abstract: A pipe connector having a pin element having a tapered outer threaded section between an external shoulder and a pin end face, a first threadless pin section between the external shoulder and the outer threaded section, and a second threadless pin section between the outer threaded section and the pin end face. Provided for threaded engagement with the pin element is a box element having a tapered inner threaded section between an internal shoulder and a box end face, a first threadless box section between the internal shoulder and the inner threaded section, and a second threadless box section between the inner threaded section and the box end face. Suitably, the second threadless pin section and the first threadless box section in the area of the internal joint is at least twice as long as the first threadless pin section and the second threadless box section in the area of the external joint.

Abstract: A pipe connector having a pin element having a tapered outer threaded section between an external shoulder and a pin end face, a first threadless pin section between the external shoulder and the outer threaded section, and a second threadless pin section between the outer threaded section and the pin end face. Provided for threaded engagement with the pin element is a box element having a tapered inner threaded section between an internal shoulder and a box end face, a first threadless box section between the internal shoulder and the inner threaded section, and a second threadless box section between the inner threaded section and the box end face. Suitably, the second threadless pin section and the first threadless box section in the area of the internal joint is at least twice as long as the first threadless pin section and the second threadless box section in the area of the external joint.

Abstract: A pipe joint with a sleeve element and with a spigot element configured to be threadedly connected together to collectively absorb the load experienced by the joint over the threaded sections of the sleeve and spigot. By suitably selecting the leads and tooth gaps in the sleeve or spigot, it is possible for the guide flank at one thread end to be braced against the load flank at the other thread end thereby effecting maximum bracing at the edges of the thread and decreasing toward the thread center.

Abstract: A metallic coating is applied to threaded sections on the ends of plastic pipes that are to be forcefully screwed together. Droplets of a metal or metallic alloy are sprayed against the threaded sections at a high velocity, at a selectable angle of impingement, and within a zone of impingement. During the spraying, the pipe is turned and also moved relative to the zone of impingement in a longitudinal direction of the pipe. The resulting metallic coating on the pipes, beneficially, is porous so that such coating may contain lubricant, for instance. The apparatus for carrying out the spraying method includes a rotable pipe-holding device, and an arc metal spray unit having a nozzle whose direction of emission is adjustable.

Abstract: A screwed pipe joint with a bell for connecting two pipes of a drill pipe string.

Abstract: A drill pipe coupling includes a coupling member (2) having an unthreaded central section (13) with a cylindrical bore (26) therein and an outer shoulder (11,12) on each side thereof. Adjoining the shoulders are respective conical external threads for threading into an internal correspondingly threaded upset head section of a drill pipe formed as a bell elements and including end surfaces (9,10). The drill pipe has an undeformed cylindrical bore (14) connected to the threaded upset head. The drill pipe end surfaces (9,10) sealingly abut the outer shoulders (11,12) of the central section (13) when the pipes are joined together. The drill pipe has an intermediate section (16) adjoining the cylindrical bore (14) and has an inside diameter which decreases in the direction toward the threaded section (5, 6).