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 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 pipeline with threaded pipes and a sleeve connecting the pipes which is hung in a drill hole for transporting a liquid and/or gaseous medium. An electrically driven pump or compressor is arranged at the start of the pipeline in the region of the base of the drill hole and the electric motor is supplied with electric power via a cable hung in the drill hole. In order to allow for large cable cross sections for the electric drive of a turbopump or a turbocompressor and to prevent impermissible loading of the cable, each sleeve of the pipeline has at least one groove extending in the longitudinal direction at its outer casing, the cable being guided in this groove.

Abstract: A gas-tight pipe connection includes a sleeve which has two internal thread portions which extend from the ends of the sleeve to a thread-free portion located in the middle of the sleeve. The sleeve includes a radially inwardly projecting web located in the middle of the thread-free portion and extending over a certain width. The web has end faces constructed as contact shoulders. A sealing portion each is provided between the internal thread portions and the contact shoulders. The connection further includes two pipes, each of which has in an end portion thereof a threaded portion constructed complementary to the internal thread portion of the sleeve. Each pipe also has a contact shoulder and a sealing surface arranged between the contact shoulder and the threaded portion. A tight metal seat is formed between the sealing surface of the pipe and the sealing portion of the sleeve.

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).

Abstract: Two metallic pipes to be sealingly interfitted are respectively provided with a plug-shaped male extremity and a socket-shaped female extremity having mating frustoconical peripheral threads and adjoining unthreaded annular peripheral formations closely contacting each other upon assembly. An annular end face of the male extremity and a confronting annular shoulder of the female extremity, lying in planes transverse to the pipe axis or on frustoconical surfaces of large apex angle converging toward the entrance end of the socket upon assembly, respectively have one or more annular rabbets and ribs centered on the pipe axis with profiles having outer or inner flanks parallel to that axis and closely juxtaposed in the fully assembled position in which the top of each rib abuts the bottom of an associated rabbet.

Abstract: A pin member with conical thread is threaded into a box or sleeve member having matching conical threading with abutment of the end of the box or sleeve against a shoulder on the pin member; that shoulder is continued into a groove in the pin member receiving a conically distorted polytetrafluoroethylene ring sealingly cooperating with a frustoconical surface of the box or sleeve member near its abutment end. The ring has been placed into the groove after having been heated to a temperature above the crystalline/amorphous transition temperature but below the liquification and decomposition temperatures.

Abstract: The surfaces of threads, sealing surfaces, and other load-bearing surfaces of oil field tubes or the like are treated by blasting surfaces to increase the roughness thereof to obtain a roughness of an average depth of from 7 to 15 micrometers under utilization of corundum or silicon carbide at a grain size of from 40 micrometers to 200 micrometers; a resin varnish is deposited onto the blasted surface for curing at higher than room temperature and including molybdenum sulfide at a layer thickness of from 5 to 20 micrometers. The varnish is cured in situ by heating.