Abstract: This invention related to a pre-formed channel piping system. This invention relates to a pre-formed channel piping system to facilitate a combination utility fluid system with an underground communication network. The pre-formed fluid pipes include a channel for carrying communication components in a protected casing.

Abstract: This invention related to a pre-formed channel piping system. This invention relates to a pre-formed channel piping system to facilitate a combination utility fluid system with an underground communication network. The pre-formed fluid pipes include a channel for carrying communication components in a protected casing.

Abstract: A weldable plastic tube (10) has at least one end designed to be butt welded and designed for the conveyance of a fluid producing a drop in mechanical resistance of said weldable plastic. The tube comprises an internal layer (12) for protection of the plastic of the tube from contact with the fluid conveyed and adjoining said welding end has a terminal section permanently covered with an external reinforcing sleeve (13) also of weldable plastic to participate in the butt welding of the tube. The sleeve has a thickness such as to make the mechanical resistance of the tube section nearest the welded end at least equal to the mechanical resistance of the tube not in contact with the fluid when in contact with the fluid in the welding zone which will be without the internal protective layer.

Abstract: Thermoformed intake duct (1) made of non-woven material and including flanges (6, 7, 8, 9) parallel to the longitudinal axis of the duct, projecting from the outer surface of the duct, a first portion (4) of the duct being formed in the form of a first bellows, a first bellows-shaped portion (4) having two longitudinal flanges (6, 7) diametrically opposed along a first diameter (D2), characterized in that the duct includes at least a second bellows-shaped portion (5) having two longitudinal flanges (8, 9) diametrically opposed along a second diameter (D3) of the duct which makes, with respect to the first diameter (D2) of the two flanges (6, 7) of the first bellows-shaped portion, a non-zero angle, and especially 90°.

Abstract: High-pressure pipe element made of a hooped tube for making lines referred to as kill lines and choke lines that equip oil production installations, notably offshore. The high-pressure pipe element is an assembly consisting of two connections (3) and (4) respectively welded to the two ends of a metallic tube (1). The metallic assembly is hooped. Hooping (2) covering tube (1) comprises a sufficient number of hooping layers to withstand a determined internal pressure. Transition zones (5) and (7) in the vicinity of the welds comprise additional hooping layers.

Abstract: The invention relates to a bending and holding aid, especially for pipes, cables and lines consisting of a bendable hollow body that is closed, at least in sections, open at both front ends having a substantially tube-shaped enveloping surface, which consists of individual articulated members connected by means of connecting elements with flexible angles, where the freely accessible front ends of an articulated member form a sharp angle whose opening is oriented in the direction of the connecting elements. The bending aid is configured such that the connecting element is a defined one-dimensional joint and that on the side of the bending aid opposite the connecting elements catching elements are disposed that connect the adjacent articulated members so as to interlock, without additional holding device, when the bending aid is bent.

Abstract: An exemplary embodiment of the invention is a kit for installing an underground piping system. The kit includes a protective conduit having flexible piping contained therein and a plurality of sealing members. The installer positions the protective conduit and flexible piping as a single unit thereby facilitating installation.

Abstract: Pipes or pipelines insulated on their surface or surfaces are described. The pipes or pipelines may be for submerged service, below the surface of water. The insulation chosen may be an epoxy substantially free of phenolics and one or more of glass or ceramics. The coating may be an abrasion resistant coating. Such pipes or pipelines are generally intended for the transport of fluids, which can include natural gas, natural gas liquids, crude oil, refined products, chemicals, combinations thereof, and the like.

Abstract: An outlet tube comprising a unitary material sheet folding into a rectangular shape and having overlapping ends secured with rivets, the outlet further including flanges extending outwardly from one end of the walls of the rectangular shape, and slots at the upper and lower fold lines to accommodate irregular shaped holes via bending of the sides of the outlet tube. Three sizes of flat blanks handle all gutter common hole sizes, and these blanks are made by one die assembly, which include holes on flange to allow riveting to the floor or the gutter.

Abstract: A transport pipe for solid materials has a single layer pipe section having a threaded first end and a thread second end. The pipe section has a hardened inner mantle. A first coupling collar having a first threaded collar is threaded onto the threaded first end. A second coupling collar having a second threaded collar portion is threaded onto the threaded second end. Wear-resistant layers are located in the region of the first and second coupling collars. Seals in the form of, for example, O-rings, U-shaped profiles, or flat packings, can be provided between the coupling collars and the pipe section.

Abstract: This invention relates to flexible tubular conduits or pipes particularly in situations where the conduits need to withstand relatively high pressures. In such cases, the conduits are reinforced by helically wound armor which is compliant in flexure, and profiled to allow each subsequent turn to interlock with the previous turn.

Abstract: High-pressure pipe element made of a hooped tube for making lines referred to as kill lines and choke lines that equip oil production installations, notably offshore. The high-pressure pipe element is an assembly consisting of two connections (3) and (4) respectively welded to the two ends of a metallic tube (1). The metallic assembly is hooped. Hooping (2) covering tube (1) comprises a sufficient number of hooping layers to withstand a determined internal pressure. Transition zones (5) and (7) in the vicinity of the welds comprise additional hooping layers.

Abstract: A floor panel for use in an air handling unit that provides a thermal barrier to the passage of heat. The panel is reinforced internally so that it can support a heavy piece of air handling equipment inside the unit such as an air conditioner heat exchanger coil. The panel includes a reservoir for collecting moisture from the coil and rapidly exhausting the moisture from the unit.

Abstract: A panel for use in air conditioning duct for carrying air along an enclosed path of travel. The panel includes a rectangular shaped frame made of a material having a relatively high R value. The frame is closed by a top cover and a bottom cover so that a cavity is established within the panel. The cavity is filled with a curable material that sets inside the panel to bond the walls of the frame together and to bond the covers to the frame. A bulb seal having high insulation characteristics extending along the length of one edge of adjoining panels so that energy transmission is further inhibited.

Abstract: A pipe connecting structure for connecting a pair of sleeve-like pipes integrally in an axial direction by inserting a male side end portion of one of the pair of sleeve-like pipes into an opening of a female side end portion of the other sleeve-like pipe so as to serve as a connecting portion, wherein a male side protrusion insertion hole and a female side protrusion insertion hole are formed in a peripheral surface of each end portion of a pair of the sleeve-like pipes which constitute the connecting portion, the protrusion insertion holes are brought into coincident with each other, an engagement protrusion is inserted in the protrusion insertion holes and engaged therewith, and such an engagement state of the engagement protrusion is retained by pressing the engagement protrusion with a sleeve member disposed in such a manner as to cover the connecting portion.

Abstract: An electrically self-grounding connector for joining end portions of fluid flow conduit sections, and two processes for fabricating the connector. A connector formed according to one process includes an inner layer formed by electrically conductive, contiguous carbon ribbons, an outer layer of chopped carbon fibers, and a layer of surfacing veil between the inner and outer layers. A connector formed according to the other process substitutes a layer of carbon cloth for the carbon ribbons. In both connectors, electrically conductive carbon forming the inner and outer surfaces acts to dissipate and neutralize electrostatic charges generated by triboelectric processes.

Abstract: An accessory to be attached to a base section of trunking for routing electrical cables is provided with a wall for concealing, inside the trunking, any longitudinal gap beyond an edge of at least one length of cover section. The wall has an effacable projecting finger on the front. Applications include the fitting of electrical devices.

Abstract: The application describes a method of manufacturing a double-walled pipe structure, comprising the steps of providing a pair of inner flow pipe and an outer sleeve pipe around each thereof, providing an insulating material within each annular space therebetween, joining the two inner flow pipes in an end-to-end relationship with the outer sleeve pipes spaced apart, and sliding a cover section into place over the gap between the sleeve pipes, the cover section comprising a length of tube with a longitudinal split therealong, wherein prior to sliding, the cover section is opened by enlarging the split thereby to provide an inner diameter greater than the outer diameter of the sleeve pipe, and after sliding the cover section is compressed such that its inner diameter is less than the outer diameter of the sleeve pipe.

Abstract: A panel for use in air conditioning duct for carrying air along an enclosed path of travel. The panel includes a rectangular shaped frame made of a material having a relatively high R value. The frame is closed by a top cover and a bottom cover so that a cavity is established within the panel. The cavity is filled with a curable material that sets inside the panel to bond the walls of the frame together and to bond the covers to the frame. A bulb seal having high insulation characteristics extending along the length of one edge of adjoining panels so that energy transmission is further inhibited.

Abstract: A floor panel for use in an air handling unit that provides a thermal barrier to the passage of heat. The panel is reinforced internally so that it can support a heavy piece of air handling equipment inside the unit such as an air conditioner heat exchanger coil. The panel includes a reservoir for collecting moisture from the coil and rapidly exhausting the moisture from the unit.

Abstract: An insert with connecting outlet for flexible hoses, particularly for hydraulic and industrial applications, comprising a body which is suitable to be inserted, with a first end, in a flexible hose to be connected and, with a second end, in a port of an apparatus, by locking through a rotatable male element; the end of the body of the insert that is suitable to be inserted in the apparatus port being provided with a retention element which is suitable to lock in its seat the rotatable male element when the insert is inserted, with its second end, in the rotatable male element, the rotatable male element being externally threaded for engagement with the port of the apparatus.

Abstract: A pipe bend for a pipeline for transporting abrasive materials, includes a pair of coupling collars having an outer ring, which has an outer circumferential anchoring groove, and an inner ring secured in the outer ring against axial displacement and made of a more wear-resistant material than the outer ring. Extending between the coupling collars is an arcuate outer pipe portion which is welded at both its ends to the outer rings of the coupling collars, and has a greater inner diameter than the outer rings. Extending at a radial distance to the outer pipe portion between the inner rings of the coupling collars is an arcuate inner pipe portion made of more wear-resistant material than the outer pipe portion and having opposite ends of an inner cross section in coaxial alignment to an inner cross section of the inner rings, for radial support upon the outer pipe portion.

Abstract: A modular protective sleeve for underground utilities may be pulled into an underground utility duct by using lanyards extending between two adjacent manholes through the utility duct. The modular protective sleeve may be assembled over an existing and active utility service such as electrical or telephone cables, optical cables, or gas lines, without disrupting the utility service. The protective sleeve comprises at least one bottom half-shell and two top half-shells which are interlocked on to another in such a way that they may be pulled in either direction. Once the protective sleeve is in place, the concrete casing surrounding the utility duct may be broken without danger to the utility service, after which repair or splicing to the utility can be carried out. The sleeve may then be retrieved for re-use, or left in place.

Abstract: In a structure for joining a first plastic part and a second plastic part, the first plastic part is composed of at least one resin such as polyamide (PA), polybutylene terephthalate (PBT), polyacetal (POM), polyethylene terephthalate (PET), or polyphenylene sulfide (PPS), while the second plastic part is composed of high-density polyethylene (HDPE). Between the two parts, a metamorphic polyethylene layer exhibiting a good joining property for both the first and second plastic parts is interposed to join the parts.

Abstract: A hanger comprises a contact portion that makes surface contact with one face of the duct; a tongue piece as an engagement member that protrudes from the contact portion toward a tip end; a base portion bent continuously with the contact portion and away from the duct so as to form a guide rail accommodating space between the base portion and the tongue piece; a pressing portion formed continuously with the base portion, for pressing a face adjacent to the one face toward the tip end of the tongue piece to allow the guide rail to be securely retained between the pressing portion and the tongue piece; and a member for mounting a hanging member to the base portion. A method for hanging the duct comprises inserting a tongue piece of the hanger into the groove-shaped space of the duct; and bending the pressing portion toward the guide rail to press the face adjacent to the one peripheral face of the duct, thereby fixing the hanger to the duct.

Abstract: A coupling for interconnecting two double-walled pipes, e.g. production filter pipes (10, 12). The coupling may have the shape of a connector (10A, 12A) divided into two parts, each part (10A, 12A) being attachable on the end portion of a double pipe (10, 12), the parts (10A, 12A) of the connector being interconnectable, preferably mutually screwable. Such double pipes (10, 12) have two concentric liquid passages, one through the inner pipe (14) and one through the annulus-like, concentric liquid passage 920) between inner pipe (14) and outer pipe (16). In order not to block the outer concentric liquid passage (20) at the joint place (10A, 12A) so that liquid flowing therewithin must be transferred to said smaller pipe through a valve, longitudinally extending, through-going flowing channels (18) have been formed in the joint area; said channels (18) may be distributed circumferentially, thus allowing continuous flow of liquid past the coupling area (10A, 12A).

Abstract: A duct assembly for transporting pressurized fluid therethrough. The assembly includes first and second duct sections. Each of the duct sections has sides extending between opposite ends. Each of the sides join an adjacent side and has a flange extending laterally outward from each end. The first and second sections are positioned in end-to-end relation so that the flanges extending outward from one of the ends of the first section face the flanges extending outward from one of the ends of the second section to define flange pairs. The assembly also includes a plurality of connector pairs. Each of the connector pairs are positioned at one of the ends of the duct sections. Each of the connector pairs includes a first connector spanning adjacent flanges of the first duct section and a second connector spanning adjacent flanges of the second duct section.

Abstract: Girth welds with crack arresting capability, and welding methods for producing same in high strength pipelines, are provided. Girth welds according to this invention are produced in high strength pipelines by welding methods that produce (i) HAZ microstructures that are softer than the pipeline steels, (ii) weld toes that act as stress/strain concentrators, thus promoting tearing in the HAZ and a ring-off fracture; and (iii) a weld geometry that promotes an inclined fracture path.

Abstract: A temporary fixing structure includes recesses formed with a mounting hole of a first tubular body to face each other wherein the diameter of the mounting hole extending along the recesses is smaller than that of a flange, and protrusions arranged at the head of an end portion of a second tubular body wherein a spacing between the protrusion and the flange is substantially equal to the thickness of a mounting surface of the first tubular body and wherein the protrusions are arranged inside the fist tubular body through the recesses. The second tubular body is turned with respect to the first tubular body to bring a flat portion of the flange into close contact with the mounting surface of the first tubular body.

Abstract: A flexible raceway arrangement for routing power and/or communication cabling to a work area. The raceway arrangement includes an elongate support member which mounts thereon a plurality of raceway covers arranged along the support member in side-by-side relation with one another to define an elongate raceway run. The individual side covers are pivotably openable to provide access to cabling within the interior thereof.

Abstract: A device for tightening a spout, attached to a previously installed angled pipe having an outside radius of curvature, in a position relative to a stop member having an opening through which at least a length of the pipe extends, comprising, at least one sleeve, comprises: at least a first leg and a second leg which meet at a juncture which defines an angle substantially corresponding to the angled pipe, wherein the first and second legs have a combined total length, wherein the first leg has a leg length and is substantially rigid along at least a portion of the leg length, has an inside radius of curvature that is approximately equal to or greater than the radius of curvature of the angled pipe, and wherein the sleeve has a slit, along the entire total length of the first and second legs, to allow the sleeve to be pressed onto and at least partially about the angled pipe; and a method for using the same.

Abstract: A bead and interconnecting bead structure for use in a flexible arm assembly having improved interface characteristics allowing for simple, quiet adjustment of the structure in three dimensions, while simultaneously increasing the weight of object the arm assembly can support. The interface characteristics are improved by utilizing two different materials at the area of contact between two adjacent beads.

Abstract: A pipe construction kit comprises two pipe sections in the form of twin-wall pipes. A spigot is formed on one end of a pipe section, while a socket is formed on the associated end of the other pipe section. The socket and the spigot are twin-wall pipes, having predominantly smooth-walled internal pipe sections and corrugated external pipe sections with elevations and troughs. The outside diameter of the pipe sections and the outside diameter of the socket are approximately equal.

Abstract: The disclosure relates to a plastic jacket having air spaces formed by spaced walls used to insulate hot and cold piping systems and the fittings for those systems. The jacket is made from multiple segments, which are joined together along their longitudinal joints. The segments are joined to each other by tongue and groove connections. One segment can be cut longitudinally and glued to another segment to make a larger segment to fit various diameters of pipe. In a further embodiment, the plastic jacket is modified to form the duct of a heating, ventilating and air conditioning system. The inner wall of the jacket forms the air duct. In both embodiments, at least some of the segments have hinge portions created by omitting the inner wall at the hinge portions.

Abstract: The invention relates to an improved system for connecting the ends of sheet metal ducts wherein each duct end is provided with a double walled frame. Corner connectors defining perpendicularly extending arms are associated with each frame, and bolts or other fasteners are utilized for connecting the connectors and frames. The respective double walled frames comprise integral sections at the duct ends. The sections include an upturned portion extending perpendicularly outwardly from the duct wall, a second portion bent rearwardly from the outer end of the first portion, a third return portion, and an inner wall portion extending from the outer end of the third portion and forming a L-shaped portion. When the frame is formed in this fashion, it is adapted to receive the side edges of respective arms of corner connectors whereby the ducts may be efficiently assembled by locating corner connectors in place and thereafter applying the fasteners used for maintaining the assembly.

Abstract: The invention relates to an improved system for connecting the ends of sheet metal ducts wherein each duct end is provided with a double walled frame. Corner connectors defining perpendicularly extending arms are associated with each frame, and bolts or other fasteners are utilized for connecting the connectors and frames. The respective double walled frames comprise integral sections at the duct ends. The sections include an upturned portion extending perpendicularly outwardly from the duct wall, a second portion bent rearwardly from the outer end of the first portion, a third return portion, and an inner wall portion extending from the outer end of the third portion and forming a L-shaped portion. When the frame is formed in this fashion, it is adapted to receive the side edges of respective arms of corner connectors whereby the ducts may be efficiently assembled by locating corner connectors in place and thereafter applying the fasteners used for maintaining the assembly.

Abstract: A removable/reusable insulating cover includes an insulating material, a flexible and puncture resistant coating, a flap which is an extension of the coating and a hinge which is an integral part of the coating. The system provides a flexible yet durable insulation cover, which may be removed and reused.

Abstract: A bendable tube used for an endoscope or the like, includes a plurality of joint pieces 11 arranged in a row. Each of the joint pieces is provided at one end portion thereof with a pair of first connecting portions 12 and at the other end portion with a pair of second connecting portions 13. The first connecting portions 12 are projected in a center axis direction of the joint piece and arranged 180 degrees away from each other in a peripheral direction, and the second connecting portions 13 are projected in the opposite direction to the first connecting portions 12 and arranged 180 degrees away from each other in the peripheral direction. The first connecting portion 12 is formed with a through-hole 12a (retaining portion) and the second connecting portion 13 is formed with a protrusion 13a. The first and second connecting portions 12, 13 of the adjacent joint pieces 11 are connected together only by fitting engagement between the protrusion 13a and the through-hole 12a.

Abstract: The present invention provides a metal pipe bonded body formed from a plurality of metal pipes. Each metal-pipe is formed with an elongated, pre-formed portion at each end, and a central portion, each elongated, preformed portion having a constant inside diameter greater than an inside diameter of the central portion of each metal pipe.

Abstract: Three embodiments of an expandable screen are described. In the preferred embodiment, the base layer, filtering layer, and outer layer are joined together in a sintering furnace in the form of a flat sheet which is in turn rolled up. The layered sheet is then formed into a tube by rolling it to make a longitudinal or spiral joint which is welded with connections placed on ends. In an alternative embodiment, the base layer and filtering layer are sintered together and formed into a tube which is in turn inserted into an outer protective tube. In a third embodiment, a base pipe is perforated and its exterior surface threaded. A wire runs through the threads with a protective jacket over the underlying assembly. Upon expansion, the opening sizes remain relatively constant.

Abstract: Pipes or pipelines insulated on their surface or surfaces are described. The pipes or pipelines may be for submerged service, below the surface of water. The insulation chosen may be an epoxy substantially free of phenolics and one or more of glass or ceramics. The coating may be an abrasion resistant coating. Such pipes or pipelines are generally intended for the transport of fluids, which can include natural gas, natural gas liquids, crude oil, refined products, chemicals, combinations thereof, and the like.

Abstract: A conduit pipe is installed within a cable tunnel and telecommunication cables are disposed in the conduit pipe. The conduit pipe is divided longitudinally into a plurality of divided bodies. Each divided body is equipped at one longitudinal side with a retaining part and at the other longitudinal side with a protruded part. A single conduit pipe is formed when the divided bodies are connected to each other along the longitudinal side. Since the divided bodies can be wound around a small-diameter bobbin to be carried, the space for their custody is reduced and the carriage thereof is easier. Further, since connection parts on surfaces of the conduit pipes can be arranged such that they occupy empty spaces between conduit pipes, the space occupied by the connection parts can be minimized, thereby comparatively larger number of telecommunication cables being able to be disposed within the cable tunnel.

Abstract: Pipes or pipelines insulated and optionally coated on their interior surface or surfaces are described. Pipes or pipelines insulated and optionally coated on their exterior surface or surfaces are also contemplated, The pipes or pipelines may be for submerged service, below the surface of water. The insulation chosen may be an epoxy substantially free of phenolics and one or more of glass or ceramics. The coating may be an abrasion resistant coating. Such pipes or pipelines are generally intended for the transport of fluids, which can include natural gas, natural gas liquids, crude oil, refined products, chemicals, combinations thereof, and the like.

Abstract: This invention relates to a co-tube assembly for a heating and air conditioning system. The co-tube assembly comprises a connector an inner tube and an outer tube. The connector including a first opening, a second opening and a third opening. The inner tube extends through the first opening and the second opening of the connector. The inner tube has a first portion axially outwardly of the first opening of the connector and a second portion axially outwardly of the second opening of the connector. The outer tube is disposed over the first portion of said inner tube and inserted into said first opening of the connector.

Abstract: A conduit pipe is installed within a cable tunnel and telecommunication cables are disposed in the conduit pipe. The conduit pipe is divided longitudinally into a plurality of divided bodies. Each divided body is equipped at one longitudinal side with a retaining part and at the other longitudinal side with a protruded part. A single conduit pipe is formed when the divided bodies are connected to each other along the longitudinal side. Since the divided bodies can be wound around a small-diameter bobbin to be carried, the space for their custody is reduced and the carriage thereof is easier. Further, since connection parts on surfaces of the conduit pipes can be arranged such that they occupy empty spaces between conduit pipes, the space occupied by the connection parts can be minimized, thereby comparatively larger number of telecommunication cables being able to be disposed within the cable tunnel.

Abstract: The invention relates to an article of manufacture comprising a partial or complete tubular primary part defining a tube axis and having an at least partially curved circumferential wall at least partially encircling the axis; said wall comprising a joint edge, defining a) a joint line along said edge on said wall, b) a joint plane drawn to contain said joint line, c) a joining direction having at least a direction component perpendicular to said joint line and said joint plane, d) a locking plane at least partially at the surface or within a section through said wall in which both said joint line and said joining direction lies and e) a normal direction being perpendicular to said joint plane; and at least one locking structure, the improvement comprising that the locking structure includes at least one positive or negative hook structure in said locking plane, extending in the joining direction away from the joint line and having an undercut in the locking plane and that the hook structure is exposed from a

Abstract: Thermal insulating panels for application to HVAC rectangular ductwork each comprise a first layer of solid insulation with a second layer of solid insulation laminated to the first layer. An outer metal layer of embossed aluminum is laminated to the second layer of each panel. These panels are secured to the outside of the rectangular ductwork with at least four interlocking panels, one on each side thereof joined together at the four corners of the ductwork. The outside metal layer of embossed aluminum of at least some of the panels includes right angle flanges along the sides thereof for attachment to an adjacent panel. A number of panels are arranged end-to-end in a series along each side of the rectangular duct, and an overlapping joint is provided between adjacent panels in the series.

Abstract: A first strand of interconnected hollow polymeric chambers is connected to a second strand of interconnected hollow polymeric chambers. A connecting portion of the first strand has an outer surface contour conforming to a portion of the inner surface of a chamber. A partial chamber is formed on the end of the second strand, the partial chamber having an inner surface that conforms to the outer surface of the connecting portion. The connecting portion is inserted into the partial chamber and the two strands are held together by adhesive.

Abstract: A pipe bend for a pipeline for transporting abrasive materials, includes a pair of coupling collars having an outer ring, which has an outer circumferential anchoring groove, and an inner ring secured in the outer ring against axial displacement and made of a more wear-resistant material than the outer ring. Extending between the coupling collars is an arcuate outer pipe portion which is welded at both its ends to the outer rings of the coupling collars, and has a greater inner diameter than the outer rings. Extending at a radial distance to the outer pipe portion between the inner rings of the coupling collars is an arcuate inner pipe portion made of more wear-resistant material than the outer pipe portion and having opposite ends of an inner cross section in coaxial alignment to an inner cross section of the inner rings, for radial support upon the outer pipe portion.

Abstract: A transport pipe for solid materials has a single layer pipe section having a threaded first end and a thread second end. The pipe section has a hardened inner mantle. A first coupling collar having a first threaded collar is threaded onto the threaded first end. A second coupling collar having a second threaded collar portion is threaded onto the threaded second end. Wear-resistant layers are located in the region of the first and second coupling collars.