JPH033832B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for joining threadless metal tubes. More particularly, the present invention relates to a method and apparatus for joining and assembling lined conduits by an interference fit to form a continuous lined conduit, and to fittings formed by such methods.

Various methods are used to join the tubes to form a continuous conduit. The most common tube joining method joins the male threaded tube end of one tube section to the female threaded box end of another tube section. This interconnection is commonly referred to as a joint, and in the case of a threaded end, a threaded joint.

Although satisfactory for many applications, threaded pipe fittings are relatively expensive to manufacture and require considerable time to join. For example, joining two threaded pipes requires turning at least one of them, but joining two relatively long pipes with regular threaded ends is difficult, if not impossible. .

Other joining methods such as welding are commonly used to join pipes. However, in many applications it is necessary to provide a protective lining on all interior surfaces of the conduit. Each inner surface is made of a material such as polyvinyl chloride or polyester resin that adheres to the inner surface of the tube as described in U.S. Pat. No. 3,758,361 to John J. Hunter. They are best protected by linings made of other lining materials. When the inner surface of a conduit is protected by such a lining (in this case referred to as a plastic lining), a piece is provided that joins each lining to one another at the junction of two pipes, so that the lining is continuous and forms a conduit. All internal surfaces shall be lined continuously. Welding generally cannot be used to join each lined tube because the heat required to weld the tube ends together will cause the plastic lining to melt and separate from the tube wall as the tubes are welded.

Various types of threadless fittings have been considered for forming conduits where the pressure of the fluid being directed through the pipe is relatively low. A threadless joint is formed, for example, by widening the inside diameter of one end of a tube section to a diameter that is slightly smaller than the outside diameter of the tube. This flared end is commonly referred to as a bowl. The ends of adjacent tubes that fit within this bowl are commonly referred to as pin ends or pistons. Suitably, the bowl is made by pushing a mandrel of the desired shape into one end of the tube to form a bowl of enlarged dimensions with a flared end, and inserting the pin end into the flared section. It can be pushed into the rest of the bowl. Such a joint is
Referred to as interference fit fittings, they are generally used when the pressure of the fluid flowing through the conduit is relatively low. For example, this interference fit joint is used in automobile exhaust pipes and the like. Since the inside diameter of the bowl is smaller than the outside diameter of the pin, the bowl must bulge slightly radially upon axial insertion of the pin therein. The difference in diameter is commonly known as interference, and the friction between the tightly fitted walls creates a bonding force.

One of the major advantages of interference fit joints is that they are relatively quick and inexpensive to form and do not require turning the pipe sections to form the joint. Furthermore, since excessive heat is not required to form an interference fit, the plastic-lined pipe sections can be formed with appropriately constructed ends that mate or overlap the plastic liner to some extent to form a well-lined conduit upon assembly. do. Among the disadvantages of common interference fit joints is that the joints are usually unable to withstand high pressures and may leak or separate when subjected to high internal pressures.

Various methods of joining the ends of lined tubes are available to form a well-lined conduit. However, in many cases each end of a lined tube is specifically provided with a lining extending from one end of the tube in a particular configuration, such that when these specially constructed ends are joined together, a fully lined conduit is created. It is designed to form a If the liner is a tubular liner inserted into and glued to the tube, the liner should extend appropriately from the end of the tube so that the overlapping ends of the liner are an interference fit between each tube section. When joined together by a method, they form a well-lined conduit. However, if the lining is formed, for example, by spraying a coating onto the inner surface of the tube, it has not heretofore been possible to form a fully lined conduit with an interference fit joint. Furthermore, it is often necessary to remove a portion of the conduit formed from the lined tube section, replace a damaged or defective section, or connect this conduit to another conduit by means of a T-joint or the like. When making such repairs or replacements, the tube section must be cut and its open end joined to another tube section or other conduit.

However, when cutting a plastic lined tube, the end surface of the metal tube is exposed. Therefore, special care must be taken to protect the exposed end faces of the tubes.
This exposed end is in fluid communication with the interior of the conduit when the conduit is rejoined.

Conventional flanges cannot be welded directly to thin-walled tubes with plastic linings because the heat generated by the welding process usually destroys the lining. Furthermore, the tubes are often of thin walled construction such that they cannot be threaded to attach flanges or nipples. Other joining means are therefore required.

Conventional interference fit joints cannot be formed because the conduit is lined. However, according to the present invention, the interference fit joint can be made either thick-walled or thin-walled by using a connecting sleeve that joins each end of the lined pipe and a special piece within this sleeve that protects the end face of the metal pipe. It can also be formed into lined pipes.

Claims 1, 4, 6, 1
According to each invention described in paragraphs 1 and 18,
Since threaded pipe sections are not used, it is possible to connect pipe sections with thin pipe walls, and it is also possible to connect pipe sections that cannot be rotated, thus making it possible to connect pipe sections. This can be done at low cost and in a reduced amount of time, and an inexpensive continuous joint can be obtained.

According to the inventions set forth in claims 6 and 11, as is clear from FIGS. According to the inventions described in Items 1, 4, and 18, the following other effects can be obtained.

Furthermore, according to the invention set forth in claim 1, as is clear from FIG. In order to keep track of section 5,
In the connecting joint in which 0 and 52 are directly connected by interference fit, the inner lining 51 is not damaged.

Furthermore, according to the invention described in claim 4, as is clear from FIG.
Since the pipes are inserted in a telescopic manner until they are mated, the two pipe sections can be directly connected by interference fit without damaging the lining 51.

Furthermore, according to the invention set forth in claim 18, as is clear from FIG. A plastic-to-plastic seal is obtained.

The present invention provides a method and apparatus for joining the ends of two lined intermetallic sections such that the lined ends and metal tube end faces are substantially adjacent to form a continuous, fully lined conduit. . The end face of each metal tube section is protected by a plastic collar that is inserted into the open end of the lined tube and has a radially extending flange over the end of the metal tube. These flanged collars push each other into a coupling sleeve that joins the two pipe sections together with an interference fit. A strip of plastic lining is transferred into the annular recess of the coupling sleeve to substantially line the mating conduit at the radial edge of the flanged plastic collar. Each end of the sleeve is then pushed into the tube to form a mechanical assembly. The ends of the tube sections are thus joined together to form a connection which provides a well-lined conduit. Additionally, the fitting can be conveniently and quickly formed without applying sufficient heat to damage the lined tube. The interconnections may also be mechanically interlocked sufficiently to withstand the internal pressures endured by the remainder of the conduit.

The interconnection method of the present invention is typically used in the field of repairing or modifying existing lined conduits since it does not require turning the pipe to form the joint. In one version of the invention, a plastic collar is inserted into the pin end of the lined tube and used to complete the fully lined joint with the bowl-shaped end of another suitably coated tube section. Accordingly, the present invention provides a means for joining spray coated lined tubes by an interference fit method to form a fully lined joint.

Various methods are well known in the art for forming a continuous lined conduit by joining the ends of each lined tube section. Metal tubing sections with a continuous tubular plastic lining, typically polyvinyl chloride or other plastic material, are formed such that the plastic lining extends from the end of the tubing section and overlaps within the fitting, or each plastic lining is in some other manner such that the ends of the tubes are joined together to form a continuous lined conduit.

When excluding one section of such lined conduit,
Such removal is usually accomplished by simply cutting the tube. Pipes may be cut for several reasons, such as to remove defects, damaged or leaking sections, or to install T-joints or other devices. However, when a portion of the conduit is removed, such as by sawing or similar operation, the tube and lining are cut together in the same plane, leaving an open end. In this way, the end face of the tube is exposed and not covered with a lining. In order to rejoin each tube section or to join a tube section to another conduit, steps must be taken to protect the exposed end surfaces of the tubes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a connecting joint, a method between metal pipe sections, and an interference fit connecting joint according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the mutually opposing ends of two tube sections. In FIG. 1, the tube lining and metal tube are of the same length. These tube sections are joined together to form a continuous lined conduit. The first one has a plastic lining 11 as shown.
The tube section 10 is adapted to be joined to a second tube section 12 having a plastic lining 13.
Each metal tube section 10, 12 has a respective lining 1
Exposed end faces 14, 1 that lie within the plane of the end faces of 1, 13
Has 5. Each end face 14, 15 is protected and each pipe section 1
An end collar 30 is positioned within the open end of tube section 10 so that the ends of tube section 10 join to form a continuous lined conduit. As shown in FIG. 3, it has a cylindrical body 31 with an open end flange 30. The external dimensions of the cylindrical body 31 are the pipe section 10.
It almost matches the internal dimensions of the inner lining 11. End collar 30 includes a radially extending flange 32 extending radially outwardly from the end of cylinder 31 to mate with exposed end surface 14 of tube section 10, as shown in FIG. The end collar 30 is preferably made of the same material as the lining 11. The end collar 30 can thus be glued to the lining 11 with a solvent such as methyl ethyl ketone or any suitable conventional epoxy adhesive or the like that is compatible with the materials used.
The flange 32 extends radially outwardly enough to at least completely cover the exposed end surface of the tube section 10 and has an outer diameter that is 0.015 inches greater than the outer diameter of the tube section 10.

The same collar 3 in the open end of the second tube section 12
0 is similarly positioned.

The end of each pipe section 10, 12 is connected to a connecting sleeve 20.
be placed coaxially with the The connecting sleeve 20 is a relatively short section of metal tubing having an inner diameter slightly smaller than the outer diameter of the end of each tube section 10,12.
In the preferred embodiment, the inner diameter of the connecting sleeve 20 is approximately 0.060 inches greater than the outer diameter of the end of each tube section 10,12.
(about 1.524 mm) smaller. The difference between the inner and outer diameters is known as the interference and is determined by the dimensions of the tube, the thickness of the tube wall, the tube material, the axial interference length, and other factors, as is known in the art. It changes over time. The open ends 23, 24 of the coupling sleeve 20 are preferably flared outwardly as shown in FIG. 1 to facilitate insertion of the open tube section ends therein.

In the preferred embodiment, the connecting sleeve 20 is formed with a generally centrally located annular depression 21 or groove in which the sealing strip 22 is supported. The sealing strip 22 is preferably of the same material as the lining 11 and the end collar 30. Sealing strip 22 may be glued or secured within recess 21 with a suitable epoxy adhesive or the like. The inner diameter of the sealing strip 22 is at least the same as the inner diameter of the remainder of the coupling sleeve 20 and about 0.005 to about 0.015 inches (about 0.127 to about 0.381 millimeters) less than the inner diameter of the coupling sleeve 20.
It is only necessary to have a smaller inner diameter.

The coupling joint according to the invention is formed by pushing the open ends of each section 10, 12 with end collars 30 into the opposite open ends of the coupling sleeve 20, either simultaneously or separately, as will be described below.

To ensure a uniform and stable joint, the ends of each tube section 10, 12 may be cleaned and sized prior to assembly. The outer diameter of the tube section varies slightly between manufacturers, and the cross section of the tube section is often not perfectly circular. This is especially true if the conduit has been previously used. Furthermore, buried or exposed conduits may have corrosion on their exterior surfaces. Therefore, to prepare the ends for an interference fit connection, each end is cleaned by conventional means to remove scale, corrosion and the like, and sized by passing a circular sizing collar around it. stipulate. Sizing each end to the desired outside diameter prior to assembly is such as to avoid rubbing or the like which would be detrimental to obtaining the desired interference and forming a satisfactory interference fit joint.

If desired, the flange 32 may be removed immediately before assembly of the joint.
A suitable solvent or adhesive may be applied to the flange 32 to bond the opposing surfaces of the flange 32, each flange edge, and the sealing strip 22 in a sealed state.

When forming an interference fit joint, the pin end of the tube section is optionally lubricated to facilitate insertion of the pin end into the dowel. When using common lubricants, avoid mixing the lubricant with common plastic adhesives, such as PVC glue and similar, as the lubricant will interfere with the formation of joints between each plastic material part. You must be careful.

The preferred embodiment of the invention uses an epoxy resin both as a lubricant and to facilitate forming a metal-to-metal joint between the tube section ends and the connecting sleeve 20. In this case, any suitable common adhesive may be used. Two-part epoxies have been found to be particularly suitable for forming metal-to-metal seals. A suitable epoxy resin is manufactured by Cooks Paint & Burnish Company, Kansas City, Missouri, USA.
Varnish Company) with the product name Steal・
Steel Seam is a metal adhesive sold commercially as Steel Seam. This adhesive is applied to the base (product name
920W979) and a hardener (commercially available as 920L927). The hardener and substrate are mixed immediately prior to use and applied to the outer surface of each tube end immediately prior to insertion of each tube end into the connecting sleeve 20. Care must be taken to avoid mixing the metal-to-metal adhesive with the PVC adhesive or solvent used to bond each plastic part. However, the particular two-part epoxy described above can be used in metal joints with adhesive PVC sections. Do not use PVC glue in this case. Instead, a two-part epoxy is applied to each plastic section and each tube end prior to insertion of each tube section into the connecting sleeve 20. The resulting plastic-to-plastic seal is
Although it does not have the qualities obtained with PVC adhesives, it has been found to be suitable for many applications. The single use of this epoxy thus serves as a lubricant, metal-to-metal adhesive and plastic-to-plastic adhesive to eliminate contamination problems.

A variety of industrially available devices may be used to force each tube end into the connecting sleeve 20. For example, using a common tube press or the like. In the preferred embodiment, the connecting sleeve 20 is held stationary and one tube end is inserted into the sleeve 20 until the leading edge of the flange 32 is approximately centered within the sealing strip 22. The other tube end is then pushed into the opposing end of the connecting sleeve 20 until the opposing flanges 32 meet in abutting relationship within the sealing strip 22.

The finished joint is illustrated in FIG. It will be appreciated that the mutually opposing surfaces of each flange 32 mate in sealing relation and the respective outer edges mate with sealing strip 22 to form a sealing connection. Each flange 32 is held together by end faces 14, 15 of the tube ends which are fully contained within the plastic material. In this way a conduit is formed which is fully lined with plastic material. However, structural rigidity is maintained by the interference fit between each tube end and the connecting sleeve 20. To lock each end of the tube into a fixed relationship,
The widened ends 23, 24 of the connecting sleeve 20 are then compressed radially into the tube sections 10, 11, respectively.

The radial compression of each end of the sleeve 20 to form a crimped combination can be accomplished in a variety of ways. Any device that deforms a portion of sleeve 20 may be used. In the preferred embodiment, this is accomplished by partially pushing a bending collar axially around the end of sleeve 20 after forming the interference fit joint. The bending collar has an inner diameter that tapers from a diameter slightly greater than the outer diameter of the tube to an inner diameter that is greater than the outer diameter of the flared portion of the sleeve 20.
The flared constriction collar widens the inner diameter of the collar toward the sleeve 20 around the tube. After forming the interference fit joint, the bending collar is moved axially around the tube and associated with the flared end of the sleeve 20. Since the folded collar expands internally and completely surrounds the tube, the end of the sleeve 20 is uniformly radially compressed and forced into the tube to form the groove 25. That is, the end of the sleeve 20 is permanently deformed and grooved 2.
5 to form a connecting joint as shown in FIG.

A combination of bends is formed by uniformly radially compressing the entire 360° around the end of the sleeve, although a full 360° bending is not necessarily required. Any portion of the sleeve may be bent and shortened to combine tube sections without departing from the principles of the present invention. However, when using internal bending contractions of less than 360°, the degree of mechanical integration is proportionally reduced.

Although the present invention has been specifically described with respect to bending and crimping the mouth end of the sleeve by forcing a crimping ring around it, other means may be used to apply a radial compressive action to the mouth or other portions of the sleeve. It is obvious that it can be used. A similar build-up can be achieved, for example, by using circumferentially rotating inward compression rollers to bend the opening of the sleeve into the tube. When the opening of the sleeve is bent to form a bent portion, a uniform radial compression action is not applied to the opening, making it impossible to obtain a uniformly bent joint. However, the use of circumferential radial compression rollers allows the sleeve 20 to be deformed at locations other than its ends. For example, circumferential radial rollers may be used to form one or more grooves or groove portions at various locations along the length of the sleeve 20 to form similar mechanical combinations.

The interconnection methods and devices described above also apply to conduits where the lining is a tubular lining bonded to the inner surface of the tube, and where a fluid lining material is sprayed or otherwise applied to the interior of the tube to form the lining. The same applies to spray-coated linings formed on-site. However, formed-in-place linings are typically thinner than bonded tubular linings, and grooves 25
It may break during forming due to compression of the open end of the 0. Obviously, a well-lined conduit will not be obtained if the lining is damaged, cracked or peeled off by the bending operation. In a preferred embodiment of the invention, the tubular body 3 of the end collar 30
1 must have sufficient axial length to extend past the groove 25 formed by the bending operation. A tubular body 31 is glued to the inner lining 11 and grooves 2 are formed.
5, the tubular body 31 extends past the groove 25.
Only slight deformation occurs in the lining 11 so that the well-lined conduit is retained without separation from the lining 11.

Because the end faces 14, 15 of each tube section 10, 12 narrow exactly 90 DEG to the longitudinal axis of those tube sections, the opposing flanges 32 do not abut fully when the joint is assembled. The sleeve 20 is therefore provided with a sealing strip 22 as described above. Therefore, even if there is a partial gap between the flanges 32 in the finished joint, the fluid entering this gap will come into contact with the sealing band 22 as long as the end of each pipe section is within the sealing band 22 of the finished fitting. Just do it.

If a relatively thick material is used for the connecting sleeve 20, the recess 21 is formed by cutting a centrally located annular recess into the inner surface of the sleeve 20. A sealing strip 22 of the desired material with suitable dimensions is then secured within the recess 21.
The sealing strip 22 can of course be a pre-cut piece of material, or it can be formed in the recess 21 in situ. Alternatively, if a reduction in the wall thickness of the sleeve 20 due to the formation of grooves is undesirable, a pre-cut sealing strip of the required dimensions is positioned as shown in FIG. 4A and preferably glued into the sleeve 20. do it. Next, the sleeve 20 is sealed with the sealing strip 22.
Shrinking the sleeve 20 to the desired dimensions by reducing the inner and outer diameters on both sides, placing the sealing strip 22 in the recess 21 with the original diameter of the sleeve 20, is carried out as described above for the tube ends. This is done by pressing a sizing ring around the sleeve 20. In each case, the coupling sleeve is constructed of a suitably sized material and has an inner diameter smaller than the outer diameter of the tubes to be joined by the sleeve and is shaped to receive a substantially centrally located sealing strip within the sleeve. .

The coupling coupling described above is particularly suitable as a repair coupling for coupling open ends of installed conduits in the field. Although this joint has been described in particular in the case where identical open pipe ends are joined together to form a continuous conduit, the principle of the present invention is that when a connecting sleeve is suitably made, one open pipe end The same applies to joining one section to another conduit. For example, a connecting sleeve can be formed by combining a sealing strip with each collar having a different outer diameter and connecting pipe sections having different outer diameters. Each side has a different inner diameter. Similarly, the connecting sleeve 20 may be an integral part of another conduit section, valve, tee or the like. In this case, the sealing strip forms the inner lining or is previously glued to this lining. Similarly, although the present description has been described with reference to the use of PVC linings or the like, it is understood that the principles of the invention are equally applicable to other types of linings, including lining materials formed in situ within conduits by spraying or similar operations. it is obvious. Additionally, although the invention described above is particularly useful for making repair joints for installed lined conduits, its principles are equally applicable to joining sections of lined conduits to form lined conduits.

One variation of the invention is shown in FIG. 5 in which an end collar 30 is used to cover the end face of a tube section 50 to form a fully lined joint between two tube sections joined by an interference fit. As noted above, conventional interference fit fittings cannot be formed to join two spray coated lined tubes together to provide a fully lined conduit. This is because the pin end of the tube is uncoated or the tube coating is so thin or weak that it can be damaged by insertion of the pin into the bowl. According to the present invention, one end of the tube section 52 is widened to form a bowl-shaped portion 54 having an inner diameter slightly smaller than the pin end of the tube section 50. The bowl 54 thus forms a tapered throat 55 in the tube section 52.
Connect by. The field-formed coating 51 is applied to pipe sections 50, 52 by conventional means such as spraying or the like.
Formed on the inner surface of. The covering of the pin end 50 thus extends only to the end face of the tube, or may actually cover all or part of the upper end face. However, the coatings thus formed in the field are brittle and cannot withstand interference fit connections. The coating of the bowl end extends at least through the throat 55 but does not extend substantially into the bowl 54. Covering 51 extending into a bowl shape 54
is scraped off the surface of the metal tube by the pin end when forming an interference fit joint, and becomes a hindrance to forming an interference fit joint.

To form a fully lined joint, the end collar 30 as described above is located within the pin end of the tube section 50 and the radially extending flange 32 covers the end face of the pin end 50. End collar 30
The tubular body 31 is inserted into the tubular section 5 well past the place where the groove is formed when the mouth of the bowl-shaped portion 54 is deformed.
0 and adhere the inner lining 11. These are all as described above. The pin end 50 then engages and overlaps the leading edge of the jacket lining 51 in the throat 55 with the flange 32 on the end face of the pin. As described above, the pin end of the tube section 50 and the flange 32
Prior to insertion into the throat 54, an adhesive coating is applied to allow the flange 32 to be bonded directly to the lining 51 of the throat 55. A metal-to-metal interference fit connection is thus formed between the pin end 50 and the dowel 54, as well as the lining 5 of the tube section 52.
1 and an end collar 30 forming a continuous lined conduit, a bonded plastic-to-plastic seal is formed. The mouth 56 of the bowl 54 is then deformed radially inward to form a groove 57 as described above and assembled into the groove 57 to form an assembled interference fit joint. Tubular body 3 with end collar 30
1 extends past the mouth 56 of the bowl 54 and the tube section 50
Since the inner lining 51 of the tubular body 3 is bonded to the inner lining 51 of the tubular body 3, damage or displacement of the inner lining 51 due to the formation of the groove 57 will be avoided.
A fully lined joint is obtained which is covered by 1.

To form an elongated overlap of the plastic lining within the joint, the end collar 30 is modified as shown in FIGS. 6 and 7. In the modified end collar 30 shown in FIGS. 6 and 7, the radially extending flange 32 is extended axially and reversely bent and tapered inwardly, as shown by section 32A. The inwardly tapered extension 32A thus mates over the lining 51 within the throat 55 of the bowl 54. The overlapping extensions 32A are thus bonded directly to the liner 51 in the extended overlap region to form a more effective plastic-to-plastic bond in the joint and to form a more effective liner joint. In all other respects the joint formed as shown in FIG. 7 is the same as the joint formed as shown in FIG.

It is clear from the foregoing that the above-described fittings can be formed using various types of linings for repair fittings, modification fittings, or for installation fittings on pipes provided with field-formed linings. can.

Although the present invention has been described above in detail with reference to its embodiments, it goes without saying that the present embodiments can be modified in various ways without departing from the spirit of the invention.

[Brief explanation of drawings]

FIG. 1 is an axial cross-sectional view showing the end portions of two lined pipe sections and one embodiment of the connecting sleeve of the present invention prior to assembly, and FIG. FIG. 3 is an axial sectional view of the formed connecting joint of the present invention, and FIG. 3 is an enlarged perspective view of the end face flange at the end of the pipe section shown in FIG. FIG. 4A is an axial cross-sectional view of another embodiment of the connecting sleeve of the present invention before being reduced to accommodate the sealing strip; FIG.
FIG. 3 is an axial sectional view of the illustrated coupling sleeve after its diameter has been reduced to accommodate the sealing strip; Fig. 5 is an axial cross-sectional view of another embodiment of a connecting joint formed by the joining method of the present invention using spray lined pipes joined by interference fit, and Fig. 6 shows the bowl-shaped end of the lined pipe and pins. FIG. 7 is a perspective view of the end collar used for joining the ends, and FIG. 7 is an axial sectional view of another embodiment of the connecting joint of the present invention formed using the end collar of FIG. 10, 12... Pipe section, 11, 13... Lining, 14, 15... End face, 20... Connection sleeve, 21... Hollow, 22... Band-shaped body, 30...
End collar, 31... tubular body, 32... flange.

Claims (1)

[Scope of Claims] 1. (a) A first tube piece provided with a plastic lining on its inner surface and having an end surface that substantially coexists with an end surface of the plastic lining; a plastic tubular body having an outer diameter substantially matching the inner diameter of the plastic lining of the first tube section; and a radially extending flange disposed at one end of the plastic tubular body. (c) an end collar with the radially extending flange adjacent to the end surface of the first tube section and located within the open end of the first tube section; a second tube section having an open end with an inner diameter smaller than the outer diameter of the section and having a plastics lining on the inner surface, the plastics lining end of the second tube section having an open end with an inner diameter smaller than the outer diameter of the section; terminating within a second tube section remote from the open end thereof, the end of the first tube section being nested within the open end of the second tube section; A coupling joint for interconnecting two metal tubes of suitable lengths in an interference fit such that the radially extending flange overlaps the plastic lining of the second tube section. 2. The opening of the second tube piece is deformed radially inward to form a groove in the first tube piece, and is connected to the first tube piece. The connecting joint described in item 1. 3. A coupling according to claim 2, wherein said plastic tubular body extends into said first tube section past said groove. 4. In the inter-metal section method in which the open ends of two metal pipe sections, each with a plastic lining glued to its inner surface, are joined together to form a continuous lined conduit, (a) a cylindrical body having external dimensions substantially matching the internal dimensions of the plastic lining, and a flange extending radially from one end of the cylindrical body to mate with an end face of the open end of the metal tube section. (b) inserting a plastic collar comprising a collar of plastic material into the open end of one of the metal tube sections; by telescopically inserting the flange into the open end of the metal tube section until it mates with the lining in this other metal tube section;
A method of connecting metal pipe sections comprising forming an interference fit joint between said two metal-to-metal sections. 5 mechanically deforming each of said metal tube sections by deforming at least a portion of the mouth of said other metal tube section inwardly enough to form a corresponding groove in said one metal tube section; The inter-metal zone method as described in claim 4 of the connected claims. 6 In the metal-to-metal section method in which the open ends of two metal pipe sections, each with a plastic lining bonded to its inner surface, are joined together to form a continuous lined conduit, (a) a cylindrical body having external dimensions substantially matching the internal dimensions of the plastic lining and extending radially from one end of the cylindrical body to mate with an end face of the open end of the metal tube section; (b) before insertion of the open end of each metal tube section, a plastic collar comprising a flange is inserted into the open end of each metal tube section; The respective metal tubes are connected by inserting the open ends of each of the metal tube sections into opposite ends of a coupling sleeve having an inner diameter smaller than the outer diameter until the respective flanges meet in mutually contacting relationship. A metal section-to-section method comprising forming an interference fit between the sections and said connecting sleeve. 7 mechanically interlocking each of the metal tube sections and the coupling sleeve by deforming at least a portion of the coupling sleeve inwardly enough to form a corresponding groove in the metal tube section; The inter-metal zone interconnection method according to claim 6. 8 forming an annular recess in the inner surface of the connecting sleeve, positioning a plastic strip within the recess of the connecting sleeve, and positioning each flange of each plastic collar within the plastic strip; 7. A method of joining metal zones as claimed in claim 6, wherein the metal zones are placed in contacting relationship with each other. 9. Adhesive is applied to the end of each metal tube section and the flange of each plastic collar prior to insertion of the end of each metal tube section into the connecting sleeve. The inter-metal zone method described in Section 6. 10. The inter-metal tube section method according to claim 6, wherein the end of each metal tube section is cleaned and sized prior to insertion of the end of each metal tube section into the connection sleeve. 11. An interference fit connecting joint for interconnecting two sections of metal pipe with plastic linings, comprising: (a) a cylindrical body having an outer surface mating with the inner surface of the lining in the end portion of the plastic lining; a flange extending radially from one end of the cylindrical body and mating with the end face of each of the metal tube sections; (b) a plastic end collar located within the end of each of the metal tube sections; Before assembly of the fitting coupling joint, the fitting is comprised of a cylindrical body having an inner diameter smaller than the outer diameter of each of the metal tube sections, surrounding the open end of the metal tube section, and bringing the end surfaces of the respective end collars into contact with each other. An interference fit connecting joint with a connecting sleeve that maintains the 12 Forming an annular recess located approximately centrally in the inner surface of the connecting sleeve, positioning a plastic strip within the recess, and inserting the mutually contacting end surfaces of the end flanges into the plastic strip. 12. An interference fit connection joint according to claim 11, which is located in a position. 13. At least a portion of the connecting sleeve is pressed inwardly into a corresponding recess of the metal tube section to mechanically connect the connecting sleeve and the metal tube section. The interference fit connection joint described in item 11. 14 Mechanically coupling the coupling sleeve and each of the metal tube sections in a fixed relationship by radially compressing each end of the coupling sleeve to form an annular groove corresponding to each of the metal tube sections; An interference fit connection joint according to claim 11. 15. An interference fit connection joint according to claim 11, wherein said plastic end collar is adhered to said plastic lining and to each other. 16. An interference fit connection joint according to claim 12, wherein the plastic end collars are adhered to the plastic lining, to each other, and to the plastic strip. 17. The connecting joint according to claim 1, wherein the radially extending flange is provided with a substantially axial extension extending from an outer edge thereof. 18 A first metal tube of an appropriate length having a bowl shape at one end, and a second metal tube of an appropriate length having a pin end inserted into the bowl shape in a nested manner,
Prior to assembling the interference fit connection joint that connects each other, in the interference fit connection joint in which the outer diameter of the pin end is larger than the inner diameter of the bowl, (a) the first metal a plastic lining bonded to the inner surface of the tube and terminating in the throat of said bowl;
(b) a plastic lining adhered to the inner surface of the second metal tube and substantially terminating in the plane of the end face of the pin end; and (c) a plastic lining within the pin end of the second metal tube. a plastic tubular body having an outer diameter substantially matching the inner diameter of the lining, and a radially extending flange at one end thereof;
a substantially axially extending portion extending from the outer edge of the flange, the radially extending flange being adjacent to the end surface of the second metal tube, and the axially extending portion of the flange being shaped like the bowl. an end face lining located within the pin end overlying the plastic lining of the throat.