GB2047834A

GB2047834A - Coupling joint and method for plastic lined pipe

Info

Publication number: GB2047834A
Application number: GB8012627A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-04-19
Filing date: 1980-04-17
Publication date: 1980-12-03
Also published as: DE3014158C2; FR2454574A1; CA1137136A; AR224764A1; GB2047834B; IT1143139B; FR2454574B1; IT8048426A0; SG6184G; DE3014158A1

Abstract

A fully lined pipe coupling is formed by forming a plastic lining (14, 15) on the open end face (12) of each of two abutting sections of plastic (11) lined pipe (10) and joining such linings (14, 15). Each plastic end face liner comprises a cylindrical tubular body (14) with a radially extending flange (15) and is bonded to the internal surface of the pipe liner (11) and to the end face of the pipe. A collar (16) having a tapered outer diameter (18) and inwardly projecting means (17) for engaging the pipe is positioned to encircle the end of each pipe. A rigid flange (20) having a central opening with dimensions conforming to the outer dimensions of the collar mates with each collar to provide means for attaching the two collars and two pipes together. <IMAGE>

Description

SPECIFICATION Coupling joint and method for plastic lined pipe This invention relates to methods and apparatus for forming plastic lined junctions in plastic lined pipe or conduit commonly used for handling acids, caustics, salt water and other corrosive fluids. One object is to provide a method and apparatus for joining uncoated ends of plastic lined pipe and coating the end facings of said plastic lined pipe to provide a fully lined conduit joints or sections of lined pipe are joined. in one embodiment thereof, the invention may be used to join sections of lined or un-lined pipe.

Plastic lined pipe has long been used used for conducting acids, caustics, salt water and othercor- rosive or abrasive fluids which cause deterioration of metal pipes.

Frequently it is necessary to remove a portion of a length of plastic lined pipe after the pipe is installed to insert a 'T' or other conduit means or remove and replace a ruptured or faulty pipe section. When such repairs or alterations are made in a pipe string, the pipe must be cut and the open end thereof joined with another pipe or other conduit means.

When the pipe has been cut, the end facing of the metal pipe is exposed. Accordingly, unless special precautions are taken to protect the exposed end facing of the pipe, the exposed end will be in fluid communication with the interior of the conduit when the conduit is rejoined.

A conventional flange cannot be welded directly to pipe which has a plastic liner since the heat generated by the welding process will ordinarily destroy the plastic liner. Furthermore, when pipe repair must be made in the field, particularly in thin-walled pipe or in conduits which have been buried, the open ends cannot be conveniently threaded to attach a flange or nipple.

In accordance with the present invention a coupling joint interconnecting the open ends of two pipe sections comprises a compression collar encircling the open end of each of said pipe sections said compression collar having inwardly projecting means engaging said pipe and a tapered external surface decreasing in diameter from the open end of the pipe; a rigid flange member encircling each of said pipe sections, each flange having a first face lying substantially in the plane of the open end face of said pipe and an opposite face axially removed from said first face, the internal diameter of the flange member tapering to mate with the tapered external surface of said compression collar; and means holding the rigid flange members drawn axially together.

A fully lined end face can be achieved by forming an annular groove in the outer surface of the pipe at a predetermined distance from the open end thereof, and fitting the tapered compression collar to mate with the groove over the end of the pipe, fitting a flange having an inner surface which conforms to and mates with the compression collar and also having a radially extending face which aligns with the open end of the pipe over the compression collar, and inserting a plastic flange member or collar within the open end of the pipe. A plastic flange collar may have a cylindrical body which fits within the plastic liner in the pipe and an outwardly radiating flonge which mates with the exposed end face of the pipe, the end of the compression collar and the face of the connection flange.The cylindrical body extends into the pipe past the groove to insure that any damage to the liner caused by the grooving is covered with plastic. Abutting ends of lined pipe with exposed end faces may thereby be joined to form a fully lined junction between two pipe sections which previously had exposed end faces.

It will thus be observed that when repairs or alterations must be made in string of buried pipe, an entire pipe section need not be removed. Instead, only a small portion of the pipe need be exposed and removed from the conduit and new portion substi tutedforthe portion removed. Using the teachings of this invention, a fully lined conduit is formed which includes the short joint or other conduit means spliced into the conduit. Furthermore, if a T or other apparatus must be installed in the pipe string, only the immediately affected portion of the conduit need be exposed. Therefore, extremely rapid repairs and alterations may be made in a lined conduit and, using the teachings of the invention, a fully lined repair or alteration performed.In an alternative embodiment of the invention, an annular groove is provided in the inner surface of the flange member which carries a sealing gasket, such as an O-ring or the like, to form a seal between the flange and the pipe section, thereby preventing leakage of fluids from the environment surrounding the junction into the junction formed. The alternative embodiment may also be used as the sole sealing means in forming junctions between sections of un-lined pipe.

Other features and advantages of the invention will become more readily understood from the following detailed description taken in connection with the appended claims and attached drawings in which: FIGURE 1 is a sectional view of the open end portions of two lined pipe sections joined in accordance with one embodiment of the invention; FIGURE 2 is a sectional view of the open end portion of a pipe section employing an alternative embodiment of the invention; and FIGURE 3 is a sectional view of the open end of a pipe section employing yet another alternative embodiment of the invention.

As illustrated in the drawings the opposed open ends of two sections of lined metal pipe may be joined in accordance with the invention to form a fully lined junction. Each pipe section 10 may be the open end of any conventional conduit formed from either threaded or non-threaded pipe joints having a liner 11 on the internal surface thereof. Liner 11 may be a conventional tubular liner formed of thermal plastic, such as polyvinyl chloride or other plastic, or may be a protective lining formed in place as by spraying or the like as is well known in the art. Con ventionally, liner 11 is bonded to the internal surface of the pipe 10 to form a plastic lined conduit.

When a section of a conduit formed by joints of pipes such as pipe 10 is removed, the removal is usually accomplished by merely cutting through the pipe. The pipe may be cut for any of various reasons, such as to remove a faulty, leaky or damaged section orto install a T or other apparatus. However, when a portion of the conduit is removed, such as by sawing orthe like, the pipe 10 and the liner 11 are both severed in the same plane leaving an open end. The end face 12 of the pipe 10 isthusexposed and not coated with the liner.

If the pipe sections 10 are to be joined to each other or with a substitute pipe section, T or the like, means must be provided to protect the end faces 12 of the pipe 10.

As illustrated in the drawings an annular groove 13 is formed in the external surface of pipe 10 at a predetermined distance from the end face 12. The groove 13 may be formed by a conventional groov ing tool which cuts a relatively flat-bottomed rectan gular groove 13 as illustrated in Figure 1 or may be a semi-circular groove formed by rolling or the like as illustrated in Figure 2. A plastic end face liner 14 is then positioned within the open end of pipe 10. End face liner 14 comprises an open-ended cylindrical body, the outer dimensions of which substantially conform to the internal dimensions of liner 11 in pipe 10. The end face liner 14 includes a radially extend ing flange 15 which radiates outwardly from one end of the body and mates with the end face 12 of the pipe 10.

The end face liner 14 is preferably of the same material as liner 11. Therefore end face liner may be bonded to liner 11 with a suitable solvent such as methyl ethyl ketone or any other suitable solvent or conventional epoxy cement or the like, depending upon the material of the liner 11 and end face liner 14. A metal compression collar 16 is then fitted over the outer surface of the open end of pipe 10.

Compression collar 16 preferably comprises a pair ofsemi-circularsteel bodies which mate to form an axially elongated ring or band. Alternatively, com pression collar may be a unitary split ring which is expandable to fitoverthe end of the pipe 10. The internal diameterofthe compression collar 16 is pre ferablythe same as the external diameter of the pipe 10 and includes an inwardly projecting means to position the collar 16 and prevent axial movement of the collar 16 with respect to the pipe 10. The inwardly projecting means may be a flange or lip 17 which mates with groove 13 where a groove 13, either rectangular or rounded as shown in Figures 1 and 2, respectively, is formed.The axial length of compression collar 16 is preferably identical with the predetermined distance of the groove 13 from the open end face 12 of the pipe so that the end face of the compression collar opposite the lip 17 lies in the same plane as the end face 12 of the pipe 10. In the embodiment illustrated in Figure 3, all or part of the internal surface of the compression collar 16 is pro vided with gripping ridges or teeth 17a which grippingly engage the outer surface of the pipe. The outer surface 18 of compression collar 16 is tapered, the external diameter increasing in the direction of the end thereof lying in the plane of end face 12 of pipe 10.

A rigid flange 20 having a central opening 21 is positioned overthe end of pipe 10 priorto assembly of the compression collar 16 and insertion of the end face liner 14. The rigid flange 20 has a centrally located opening 21 of non-uniform diameter. The smaller internal diameter of the opening in flange 20 is substantially the same as the external diameter of pipe 10 and is located in the portion thereof at the edge removed from the open end of the pipe 10. The internal diameter of the flange 20 is greatest at the face thereof lying in the plane of the open end face face 12 of the pipe 10.The larger internal diameter is tapered in the same direction as the outer surface 18 of the compression collar 16 so that the tapered internal surface 27 mates with the tapered external surface 18 of the compression collar 16 and further forms a shoulder 19 which mates with the edge of the compression collar 16 adjacent lip 17 as shown in Figures 1 and 2. The axial length of the tapered internal diameter surface 27 of the flange 20 is substantially the same as or slightly less than the axial length of compression collar 16.

Flange 20 includes a plurality of holes 22 parallel with the central opening 21 and disposed around the periphery thereof through which connecter bolts 23 may be passed to accomplish coupling of one pipe joint to another pipe joint or other apparatus.

For connecting two open pipe ends, each having an exposed end face 12 as illustrated in the drawings, the coupling may be formed by abutting the ends of the pipes. The faces of the radially extending flanges on end face liners 14 are drawn together by bolts 23 passing through holes 22. It will be observed that as the flanges 20 are drawn together by connector bolts 23, the tapered internal surfaces 27 mate with the tapered external surfaces 18 on the compression collars 16. Thus the compression collar 16 is radially compressed inwardly by the flange 20 to maintain the lip 17 securely engaged in groove 13.

The lip 17 thus exerts axial force on the pipe 10 through shoulder 19 on the internal surface of the flange 20 engaging the end face of the compression collar 16to draw the end face liners 14 uniformly and snugly into mutual contact. Alternatively, in the embodiment of Figure 3, radial compression of the collar 16 causes teeth 17a to securely engage the pipe 10 and axial force is applied to the collar 16 through shoulder 19 to draw the ends of the pipe sections 10 together.

It will be readily appreciated that the flanges 15 on end face liners 14 mate not only with the end faces 12 of pipes 10, but also with each other and with the end faces of compression collars 16 and the oppos ing faces of flanges 20. Accordingly, a suitable sol vent or cement may be applied to the flanges 15 immediately prior to assembly to form a fully bonded and sealed plastic lined coupling.

In some cases, particularly those involving rela tively thin-walled pipe internally coated with a formed-in-place liner such as a sprayed coating, formation of the groove 13 in the external surface of the pipe may cause damage to the liner 11 on the internal surface of the pipe in the immediate vicinity ofthegroove 13. For exam ple, the liner may crack or become disengaged from the pipe wall, thus exposing the metal pipe wall to fluid passing through the conduit. In order to protect the pipe wall from any such damage which may occur, the tubular body portion of the end face liner 14 should extend into the lined pipe 10 weli past the groove 13 and be securely bonded to the liner 11.In this manner, any cracks or the like formed in liner 11 by formation of the groove 13 will be covered by the end face liner 14, thus ensuring the formation of a fully lined conduit.

As illustrated in Figure 3, an annular groove 30 may be formed in the internal surface ofthe opening 21 in flange 20 which engages the pipe 10 and sealing means, such as an O-ring 31 or the like, fitted therein. The seal formed by the O-ring 31 provides an external seal to prevent fluids from the external environment from entering the joint formed. Thus, when the conduit is used in a corrosive environment or buried, etc., external fluids may not leak into the coupling mechanism to contaminate and corrode the joint-forming mechanism.

It will be apparentthatthe groove and O-ring embodiment may be used in combination with any embodiment of the compression collars 16 shown and described. When used in forming lined junctions in lined pipe, the sealing groove and O-ring serve primarily to prevent leakage of external fluids into thejoint4orming apparatus. However, it should be observed that the elements of the invention shown may be used as shown and described without the plastic end face liner 14 to form junctions between un-lined pipe sections. In this case, a gasket (not shown) may be placed between the abutting faces of flanges 20 to replace flange 15 and the sealing gasket and the O-ring 31 form a fluid-tight seal between the abutting ends of the pipe sections.The interrelationship between the collar 16, the flange 20 and the ends of the pipe 10 are, of course, the same for lined as well as un-lined pipe. Thus the hardware designed in accordance with the invention for forming fully lined joints may also be used for forming un-lined joints.

It will be observed that the method and apparatus described herein may be used on practically any size of metal pipe, either threaded or unthreaded. The coupling may readily be performed in the field on buried pipe with only minimum exposure of buried line. Furthermore, the rigged flanges 20 may be adapted to mate with each other, as shown in Figure 1, or adapted to mate with other apparatus such as a Torthe like which already has an end face liner.

Since the collar 16 extends axially from the shoulder 19 in the flange 20 to the open end face 12 of pipe 10, the collar 16 reinforces the end of the pipe so that the coupling formed by the flange 20 is rigid and stable.

Furthermore, since the outer surface 18 is tapered to mate with the tapered inner surface 27 of the flange, the collar 16 is radially compressed about its full radial periphery to form intimate contact with the pipe yet prevent crushing of the pipe. Thus the collar 16, whether provided with teeth 17a or lip 17, sec urely engages the pipe and stabilizes the junction.

While the invention has been described with particular reference to specific embodiments thereof, it is to be understood that the forms of the invention shown and described in detail are to be taken as preferred embodiments of same, and that various changes and modifications thereof may be resorted to without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A coupling joint interconnecting the open ends of two pipe sections, comprising; a compression collar encircling the open end of each of said pipe sections, said compression collar having inwardly projecting means engaging said pipe and a tapered external surface decreasing in diameter from the open end of the pipe; a rigid flange member encircling each of said pipe sections, each flange having a first face lying substantially in the plane of the open end face of said pipe and an opposite face axially removed from said first face, the internal diameter of the flange member tapering to mate with the tapered external surface of said compression collar; and means holding the rigid flange members drawn axially together.

2. A joint as claimed in Claim 1 in which the larger diameter of the tapered external surface lies in substantially the same plane as the end face of said pipe.

3. A joint as claimed in Claim 1 or Claim 2 in which the internal diameter of the flange member adjacent said opposite face substantially conforms to the external diameter of said pipe section and the internal diameter of said flange member adjacent said first face substantially conforms to the external diameter of said compression collar at the face thereof lying in the plane of said end face of said pipe.

4. A joint as claimed in any preceding claim including an annular groove in the external surface of each of said pipe sections at a predetermined distance from the open end, and in which the inwardly projecting means comprises a lip mating with the groove.

5. A joint as claimed in any preceding claim in which the flange member has a shoulder engaging the end face of the compression collar opposite the open end face of said pipe.

6. A joint as claimed in Claim 4 or Claim 5 wherein said annular groove is rectangular in crosssection.

7. A coupling joint as claimed in Claim 4 or Claim 4 wherein said annular groove is semi-circular in cross-section.

8. A coupling joint as claimed in any one of the preceding claims including an annular groove in an internal surface of said rigid flange member mating with the external surface of said pipe section and further including sealing means carried in said annular groove to provide sealing engagement between said rigid flange member and said pipe section.

9. A coupling joint as defined in Claim 8 wherein said sealing means is an O-ring.

10. A joint as claimed in any preceding claim in which each pipe section has a plastic liner on its internal surface, and comprising a plastic end face liner positioned within the open end of each of said pipe sections, said end face liner comprising an open cylindrical body having outer dimensions substantially conforming to the internal diameter of said plastic liner and having an outwardly radially projecting flange adjacent one end thereof mating with the end face of the open end of said pipe section.

11. A joint as claimed in Claim 10 in which the flanges on the end face liners are held in abutting relationship by the flange members.

12. A coupling joint as claimed in Claim 10 or Claim 11 wherein said cylindrical body of said end face liner extends from the open end of said pipe section past said groove.

13. A coupling joint as defined in any of Claims 10-12 wherein said cylindrical body is bonded to the internal surface of said plastic liner in said pipe section.

14. A coupling joint interconnecting the open ends of two pipe sections constructed and arranged substantially as herein specifically described with reference to any FIGURE of the accompanying drawings.

15. Apparatus for joining the open end of a pipe to other conduit means comprising a collar for encircling the end of said pipe, and having inwardly projecting means for engaging said pipe and a tapered outer surface decreasing in diameter from the open end of said pipe; and a rigid flange having an opening for encircling said pipe and said collar, the internal surface of the opening conforming to the tapered outer surface of said collar.

16. Apparatus as claimed in Claim 15, in which the internal surface of the opening furthest from the open end of the pipe conforms to, and mates with, the external surface of the pipe.

17. Apparatus as claimed in Claim 15 or Claim 16 including an end face liner comprising a cylindrical body, for fitting in the inner diameter of a plastic liner in the pipe and having a radially extending flange for mating with the end face of said pipe.

18. Apparatus as defined in Claim 15 or Claim 16, or Claim 17 wherein said inwardly projecting means comprises a lip for mating with an annular groove formed in said pipe at a predetermined distance from the open end thereof.

19. Apparatus as defined in Claim 17 and Claim 18 wherein the axial length of said cylindrical body exceeds said predetermined distance.

20. Apparatus as claimed in any of Claims 15-19 in which the band is an axially elongate split ring.

21. Apparatus as claimed in Claim 16 including an annular groove in the internal surface of the open ing furthest from the open end of the pipe, and seal ing means carried in said annular groove for forming sealing engagement with the external surface of the pipe.

22. A method of lining the end face of the open end of a pipe having a plastic liner bonded to the internal surface thereof comprising the steps of; forming an annular groove in the outer surface of said pipe at a predetermined distance from the open end of said pipe; encircling the end of said pipe in a collar extending axially from said groove to the end face of the open end of said pipe and having an inwardly projecting lip mating with said groove, said collar having a tapered external surface increasing in diameter in the direction of the open end face of said pipe; placing a rigid flange on the outer surface of said pipe, said flange having an opening substantially conforming to the outer diameter of said pipe and having an internal annularshoulderand an axially tapered internal surface mated with said tapered external surface of said collar; and inserting a plastic end face liner in the open end of said pipe, said end face liner comprising a tubular body having outer dimensions substantially conforming to the inner dimensions of said liner in said pipe and having a flange extending radially from one end of said tubular body, said radially extending flange mating with both the open end face of said pipe and the end face of said collar.

23. The method set forth in Claim 23 including the step of bonding said plastic end face liner to the internal surface of said liner and to the end face of said pipe.

24. The method set forth in Claim 23 or Claim 24, wherein said tubular body is inserted into said open end of said pipe to extend past said annular groove.