COUPLING ASSEMBLY FOR PREMIUM THREADED PIPE JOINTS

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] This invention relates to premium threaded pipe joints having a glass reinforced epoxy ("GRE") lining system installed. More particularly, the invention relates to a coupling assembly for premium threaded pipe joints that comprises a glass reinforced elastomeric compression ring having a wedge-shaped cross-section with oppositely facing, oppositely inclined side surfaces, each of which contacts and abuts against an oppositely disposed, cooperatively inclined surface of a liner end wedge flange to provide a corrosion-resistant barrier between two adjacent threaded pipe joints.

2. Description of Related Art

[0002] A need exists for an effective and economical corrosion resistant coupling assembly for glass-lined, premium threaded pipe joints.

[0003] Previously known coupling systems are disclosed in the following references: United States Patent Nos. 1,889,868; 3,339,945; 4,706,997; 4,878,285; 5,263,748; 6,042,153; 6,273,474; 7,360,797; and 7,731,246; and in U.S. Pre-patent Publication No. 200902951456.

l SUMMARY OF THE INVENTION

[0004] A corrosion resistant coupling assembly is disclosed for coaxially disposed premium threaded pipe joints having a GRE lining system installed. A preferred embodiment of the subject coupling system comprises two liner end wedge flanges in combination with a reinforced polymeric compression ring. The polymeric compression ring preferably comprises a wedge-shaped cross-section with oppositely facing, oppositely inclined side surfaces, each of which contacts and abuts against an oppositely disposed, cooperatively inclined surface of a liner end wedge flange to provide a corrosion-resistant barrier between two adjacent threaded pipe joints. A preferred material for use as the reinforced polymeric compression ring is glass reinforced polytetrafluoroethylene ("PTFE").

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The apparatus of the invention is further described and explained in relation to the following drawings wherein:

FIG. 1 is a cross-sectional elevation view through one side of a coupling assembly of the invention for two premium threaded pipe joints each having a GRE lining system installed, with the liner end wedge flange of the pin end shown prior to contacting the compressible polymeric ring of the invention;

FIG. 2 is a cross-sectional elevation view through one side of the coupling assembly of FIG. 1, with the liner end wedge flange of the pin end shown upon contacting the compressible polymeric ring of the invention;

FIG. 3 is a cross-sectional elevation view through one side of the coupling assembly of FIGS. 1 and 2, with the liner end wedge flange of the pin end shown fully engaging the compressed polymeric ring of the invention to produce a corrosion resistant barrier between the pin and box ends of the coupled pipe joints;

FIG. 4 is a cross-sectional detail view taken from FIG. 2; and

FIG. 5 is a cross-sectional detail view taken from FIG. 3.

Like reference numerals are used to indicate like parts in all figures of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Referring to FIG. 1, according to one embodiment of the invention, coupling assembly 10 is provided to form a corrosion resistant barrier between two coaxially aligned and threadedly engaged, glass-lined pipe joints having premium threaded pin end 12 and box end 16, respectively. Coupling assembly 10 of the invention is preferable for use as a coupling system for tubing or casing having a GRE lining system installed. Pin end 12 is provided with GRE liner 18 that is held in place by a layer of adhesive or cement 22. Box end 16 is connected to premium threaded pipe joint 14, which is provided with GRE liner 20 that is also held in place by a layer of adhesive or cement 22.

[0007] Coupling assembly 10 preferably comprises a compressible ring 28 that is disposed between two opposed plastic liner end wedge flanges 24, 26, which are located at the ends of GRE liners 18, 20, respectively. As shown in FIG. 1 , inclined side surface 32 of compressible ring 28 is seated against liner end wedge flange 26, which is in turn seated against the end of GRE liner 20. The surface of compressible ring 28 that faces radially outward is slidably engaging the inside surface of box end 16 that is disposed behind premium threads 34. Pin end 12 is partially threaded into box end 16, and the inclined side surface of liner end wedge flange 24 is still spaced apart from the cooperatively aligned, inclined side surface 30 of compressible ring 28. The oppositely disposed side surfaces 30, 32 of compressible ring 28 are also oppositely inclined, with the width of compressible ring 28, when shown in cross-section, is desirably narrower at the surface facing radially inward than at the surface facing radially outward, against the inside surface of box end 16.

[0008] Referring to FIG. 2, the central portion of which is shown in greater detail in FIG. 4, pin end 12 has advanced sufficiently into box end 16 that the leading, inclined surface of liner end wedge flange 24 is contacting, but not yet compressing, compressible ring 28. When liner end wedge flange 24 is disposed in this position relative to compressible ring 28, as seen in FIG. 4, leading edge 33 of pin end 12 is not abutting against cooperatively aligned annular torque shoulder 36 of box end 16. At this point, coupling assembly 10 is fully assembled but has not yet been sufficiently tightened to compress compressible ring 28 and thereby provide a corrosion-resistant barrier in which no metal portions of the two adjacent pipe joints are subjected to direct contact by a fluid that passes through the tubulars during use.

[0009] Referring next to FIG. 3, the central portion of which is shown in greater detail in FIG. 5, pin end 12 has advanced sufficiently into box end 16 that the leading, inclined surface of liner end wedge flange 24 is compressing compressible ring 28, so that coupling assembly 10 thereby produces a corrosion resistant, barrier between pin end 2 and box end 16. When pin end 12 is in this position relative to box end 16, leading edge 33 of pin end 12 will closely approach and abut against cooperating annular torque shoulder 36 of box end 16, as shown in FIG. 5. Coupling assembly 10 of the invention is desirably dimensioned so that as the premium pipe connection is made up to specified torques and torque shoulder interference, there is a forced compression on compressible ring 28. The facing and abutting surfaces of liner end wedge flanges 24, 26 and compressible ring 28 are desirably sized and configured so as to force an interfering wedge between them and thereby trap compressible ring 28 between flanges 24, 26. The narrower width of compressible ring 28 on the side that is radially inward also cooperates with the inclined surfaces of the liner end wedge flanges to reduce the likelihood that a portion of compressible ring 28 will protrude into the inside diameter ("ID") of coupling assembly 10 when compressible ring 28 is under compression.

[0010] According to one embodiment of the invention, liner end wedge flanges 24, 26 are made of a durable, corrosion resistant plastic material and compressible ring 28 is make of a reinforced polymeric material such as 25% glass-filled polytetrafluoroethylene. GRE liner 20 is desirably set back from the top of the weight bore of the coupling ID a distance such that once the end flange 26 is attached to the liner, such as by cementing, the distance from the top of the weight bore to the top of the flange face will be the same as the outside height dimension of compressible ring 28. This is desirably done prior to pumping the mortar backing layer of cement 22 during the lining process. GRE liner 18 at the pin end of the joint of pipe is desirably set back a distance such that when liner end wedge flange 24 is attached to liner 18, the face of flange 24 will extend beyond the end of the pin a specified dimension so as to allow compression on compressible ring 28 when the joint is tightened. The outside diameter ("OD") of compressible ring 28 is preferably selected so that during makeup, the OD of compressible ring 28 is forced against the ID of the connection ID to provide a corrosion barrier.

[0011] Other alterations and modifications of the invention will like wise become apparent to those of ordinary skill in the art upon reading this specification in view of the accompanying drawings, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventors are legally entitled.