GB2088002A - Pipe connection - Google Patents

Abstract

Pipe joint and method of forming same, wherein the female end 13 is prepared by increasing its internal dimension to slightly less than the external dimension of the male end 11. The male end has a slight bevel or flare and its outside diameter is coated with a combination lubricant sealant. Joining is accomplished by rotating one member of the connection an amount of from a few degrees to several turns while the two members are being forced together. By joining the two members under the above conditions scoring 17, 18 of the two members takes place. The interlocking of the score lines appear similar to shallow screw threads, and cause the members to act as if they are joined by a screw connection. <IMAGE>

Description

SPECIFICATION Pipe connection The present invention relates to a pipe joint and method of forming same for use as a connection means between lengths of pipe and more particuiarly to pipe of the kind used in oil field applications.

Many pipe joining methods are known. Some pipe joints include a bell or female section, a pin or male section and an external clamping ring around the bell. The pin may be sealed with'a suitable adhesive.

One prior art method of forming a pipe joint is disclosed in U.S. Patent No. 4,095,825 issued June 20, 1 978 to Major Gene Butler. The method disclosed in this reference comprises the telescoping of a tapered pin inside a bell having an inner conical tapered section. The taper angle of the pin's conical section is greater than the taper angle of the bell's conical section. An adhesive is disposed in the cavity between the inner conical surface of the bell and the outer conical surface of the pin.

U.S. Patent No. 3,466,738 discloses a method of joining pipe consisting essentially of simply forcing together axially two pipe ends of like diameter, the only preparatory step being the slight flaring of one tip in order to permit the initial entry of the other.

Other prior art patents of interest include: 3,124,874 issued March 17, 1 964 to K.C.

Woolley; 2,874,981 issued February 24, 1959 to Sherwnod Joshua Brady; 4,120,083 issued October 17, 1978 to Marvin C. Echols; 4,064,619 issued December 1977 to Marvin C. Echols et al; 2,498,831 issued February 28, 1950 to F.J.

Veitch; and 3,494,642 issued Febuary 10, 1970 to C.J. Coberly et al.

It is an object of the present invention to provide a pipe joint and method of joining same in which the bell and pin end are interlocked by score lines.

Another object of the invention is to provide a pipe joint and method of forming the pipe joint in which joining is accomplished by rotating one member of the connection an amount of from a few degrees to several turns while the two members are being axially forced together.

Another object of the invention is to provide a relatively low cost and simple method of joining oil field tubular members in which interlocking is, at least in part, effected by means of score lines causing the members to act as if they are joined by a screw connection.

Other objects, features and advantages of the invention will be apparent from the drawings, the specification and the claims.

A pipe joint between male and female oil field tubular members wherein the improvement comprises: a metal-to-metal interference fit having an interlocking spiral score thread therebetween.

The method of forming joints between tubular members having a male end and a female end, the improvement comprising: forming a female end on a first tubular member to have an inner diameter slightly smaller than the outer diameter of the male end of a second tubular member; inserting the male end of said second member into the female end of said first tubular member while establishing relative rotation therebetween about a substantially common longitudinal axis to form a metal-to-metal interference fit causing interlocking spiral scoring therebetween.

Figure 1 is a longitudinal sectional view of the male or pin end of a pipe; Figure 2 is a longitudinal sectional view of the female or bell end of a pipe; Figure 3 is a longitudinal sectional view of a completed joint with the resultant deposits of sealant; Figure 4 is a partly sectional plan view of a separated pipe joint, illustrating the score lines or screw thread like marks formed in accordance with the present invention; and Figure 5 is a sectional view showing a device for both telescoping and rotating the pin inside the bell.

Figure 6A is a sectional view of a second embodiment of the device for both telescoping and rotating the pin inside the bell.

Figure 6B is a top view of the cam guide walls of the device shown in Figure 6A.

With reference to Figs. 1-5 the present invention, in basic terms, encompasses a pipe joint and method for joining tubular members.

The pipes to be joined together may be of the type provided with pin and bell ends. For example, pipe 10 has a pin end 11 and pipe 12 has a bell end 13. The bell end may be formed in any conventional manner.

The bell or female end 11 is prepared by increasing its inner diameter to slightly less than the external dimension of the pin or male end 11.

The length of this expanded end area may vary to accommodate specific requirements.

The pipe 12 including portions of the bell section may contain an internal or external coating or plating 14.

The external surface of the pen end 11 and/or the internal surface of the bell section are preferably coated with a combination lubricantsealant such as an epoxy resin.

The pin end 11 is slightly beveled or flared around its outside diameter 15 to facilitate entry into the bell 13. The pipe 10 may contain an internal coating or plating 16. Thus the method of joining pipe in accordance with the invention may be practiced with either coated or uncoated pipe.

As noted above, the bore formed by the cylindrical inner wall of the bell 13 has a diameter slightly smaller than the diameter of the outer cylindrical wall of the pin 11 , so as to form a tight, metal-to-metal, mechanical interference fit between said wall sections.

In accordance with the invention, joining is accomplished by rotating one member of the connection such as pipe 12 relative to the other pipe 10 an amount of from a few degrees to several turns while the two members are also being forced together. The insertion of the male member 11 into the undersized female member 13 while rotating one such member relative to the other accomplishes the linkage mechanism in accordance with an important aspect of this invention.

As a result of the twist-interference fit joining of the two members scoring of the outside surface of the male member and inside surface of the female member is effected.

The interlocking of these score lines 1 7 and 1 8 function substantially as or similar to shallow screw threads, and substantially cause the members to act as if they are joined by a screw connection.

Separation of the connection under tension causes either expansion of the outer member or crushing of the inner member, or a combination of these two modes, of an amount equal to the depth of the score lines. If forced to rotate while being separated the joints will unscrew under great resistance due to the increased length of the score lines.

As apparatus for making the joint of the present invention is schematically illustrated in Fig 5. The arrangement shown in Fig. 5 is illustrated in connection with the forming of a pipe joint with pipe 10 and 12 which already have a pin 11 and a bell 13 section, respectively. The apparatus comprises two opposing block members 1 9 and 20. Each block member has a central bore therethrough which is coaxial with the longitudinal axis of the piles 1 0 and 12, and teeth constructed to grip the pipe. The block member 19 and 20, may have tapered tool bore openings (not shown) or clamping means (not shown) for urging the teeth against the pipe sections 12 and 10, respectively.

Block member 19 may contain an integral gear wheel 21 having a central bore therethrough which is coaxial with the longitudinal axis of the pipes 10 and 12. Gear wheel and block member 19 are rotatably clamped around pipe section 12 and axially fixed in position by use of suitable conventional mounting means.

The block member 19 and gear wheel 21 are rotated at a selected speed by means of a motor 22 driven gear 23 which meshes with the teeth of gearwheel 21.

Block member 20 is axially movable toward or away from block member 19, for example, by means of a pair of hydraul:'cally-opernted cylinders 24 and 25.

Thus Fig. 5 diagrammatically illustrates how pin 11 is forcible inserted into the bell's cylindrical section 26 with the hydraulically-operated cylinders 24 and 25 actuated to move the pipe 10 in the direction of arrows 27. During the axial translation of pipe 10 the block member 19 and.

therefore, pipe 12 are rotated relative to pipe 10, for example, as indicated by arrow 28. In this manner, a spiral interference fit is effected resulting in the score lines 17 and 18 on the respective engaging (scraping) metal-to-metal surfaces.

The yielding of the bell and pin walls do not exceed the elastic limit of the pipe's material to maintain proper restraining force coupled with the linkage mechanism of the present invention, i.e., interlocking score lines functioning somewhat as shallow screw threads.

Referring now to Figs. 6A and 6B, an alternative embodiment of the device in Fig. 5 is shown. The pipe connecting apparatus is similar to that shown in Fig. 5 with the exception that the motor 22, gear wheels 21 and 23 and block member 19 are replaced by a stationary, i.e., non-rotating, block or clamping member 30 and a cammed block member 31. Block member 31 has diametrically opposed cam follower arms 32 and 33 (shown in phantom outline) which extend into a cam or channel cutout in guide mounting plates 34 and 35, respectively. When actuated, the hydraulically-operated cylinders 24 and 25 urge the block member 31 toward block member 30 to force pipe 10 into the bell section 26 of pipe 12.

The cam follower arms 32 and 33 are guided by the channel cutouts in the guide walls 34 and 35 to cause rotation of pipe 10 during the inward motion of block member 31. Fig. 6B illustrates, e.g., guide plate 34 having a diagonal channel cutout 36. In this manner, pipe 10 is caused to be inserted into the bell end 26 of pipe 12 with a rotating or twisting motion.

Although specific embodiments of the invention has been decribed, it is to be understood that the invention comprises all modifications and equivalents within the scope of the appended

Claims (9)

claims. CLAIMS

1. A pipe joint between male and female oil field tubular members wherein the improvement comprises: a metal-to-metal interference fit comprising interlocking spiral score surfaces.

2. A pipe joint between a pin end and a ball end of oil field tubular members wherein the improvement comprises: a metal-to-metal interference fit having interlocking circumferential score threads therebetween.

3. A pipe joint as in claim 1, wherein: the tubular members are steel and the inner diameter of said female member is approximately 0.5 inch less than the outer diameter of the male member prior to joining said members,.said female member has a modulus of elasticity of between 28.5 x 106 pounds per square inch and 30 x 106 pounds per square inch, said male member has a modulus of elasticity of between 28.5 x 106 pounds per square inch and 30 x 106 pounds per square inch.

4. A pipe joint as in claim 3, wherein: the female member has in inner surface hardness of between 68 and 100 on the Rockwell B hardness scale; and the male member has an outer surface hardness of between 68 and 100 on the Rockwell B hardness scale; wherein the metal-to-metal interference fit causes scoring of the inner surface of the female member and scoring of the outer surface of the male member so as to function substantially as an interlocking screw thread therebetween.

5. The method of forming joints between tubular members having a male end and a female end, the improvement comprising: forming a female end of a first tubular member to have an inner diameter slightly smaller than the outer diameter of the male end of a second tubular member; inserting the male end of said second member into the female end of said first tubular member while establishing relative rotation therebetween about a substantially common longitudinal axis to form a metal-to-metal interference fit causing interlocking spiral scoring therebetween

6. The method of claim 4 comprising the further step of: applying a lubricant-sealant to a portion of at least one of the metal-to-metal contacting surfaces between the female end and the male end.

7. The method of fastening together metal pipe having a bell end and a pin end comprising: selecting a first pipe having a bell end with an inter bore diameter: selecting a second pipe having a pin end with an outer diameter relative to the inner bore diameter of the first pipe to define a metal-tometal interference fit therewith, said pin end being flared to facilitate joining of said pin end and bell end; coating said pin end and/or said bell end with a lubricant-sealant; and inserting the pin end of the second pipe into the bell end of the first pipe with relative rotational motion between the first and second pipes to define an interlocking score and ridge between the inner surface of the bell end of the first pipe and the outer surface of the pin end of the second pipe.

8. A pipe joint between male and female oil field tubular members substantially as described herein with reference to the accompanying drawings.

9. A method of forming joints between tubular members having a male end and a female end, substantially as described herein.