Background of the Invention

This invention relates to connecting threaded tubular pipes together through the use of a novel thread design for greatly improving the torsional,strength of the connection. The invention is particularly useful for connecting pipes used in the gas and oil well industries but is not limited thereto and may also be used in drilling wells for accessing water. More particularly, the invention is useful with what is generally referred to as a wash pipe which is used as part of a fishing operation for retrieving broken or stuck parts in an oil well. Present day wash pipes,can range from 2-1/4 inches to 16,inches in diameter.

Currently, gas and oil wells are drilled vertically for many thousands of feet and are then turned to continue drilling horizontally. The threaded connection used with conventional, standard, wash pipes have an unacceptable failure rate caused by a combination of the box, or cup, i.e., the female component swelling and/or the pin or male component collapsing such that the box "swallows" the pin, thereby rendering the connection impossible to unscrew resulting in downhole failure of one or more components.

Summary of the Invention

The present invention provides a unique threaded connection which results in a roughly 50% increase in torsional capacity over the heretofore conventional or standard connection. The novel threading provides an acute angle, typically on the order of 15 degrees, where the threads on one pipe meet with the threads of an adjacent pipe. Likewise, a similar angle, on the order of 15 degrees, is provided at the shoulders or ends of the box and pin. The combination of these angles results in interlocking the box and pin to withstand high torsional loads. The radial component of force generated under torsional loads forces the box onto the pin and the pin into the box. This connection allows the box to resist swelling and the pin to resist collapsing thereby resulting in a vastly improved connection that is less likely to fail under increased torsional loads.

The invention is useful any place that pipes are joined together whether they be water pipes, oil pipes, gas pipes, or wash pipes, including,plastic pipes or metal pipes.

Brief Description of the Drawings

FIG. 1 is a fragmentary, longitudinal, sectional view of a prior art threaded connection for a 5-3/4 inch standard tubular wash pipe. Details A, B, and E illustrate enlarged views of features of the connection.

FIG. 2 illustrates the failure mode of the prior art connection of FIG. 1.

FIG. 3 is a fragmentary, longitudinal, sectional view of the threaded connection for a 5-3/4 inch tubular wash pipe showing the present invention. Details C, D, and F illustrate enlarged views of key features of the invention.

FIG. 4 illustrates.the secure connection of the box and pin provided by the present invention.

Detail Description of Prior Art and the Invention FIG. 1 shows a prior art, threaded connection of a flush joint wash pipe (FJWP), generally indicated by the numeral 10, having an internal, helically, threaded box 12 and an external, helically, threaded pin 14.

As is best illustrated in Detail A, the thread 16 of the box 12 has a vertical face 18 in engagement with a face 29 on thread 22 on the pin 14. Face 29 is canted forward at an angle of 5 degrees from the vertical face 18. This angle is such that the forces generated by screwing the connection together creates a radial component that tends to cause the box 12 to swell or expand, and also tends to cause the pin 14 to collapse.

As is best illustrated in Detail B, the terminal end 24 of the box 12 and the shoulder 26 of the pin 14 are each provided with vertical, or flat, engaging faces which offer no resistance to box 12 swelling, or pin 14 collapsing.

As is best illustrated in Detail E, the shoulder 28 of box 12 and the terminal end 30 of pin 14 have vertical faces in engagement with each other. These faces offer little or no resistance to the box 12 swelling or the pin 14 collapsing.

FIG. 2 illustrates .failure of the threaded connection of FIG. 1 when the connection is subjected to excessive torsional load. The terminal end 24 of the box 12 and the terminal end 30 of.pin 14 get displaced as the box 12 swells or expands while the pin 14 collapses and is "swallowed" by the box 12.

FIGS. 3 and 4 illustrate the threaded connection, generally indicated by the numeral 40, of the present invention, having an internal, helically, threaded box 42 and an external, helically, threaded pin 44.

As is best illustrated in Detail C, the.thread 46 of box 42 has a face 48 in engagement with a face 50 on thread 52 on the pin 44. Face 48 and face 50 are canted at an angle of about 15 degrees from the vertical in the direction away from the adjacent open terminal end 60 of the pin 44 and in the direction of the adjacent open terminal end 54 of the box 42. It is to be noted that this angle is canted in the opposite direction than the 5 degree angle shown in the prior art in FIGS. 1 and 2.

As is best illustrated in Detail F, the terminal end 58 of box 42 and the end 60 of pin 44 are each provided with adjoining faces that are canted on the order of 15 degrees from the vertical in a direction towards the threaded portions of the box 42 and pin 44.

As is best illustrated in Detail D, the box 42, at its open terminal end 54, and the shoulder 56 of the pin 44 have faces that are canted at an angle of about 15 degrees in the direction toward the threaded portions of the box 42 and the pin 44.

The combination of these three angles, shown in Details C, D, and F, results in interlocking the box 42 and pin 44 under high torsional loads. As is clear from Detail D and FIG. 4, the terminal end 54 of box 42 cannot slip past the shoulder 56 of pin 44, while the terminal end 60 of pin 44 can not slip past the shoulder 58 of box 42, as shown in Detail F.

It is clear from the foregoing that the present invention, as shown in FIGS. 3 and 4, provides a threaded connection that is clearly superior to the prior art shown in FIGS. 1 and 2 and allows for substantially increased torsional loading without failure of the threaded connection. Test data provides evidence that the threaded connection of the present invention provides for an improvement over the threaded connection of prior art on the order of fifty percent.