Marubeni Tubulars, Inc.

Nkk Corporation

Antares Marketing, S.a.

Oil Technology Services

Erich F Klementich

Edward O Banker

Teruo Suzuki

Jeffrey K Bouche

The tubular connection includes a pin member having external tapered threads extending from a pin nose to a pin base and a box member having internal tapered threads extending from a box base to a box nose. The tapered threads are square or near square threads having stab and load flanks with accommodating grooves. The stab flanks have corner chamfers which engage upon stabbing the pin member into the box member. The comer chamfers increase the clearances between the threads and grooves and guide the crests to the root openings upon relative rotation of the pin and box members. The stab flanks may have an increased thread width at the thread pitch line forming cam flanks which cam the threads into the grooves. The crests and roots of the threads interferingly engage. The pin nose and box base engage to form a metal-to-metal seal and a primary torque shoulder which during power tight make-up causes the load to shift from the stab flanks to the load flanks. The pin nose and box base lock up such that upon the application of further torque, the threads lock up from the pin nose back to the pin base thereby transferring substantially all of the remaining applied torque to the threads whereby the seal becomes insulated from any additional make up torque.

Tubular connection

The metal-to-metal sealing system includes a first seal configuration on one member of the connection and a second seal configuration on the other member. Each seal configuration includes an annular groove and an adjacent annular tooth. The annular groove and annular tooth form three frustoconical surfaces with the groove having an annular undercut surface and the annular tooth having an annular shoulder surface. A seal cylindrical surface and a pre-ramp cylindrical surface extend from the mouth of the groove and a frustoconical ramp forms the transition surface between the seal and pre-ramp cylindrical surfaces. Further, at the base of the outer side of the annular tooth, there extends a cylindrical surface along the main body of the member. Upon makeup of the connection, the ramps and seal cylindrical surfaces guide and align the seal configurations. Initially the center frustoconical surfaces interferingly engage. Upon further tightening of the connection, the teeth are funneled into the grooves with the teeth being wider than the width of the grooves causing the other frustoconical surfaces to interferingly engage. Upon final power tightening of the connection, the annular shoulder surface and undercut surfaces engage whereby upon final makeup, up to seven seals are formed. Six of the sealing surfaces on each seal configuration are cut by a single plunge cut of a carbide tool insert.

Method for producing sealing surfaces on a tubular member

Sealing system

The present invention pertains to a tubular connection having a stabilized center-shoulder seal. The stabilization of the center-shoulder seal is achieved using at least one run-out section of thread adjacent to the center-shoulder seal configuration of each connection member. The run-out section of thread is typically used in combination with a run-in section of thread on the corresponding connection member. Preferably, the center shoulder seal configuration of each connection member is positioned between a run-out thread section and a run-in thread section. (The corresponding connection member will comprise the corresponding sections of run-in and run-out threads, respectively, so there is an interengaging set of run-in and run-out threads). Even more preferably, in addition to the connection having one set of run-out and run-in thread sections adjacent to the center-shoulder seal, the connection has a second set of run-out and run-in threads adjacent to the exterior edges of the connection (A double run-out, run-in stabilization of the center-shoulder seal). The double set of run-out, run-in sections of thread provides the most stable connection. The most preferred center-shoulder seal design is a 'locked double shoulder' design, wherein the cross section of the assembled center-shoulder area exhibits an interlocking double shoulder configuration. The most preferred thread profile is a single hook thread profile wherein the load flank angle is a negative angle and the stab flank angle is about zero degrees. The preferred thread profile comprises chamfered stab flanks at least at locations which will come into contact upon initial telescoping of a connection pin member into a connection box member. The thread is typically a variable width thread having a progressively increasing thread width throughout a continuous section of thread.

Stabilized center-shoulder-sealed tubular connection

The present invention pertains to a tubular connection having a stabilized center-shoulder seal. The stabilization of the center-shoulder seal is achieved using at least one run-out section of thread adjacent to the center-shoulder seal configuration of each connection member. Typically, the at least one run-out section of thread is located adjacent the side of the center-shoulder at which the connection member wall thickness is less. The run-out section of thread is typically used in combination with a run-in section of thread on the corresponding connection member.

Threaded tubular interference fit interconnections and related production techniques are disclosed that are for example useful with large diameter tubular members, including pipe bodies, that can for example function as casing for oil, gas, geothermal, disposal and other wells. In a preferred aspect of the invention there is root-to-crest and/or flank-to-flank interference between nose and inner portions of male and female threads of the disclosed interconnections, such as substantially to seal them against leakage at the maximum internal and/or external pressure rating of the pipe body, and a run-out portion of the male thread and a corresponding portion of the female thread engage one another with interference to retain threaded engagement between said run-out and corresponding portions at the maximum axial force rating of the pipe body and also at the maximum internal and/or external pressure rating of the pipe body. These connections, when applied to API line pipe or other tubular products, can allow them to properly function as large diameter casing exhibiting easy and economical manufacture with existing machinery, easy installation in the field, good balance between geometric and load capacity transparency, and freedom from some undesirable characteristics of prior products.

Threaded tubular connection

The present invention pertains to an improvement in buttress-threaded tubular connections. In particular, the connection is improved by controlling the tubular member thread pitch diameter tolerance to .+-.0.0015 inch, to provide a thread bearing contact pressure which is relatively constant over the entire length of the connection. In addition, the improved connection provides a reduction in hoop stress of about 20% over known buttress-threaded tubing connections. The present invention typically includes the use of variable make-up in combination with the control of the tubular member thread pitch diameter tolerance.

Buttress-threaded tubular connection

A ring gauge is made from the box end of an authenticated precision threaded member and a plug gauge is made from the pin end thereof. The pin end is machined laterally and radially at its nose to ensure complete engagement of the threads. The box end is machined laterally and radially at its internal shoulder for a similar reason. A plunger-activated seal-diameter gauge operates through a radial hole in each of the ring gauge and plug gauge thus made, so that the plungers contact the sealing surface of a measured pin end or box end. Similarly, a plunger-activated standoff gauge operates through a longitudinal opening of the ring gauge and of the plug gauge, the plungers effectively providing a measurement of standoff between the tip of the pin end being measured and the internal surface of the ring gauge shoulder or comparable standoff of the box end. Tabulated measurements of seal diameter and standoff provide data for determining the optimum number of acceptable fits between the pin ends and box ends from a plurality of measured tubular members. Similar gauges, but segmented with a gap, are used to measure taper of the measured threads. The gap size in the gauge determines if the measured taper is slow or fast relative to nominal and, if calibrated, an absolute measurement of taper.

Growing community of inventors

Houston, TX, United States of America

Erich F Klementich