A non-frustoconical coupling provides a mechanical connection used in fluid transport for hydrocarbon recovery operations.

A sealing system connecting first and second tubular members includes a first curvilinear sealing surface on the first tubular member and a second curvilinear sealing surface on the second tubular member. Both the first and second curvilinear sealing surfaces are disposed between two sets of threading on the respective first and second tubular members. When the first and second tubular members are in a connected configuration, the first and second curvilinear sealing surfaces contact and interfere to form an annular curvilinear center seal. A relief pocket may be disposed adjacent to the first and/or second curvilinear sealing surfaces to contain excess lubricant between the first and second tubular members.

A threaded connection for steel pipe is provided that can be made up quickly and appropriately. The threaded connection includes a steel pipe 20m, a steel pipe 20f, and a coupling 50 for connecting the steel pipes 20m and 20f. The pipe bodies 21m and 21f of the steel pipes 20m and 20f include annular marking grooves 23m and 23f, respectively, formed on the outer peripheries of the pipe bodies 21m and 21f.

A threaded connection with good internal-pressure and external-pressure sealability while preventing galling is provided. A threaded connection 1 includes a pin 10 and a box 20. The pin 10 includes a pin lip 11, a pin metal seal 13, and a cylindrical inner machined surface 14. The pin metal seal 13 includes a pin seal taper surface 16 and a pin seal curvature surface 17. The box 20 includes a box metal seal 22 parallel to the pin seal taper surface 16. The pin metal seal 13 sealingly contacts the box metal seal 22 at a seal point SP. The threaded connection satisfies the following expressions, (1) and (2),

L>Lm>Ls  (1), and

tb/tp>1.6  (2).

L is the length of the pin lip 11; Lm is the distance between the tip AP of the pin and the end point of the cylindrical inner machined surface 14; Ls is the distance between the tip AP of the pin 10 and the seal point SP; tb is the wall thickness of the box 20 as measured at the seal point SP when the connection is made up; and tp is the wall thickness of the pin 10 as measured at the seal point SP.

A mechanical connector, including a telescopically assembled mechanical connector, is provided with one or more sets of threads on substantially matching frustoconical surfaces of a pin and a box of the connector. Thread generatrix angles on the loaded and unloaded sides of the threads are measured to normals to the shared axes of the box and of the pin. This invention introduces mismatching of the generatrix angles along the interacting surfaces on the loaded and/or unloaded sides of the threads, which result in slight interference fit(s) along the thread surfaces. The effect is more even distribution of the bearing loads on the threads, reductions in the maximum shear loading and more uniform bending of the threads. Already good leak resistance of the connector can be additionally improved. The above modifications can be introduced to traditional connectors and to connectors designed to transfer high torsional loads.

A threaded connection includes a pin including a wedge male thread having a varying-thread-width portion and a box including a wedge female thread having a varying-thread-width portion. The threaded connection is constructed such that, when both stab flanks and load flanks of the male thread of the pin contact the box, the shoulder on the pin is not in contact with the shoulder on the pin, and, with a further rotation in the make-up direction, the shoulder on the pin is capable of contacting the shoulder on the pin before the threads (i.e. male and female threads) yield.

A threaded connection for steel pipe is provided that prevents galling on the sealing surfaces during make-up while providing high sealing performance after completion of make-up. The pin (10) includes a nose (112) including a pin taper guide surface (112a) and a pin sealing surface (113) including a taper surface (113a). The box (20) includes a nose-receiving portion (22) including a box taper guide surface (22a), a box sealing surface (23) including a taper surface (23a), and a buffer surface (24). The taper angle of the taper surfaces (113a, 23a) includes a second taper angle larger than the taper angle of the taper guide surfaces (112a, 22a). The threaded connection (1) is constructed so as to satisfy Dp2>Db2>Dp1 and Lb2>Lp2. The buffer surface (24), located between the box taper guide surface (22a) and taper surface (23a), has a length of 0.75 mm or larger, and is located outward of an imaginary plane (V) determined along radial directions.

Threaded tubular connection comprising a tubular female end extending from a main body of a first tubular member, and a tubular male end extending from a main body of a second tubular member, such that the tubular female end comprises a machined outer cylindrical surface close to the female free end having a first outer diameter and a second machined outer cylindrical surface above a threaded portion of the female end, a second outer diameter of the second outer cylindrical surface being bigger than the first outer diameter.

A connector for connecting pipes and for use with power tongs have a die length. The connector includes a body with threaded connection portions at each end of the body on an inside surface of the body. The connector includes a gripping surface defined on an outside surface of the body between the threaded connection portions. The gripping surface is at least as long as the die length. The connector includes a reinforced portion of the body proximate each of the threaded connection portions for increasing resistance to deformation of the body upon being connected with a pipe. The gripping surface and the reinforced portion together facilitate an increase in connection torque of pipes connected with the connector.

A threaded connection between adjacent drill string components comprises a threaded female connection end adapted to receive a correspondingly threaded male connection end, the two ends each having first and second portions of different tapers. Tubular members, drill string tools and other drill string components comprising the female or male ends described herein are also provided.