A threaded connection for steel pipe that provides high torque performance, high tension performance and high sealability is provided. A threaded connection 1 includes: a tubular pin 10 including a pin shoulder 12, a male thread 11 and a pin seal 13; and a tubular box 20 including a box shoulder 22, a female thread 21 and a box seal 23. The male and female threads 11 and 21 are constituted by wedge threads. The pin seal 13 is provided between the pin shoulder 12 and the male thread 11. The box seal 23 corresponds to the pin seal 13 and is located on the inner peripheral surface of the box 20. When the connection is made up, the pin shoulder 12 is spaced apart from the box shoulder 22. The threaded connection 1 satisfies the following expression, (1):
3%≤(LP−SP)/LP≤7%  (1). In expression (1), LP is the pitch between loading flanks 111 of the male thread 11, and SP is the pitch between stabbing flanks 112 of the male thread 11.

A threaded connection for steel pipe that provides high torque performance, high tension performance and high sealability is provided. A threaded connection 1 includes: a tubular pin 10 including a pin shoulder 12, a male thread 11 and a pin seal 13; and a tubular box 20 including a box shoulder 22, a female thread 21 and a box seal 23. The male and female threads 11 and 21 are constituted by wedge threads. The pin seal 13 is provided between the pin shoulder 12 and the male thread 11. The box seal 23 corresponds to the pin seal 13 and is located on the inner peripheral surface of the box 20. When the connection is made up, the pin shoulder 12 is spaced apart from the box shoulder 22. The threaded connection 1 satisfies the following expression, (1):
3%≤(LP−SP)/LP≤7%  (1). In expression (1), LP is the pitch between loading flanks 111 of the male thread 11, and SP is the pitch between stabbing flanks 112 of the male thread 11.

A flush joint high torque thread that achieves superior tensile efficiency and compression efficiency. In one example, the thread of a pin member and a box member includes a thread a chamfer with angled shoulders on each side of the thread to achieve increased torque. The stab flanks each contain a lead-in chamfer extending no further than a thread pitch line. The load flanks are each tapered. The stab flanks engage each other during assembly, but not upon assembly. The load flanks do not engage each other during assembly, and do engage each other upon assembly. The pipe achieves both a 70% tensile efficiency and a 90% compression efficiency.

A flush joint high torque thread that achieves superior tensile efficiency and compression efficiency. In one example, the thread of a pin member and a box member includes a thread a chamfer with angled shoulders on each side of the thread to achieve increased torque. The stab flanks each contain a lead-in chamfer extending no further than a thread pitch line. The load flanks are each tapered. The stab flanks engage each other during assembly, but not upon assembly. The load flanks do not engage each other during assembly, and do engage each other upon assembly. The pipe achieves both a 70% tensile efficiency and a 90% compression efficiency.

A stainless steel pipe of a predetermined composition is provided that has an axial tensile yield strength of 689 MPa or more, an axial compressive yield strength/axial tensile yield strength ratio of 0.85 to 1.15, and a microstructure that is 20 to 80% ferrite phase by volume with the remainder containing an austenite phase, the stainless steel pipe having pipe end portions at least one of which has a fastening portion for an external thread or an internal thread, and having a curvature radius of 0.2 mm or more for a corner R formed by a bottom surface of a thread root and a pressure-side flank surface of the thread, measured in an axial plane section of the fastening portion.

A stainless steel pipe of a predetermined composition is provided that has an axial tensile yield strength of 689 MPa or more, an axial compressive yield strength/axial tensile yield strength ratio of 0.85 to 1.15, and a microstructure that is 20 to 80% ferrite phase by volume with the remainder containing an austenite phase, the stainless steel pipe having pipe end portions at least one of which has a fastening portion for an external thread or an internal thread, and having a curvature radius of 0.2 mm or more for a corner R formed by a bottom surface of a thread root and a pressure-side flank surface of the thread, measured in an axial plane section of the fastening portion.

A pipe fitting having a first body and a second body that together at least partially define a fluid flow passage. The first body defines a first portion of the fluid flow passage that extends from a first end of the fluid flow passage to a first internal opening. The second body defines a second portion of the fluid flow passage that extends from a second internal opening to a second end of the fluid flow passage. The first body has a first interface surface that surrounds the first internal opening, the first interface surface having a plurality of anti-rotation grooves. The second body has a second interface surface that surrounds the second internal opening and engages with the first interface surface. The first internal opening is in fluid communication with the second internal opening. The second interface surface has a plurality of anti-rotation fingers that are each received by and engage with a corresponding one of the anti-rotation grooves. Rotation of the second body relative to the first body is resisted by the engagement of the anti-rotation fingers with the anti-rotation grooves.

A pipe fitting having a first body and a second body that together at least partially define a fluid flow passage. The first body defines a first portion of the fluid flow passage that extends from a first end of the fluid flow passage to a first internal opening. The second body defines a second portion of the fluid flow passage that extends from a second internal opening to a second end of the fluid flow passage. The first body has a first interface surface that surrounds the first internal opening, the first interface surface having a plurality of anti-rotation grooves. The second body has a second interface surface that surrounds the second internal opening and engages with the first interface surface. The first internal opening is in fluid communication with the second internal opening. The second interface surface has a plurality of anti-rotation fingers that are each received by and engage with a corresponding one of the anti-rotation grooves. Rotation of the second body relative to the first body is resisted by the engagement of the anti-rotation fingers with the anti-rotation grooves.

A threaded joint for casing pipes and production pipes has a threaded portion, and a metal-metal type sealing assembly structure in the form of a combination of sealing elements which provide 100% effective functioning of the joint under compression and tension, inter alia under the effect of internal and external fluid pressure, by observing the size ratio criteria of a ball-and-cone type seal, in which a radial sealing surface has two consecutively arranged toroidal surfaces which, in the event of axial contact between flanges, form, together with a mating sealing surface of a female member, two seals which remain tight under any combination of loads. The technical result of the group of inventions is an increase in the reliability of the threaded joint under the effect of static and variable operating loads, including external pressure, compression, twisting, and combined loads during the bending and turning of a pipe string, wherein the pipes can be used in the construction of wells having a degree of deviation of up to 13°/10 m.

A threaded joint for casing pipes and production pipes has a threaded portion, and a metal-metal type sealing assembly structure in the form of a combination of sealing elements which provide 100% effective functioning of the joint under compression and tension, inter alia under the effect of internal and external fluid pressure, by observing the size ratio criteria of a ball-and-cone type seal, in which a radial sealing surface has two consecutively arranged toroidal surfaces which, in the event of axial contact between flanges, form, together with a mating sealing surface of a female member, two seals which remain tight under any combination of loads. The technical result of the group of inventions is an increase in the reliability of the threaded joint under the effect of static and variable operating loads, including external pressure, compression, twisting, and combined loads during the bending and turning of a pipe string, wherein the pipes can be used in the construction of wells having a degree of deviation of up to 13°/10 m.