Vallourec Oil and Gas France

Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Yousuke Oku

Masaaki Sugino

Satoshi Maruta

Sadao Douchi

Tatsuya Yamamoto

Keita Inose

Russell Elder

Yoshinori Ando

Tadashi Nakamura

Kunio Goto

Pierre Bernard Martin

Kazuya Ishii

Bertrand Maillon

Shin Ugai

Akira Wada

Daly Daly

Alan Fothergill

Fumio Ota

Yohinori Ando

Elder Russell

Pierre Martin

In a threaded connection for pipe having a two-step thread construction with intermediate shoulder surfaces, compression resistance is further improved. Upon completion of make-up of the pinand box, the diameter of a stabbing clearance is 0.15 mm or smaller, where the stabbing clearance is defined between the stab flank of a male thread including an inner thread portionand an outer thread portionand the stab flank of a female thread including an inner thread portionand an outer thread portion, thereby causing the stab flanks of the male and female threads to start to be in contact before the angle of rotation θ of the intermediate shoulder surfacesandas appearing in a longitudinal cross section starts to rapidly increase, thus preventing accumulation of damage in the intermediate shoulder surfacesand

Threaded connection for pipe

A threaded connection for pipe in which the axial distance between the box intermediate shoulder surface and the box end shoulder surface of the box before make-up, L, is larger than the axial distance between the pin intermediate shoulder surface and the pin end shoulder surface of the pin before make-up, L, such that, upon completion of make-up, the pin and box intermediate shoulder surfaces and are in contact and function as torque shoulders, while the pin and box end shoulder surfaces are in light (or no) contact. The difference between the axial distances, (L−L), is such that, when the pin and box are made up and upon application of an axial compressive load, the pin and box are slightly axially compressed by the compressive load and the pin end shoulder surface comes into pressure contact with the box end shoulder surface to bear part of the compressive load.

A high-torque threaded connection with male and female threadforms constituted by wedge threads is provided with high shear resistance and high torque resistance. The radius of curvature rof the base of the load flank of the first thread, located at the end of the male threadformassociated with the tip, is not lower than the thread height Th×0.14, and more preferably not lower than Th×0.16, to improve the shear resistance of the first thread. Further, the thread pitch may be reduced to increase the number of threads to increase the area of contact for load flanks, or only the radius of curvature of the base of the load flank of the first thread located at the end of the male threadform associated with the tip may be increased and smaller radii of curvature may be provided for the other portions to increase the area of contact for load flanks, thereby maintaining high torque resistance.

Threaded connection for steel pipe

In a threaded connection for pipe with a two-step thread construction, including intermediate shoulders, during stabbing, the internal-pressure sealing surface of the pin near its tip is prevented from contacting the intermediate shoulder of the box and thus receiving damage. L, L, hand hshown in FIG.satisfy Expressions (1) and (2), provided below. θis the angle of slope of the straight line connecting the two ends, as determined along the axial direction, of the internal-pressure sealing surface of the pin. Expression (3), provided below, is also satisfied.  (1)()×tan θ  (2)  (3)

A threaded connection for pipes includes a pin, a box, a shoulder part plating layer, and a non-shoulder part plating layer. The shoulder part plating layer has an outermost layer formed of a high friction coefficient plating layer, and is arranged on a pin side shoulder part and/or a box side shoulder part. The non-shoulder part plating layer has an outermost layer formed of a low friction coefficient plating layer having a coefficient of friction lower than a coefficient of friction of the high friction coefficient plating layer, and the non-shoulder part plating layer is arranged on at least one of a pin side thread part, a pin side metal seal part, a box side thread part, and a box side metal seal part.

Threaded connection for pipes

In a threaded connection of a two-step thread construction including intermediate shoulder surfaces, a break is prevented near the intermediate critical cross sections upon application of a tensile load, and the intermediate shoulder surfaces are easier to create, thus improving productivity. The outer periphery portion of a pin located between an intermediate shoulder surface of the pin and a second male thread is provided with a circumferential groove including a curved surface smoothly contiguous to the intermediate shoulder surface, thereby mitigating plastic strains generated near the pin intermediate critical cross section PICCS. The inner periphery portion of a box located between an intermediate shoulder surface of the box and a first female thread is provided with a circumferential groove including a curved surface smoothly contiguous to the intermediate shoulder surface, thereby mitigating plastic strains generated near a box intermediate critical cross section BICCS.

Threaded connection

A threaded connection for large diameter steel pipe exhibits high torque resistance and high sealability and, at the same time, provides a shear resistance that suits the size of the steel pipe to be connected. The threaded connection includes a tubular pin provided on a tip of a steel pipe with large diameter, and a tubular boxadapted to be drawn up on the pin as the pin is screwed in. The pin includes a male threadform made with a taper thread. The box includes a female threadform made with a taper thread. Each of the threadforms are wedge threads and have a dovetail-shaped cross section. The male threadform is designed such that the width of the thread in an end region of the male threadform closer to the tip is set to a size corresponding to the size of the pipe body of the steel pipe.

A threaded connection for steel pipe with improved sealing performance is provided. A threaded connection () includes a pin () and a box (). The pin () includes a pin shoulder surface (), a pin sealing surface () and a male thread (). The box () includes a box shoulder surface (), a box sealing surface () and a female thread (). The male thread () and female thread () are constituted by wedge threads. When the connection has been made up, the pin shoulder surface () is in contact with the box shoulder surface (), the stabbing flank and load flank of the male thread () are in contact with the stabbing flank and load flank, respectively, of the female thread (), and the pin sealing surface () is in contact with the box sealing surface (). The shoulder angle is 4&#xb0; or larger. The shoulder angle is the angle formed by each of the shoulder surfaces () with a plane perpendicular to the pipe axis (CL) when the connection is not made up.

A threaded connection with good internal-pressure and external-pressure sealability while preventing galling is provided. A threaded connectionincludes a pinand a box. The pinincludes a pin lip, a pin metal seal, and a cylindrical inner machined surface. The pin metal sealincludes a pin seal taper surfaceand a pin seal curvature surface. The boxincludes a box metal sealparallel to the pin seal taper surface. The pin metal sealsealingly contacts the box metal sealat a seal point SP. The threaded connection satisfies the following expressions, (1) and (2),&#x2003;&#x2003;(1), and&#x3e;1.6&#x2003;&#x2003;(2).L is the length of the pin lip; Lm is the distance between the tip AP of the pin and the end point of the cylindrical inner machined surface; Ls is the distance between the tip AP of the pinand the seal point SP; tb is the wall thickness of the boxas measured at the seal point SP when the connection is made up; and tp is the wall thickness of the pinas measured at the seal point SP.

A threaded connection includes a pin and a box. The pin includes, in the order from a free end side of the pin toward a tubular body side thereof, an inner sealing surface, an inner male threaded portion, a shoulder portion, an outer male threaded portion, and an outer sealing surface. The box includes, in the order from a tubular body side of the box toward a free end side thereof, an inner sealing surface, an inner female threaded portion, a shoulder portion, an outer female threaded portion, and an outer sealing surface. Between the inner sealing surface and the inner female threaded portion of the box, an inner groove along a circumferential direction is provided, and some threads of the inner male threaded portion of the pin are contained in the inner groove.

Threaded connection for steel pipes

A threaded connection for steel pipe that provides high torque performance, high tension performance and high sealability is provided. A threaded connectionincludes: a tubular pinincluding a pin shoulder, a male threadand a pin seal; and a tubular boxincluding a box shoulder, a female threadand a box seal. The male and female threadsandare constituted by wedge threads. The pin sealis provided between the pin shoulderand the male thread. The box sealcorresponds to the pin sealand is located on the inner peripheral surface of the box. When the connection is made up, the pin shoulderis spaced apart from the box shoulder. The threaded connectionsatisfies the following expression, (1):3%&#x2264;()/&#x2264;7%&#x2003;&#x2003;(1). In expression (1), LP is the pitch between loading flanksof the male thread, and SP is the pitch between stabbing flanksof the male thread

The threaded joint includes a pin and a box. The pin includes a taper male thread part, and the box includes a taper female thread part to be engaged with the taper male thread part. The male thread part is divided into a first region on the free end side of the pin, and a second region on the tubular side of the pin along a tube axis direction. The taper ratio of the first region is greater than the taper ratio of the second region. The taper ratio of the first region is greater than the taper ratio of the female thread part. The taper ratio of the second region is equal to or greater than the taper ratio of the female thread part.

Threaded joint for steel pipes

A threaded connection for steel pipe that provides both high torque performance and high tension performance is provided. A threaded connectionincludes a tubular pinformed by one tip portion of a steel pipe and a tubular boxadapted to be made up on the pinas the pinis inserted into the box. The pinincludes a male threadprovided on an outer periphery of the pin, the male thread being a wedge thread. The boxincludes a female threadcorresponding to the male threadand provided on the inner periphery of the box, the female thread being a wedge thread. The threaded connectionsatisfies the following expression, (1):3%&#x2264;()/&#x2264;8%&#x2003;&#x2003;(1). In expression (1), LP is the pitch between loading flanksof the male thread, and SP is the pitch between stabbing flanksof the male thread

A threaded connection for steel pipe is provided that improves its internal-pressure sealability while maintaining the high external-pressure sealability of a threaded connection having a nose used in a steel pipe with large diameter and large wall thickness. In a threaded connection for connecting steel pipe bodies each having an outer diameter equal to or larger than 7 inches and a wall thickness equal to or larger than 0.7 inches, Expression (1) in the description is satisfied and t/t&#x3e;1.4, where &#x3b4; [mm] is the clearance between the outer surface of the pin and the inner surface of the box upon make-up as measured at the borderline between the pin taper surface and the pin round surface, D [inch] is the outer diameter of the steel pipe body, t [inch] is the wall thickness of the steel pipe body, L [mm] is the distance between a pivot point, which is a position, in the region of contact between the pin sealing surface and the box sealing surface, which is closest to the tip of the pin, and the tip of the pin upon make-up as measured along the pipe-axis direction, t[mm] is the wall thickness of the pin as measured at the pivot point, and t[mm] is the wall thickness of the box as measured at the pivot point.

A threaded connection for steel pipe with improved sealability against the internal and external pressures is provided. A threaded connectionincludes a pinand a box. The pinincludes a male thread, a nose, a pin shoulder surface, and a pin sealing surface. The boxincludes a female thread, a box shoulder surface, and a box sealing surface. The box sealing surfacehas a seal point SP on the taper surfacelocated at the midpoint thereof as determined along the direction of the pipe axis CL. The distance Lbetween the tip of the noseand the seal point SP as measured in the direction of pipe axis CL is 13 mm or larger. The shoulder angle &#x3b1; between the pin or box shoulder surfaceorand a plane VP perpendicular to the pipe axis CL is 2 to 13 degrees. The ratio T/Tof the wall thickness Tof the box to the wall thickness Tof the pinas measured at the seal point SP is 1.7 or higher.

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Tokyo, Japan

Yousuke Oku