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.

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.

The seamless pipe in which a thin-walled portion in a pipe circumferential direction is formed in a pipe axial direction, in which a line segment formed by connecting one end and the other end of the thin-walled portion along a pipe surface with a shortest distance in a formation direction of the thin-walled portion is inclined at an angle α of 5.0° or more with respect to the pipe axial direction. It is preferable that one end and the other end of the thin-walled portion are set from a region in a pipe selected with a shorter length between a length of 1.0 m in the pipe axial direction and 90% of a length in the pipe axial direction where the thin-walled portion turns once in the pipe circumferential direction.

A threaded connection for steel pipe with improved sealing performance is provided. A threaded connection (1) includes a pin (10) and a box (20). The pin (10) includes a pin shoulder surface (11), a pin sealing surface (12) and a male thread (13). The box (20) includes a box shoulder surface (21), a box sealing surface (22) and a female thread (23). The male thread (13) and female thread (23) are constituted by wedge threads. When the connection has been made up, the pin shoulder surface (11) is in contact with the box shoulder surface (21), the stabbing flank and load flank of the male thread (13) are in contact with the stabbing flank and load flank, respectively, of the female thread (23), and the pin sealing surface (12) is in contact with the box sealing surface (22). The shoulder angle is 4° or larger. The shoulder angle is the angle formed by each of the shoulder surfaces (11, 21) with a plane perpendicular to the pipe axis (CL) when the connection is not made up.

A threaded connection for steel pipe with improved sealing performance is provided. A threaded connection (1) includes a pin (10) and a box (20). The pin (10) includes a pin shoulder surface (11), a pin sealing surface (12) and a male thread (13). The box (20) includes a box shoulder surface (21), a box sealing surface (22) and a female thread (23). The male thread (13) and female thread (23) are constituted by wedge threads. When the connection has been made up, the pin shoulder surface (11) is in contact with the box shoulder surface (21), the stabbing flank and load flank of the male thread (13) are in contact with the stabbing flank and load flank, respectively, of the female thread (23), and the pin sealing surface (12) is in contact with the box sealing surface (22). The shoulder angle is 4° or larger. The shoulder angle is the angle formed by each of the shoulder surfaces (11, 21) with a plane perpendicular to the pipe axis (CL) when the connection is not made up.

Device and methods of protecting a branch connector of a fluid supply pipe header for a fire protection system. A protected branch connector assembly includes a protective device that protects the branch connector fitting from dirt and debris and indicates that an internal seal member is in a desired seated orientation. The protective device includes a plug body inserted within the outlet opening of the branch connector fitting and an indicator in an indicative relationship with the branch connector to indicate that the internal seal member is in the desired seated orientation.

A coupler for lined pipe joints in a lined pipe system. The coupler for a lined pipe system, having lined pipe section ends with an inner diameter. A substantially cylindrical hollow body includes an outer surface, an inner surface, two opposing open ends, and a longitudinal center between the two opposing open ends. A ridge extends radially outwardly from the outer surface at the longitudinal center. A hollow radial barb, with a point having a maximum diameter and a hollow section, is symmetrically disposed on the outer surface between each opposing open end and the ridge wherein the radial barbs extend outwardly from the outer surface and away from the ridge.

A coupler for lined pipe joints in a lined pipe system. The coupler for a lined pipe system, having lined pipe section ends with an inner diameter. A substantially cylindrical hollow body includes an outer surface, an inner surface, two opposing open ends, and a longitudinal center between the two opposing open ends. A ridge extends radially outwardly from the outer surface at the longitudinal center. A hollow radial barb, with a point having a maximum diameter and a hollow section, is symmetrically disposed on the outer surface between each opposing open end and the ridge wherein the radial barbs extend outwardly from the outer surface and away from the ridge.

The invention relates to a scaling device (100) between two pipes (10, 20), each pipe comprising an internal coating (RI10, RI20) which is made from a material resistant to corrosion and/or abrasion, characterised in that the device (100) comprises at least one sealing line (L2, L2′) formed by a circumferential groove (12), which is made in the internal coating (RI10, RI20) of one of the two pipes (10, 20), receiving a circumferential protuberance (22) which is made in the internal coating (RI10, RI20) of the other of the two pipes (10, 20), the protuberance (22) being configured to mechanically interfere radially with the groove (12) over at least one circumferential zone (Z2, Z′2).

The invention relates to a scaling device (100) between two pipes (10, 20), each pipe comprising an internal coating (RI10, RI20) which is made from a material resistant to corrosion and/or abrasion, characterised in that the device (100) comprises at least one sealing line (L2, L2′) formed by a circumferential groove (12), which is made in the internal coating (RI10, RI20) of one of the two pipes (10, 20), receiving a circumferential protuberance (22) which is made in the internal coating (RI10, RI20) of the other of the two pipes (10, 20), the protuberance (22) being configured to mechanically interfere radially with the groove (12) over at least one circumferential zone (Z2, Z′2).