A threaded connection for steel pipe with improved sealability against the internal and external pressures is provided. A threaded connection 1 includes a pin 10 and a box 20. The pin 10 includes a male thread 11, a nose 12, a pin shoulder surface 13, and a pin sealing surface 14. The box 20 includes a female thread 21, a box shoulder surface 23, and a box sealing surface 24. The box sealing surface 24 has a seal point SP on the taper surface 242 located at the midpoint thereof as determined along the direction of the pipe axis CL. The distance L.sub.SP between the tip of the nose 12 and the seal point SP as measured in the direction of pipe axis CL is 13 mm or larger. The shoulder angle α between the pin or box shoulder surface 13 or 23 and a plane VP perpendicular to the pipe axis CL is 2 to 13 degrees. The ratio T.sub.B/T.sub.P of the wall thickness T.sub.B of the box to the wall thickness T.sub.P of the pin 10 as measured at the seal point SP is 1.7 or higher.

A connector which relieves a sealing element of torsional strain having a first threaded engagement, optionally, a second threaded engagement, a void therethrough for receiving a tube, and a sleeve positioned between each threaded engagement and the void. The sleeve relieves the tube of torsional strain from rotating the connector.

A threaded connection that provides high sealing performance is provided. A threaded connection (10) includes a pin (1) and a box (2). An inner male thread (13) of the pin (1) includes a parallel portion (131). The parallel portion (131) is located at an end portion of the inner male thread (13) adjacent to the pin inner sealing surface (11), and has thread roots parallel to the pipe axis. An inner female thread (23) of the box (2) includes a tapered portion (231). The thread height in the tapered portion (231) is larger than that in the parallel portion (131). Da<Db is satisfied, where Da is the difference in diameter between adjacent thread crests (231a) in the tapered portion (231) in a longitudinal cross section of the pin (1) and box (2) as found when the connection is not made up, and Db is the difference between the diameter of the thread root (131a) in the parallel portion (13) and the maximum diameter of the pin inner sealing surface (11).

A metal tubular connecting part includes a total axial length, an inner surface, and an outer surface. The inner and outer surfaces delimit a wall, an outer transition surface, and an inner transition surface. The outer transition surface and the inner transition surface delimit a transition thickness of the wall. A first threaded end is defined by a first outer surface portion extending over a first axial length. A second threaded end is defined by a second inner surface portion extending over a second axial length. The sum of the first axial length and the second axial length is less than or equal to the total axial length of the connecting part.

A casing joint includes a tubular including a particular length, a particular diameter, and a first wall thickness; a male connection formed on a first end of the tubular, the male connection including an axial length and a plurality of threads formed on a portion of an external surface of the male connection less than the axial length of the male connection; and a female connection formed on a second end of the tubular opposite the first end, the female connection including an axial length and a plurality of threads formed on a portion of an internal surface of the female connection less than the axial length of the female connection.

A pipe connector for use in high temperature environments, such as those characteristics of molten salt reactors. The pipe connector can be used in any industry that uses pipe connectors, and in particular, can be used in a molten salt system including a reactor requiring a connection rated for greater than 700 C. and up to 15,000 psi. The pipe connector 100 may comprise a pin 110, a seal ring 140, a retainer ring 150, a box 160, a locking nut 180, and a retaining nut 190.

Disclosed is a connecting device for piping for connecting a pipe to another pipe or to another part for piping. The connecting device includes an adapter and a pipe nipple configured to be threadedly engaged with the adapter. The pipe nipple is fixed to an end of a pipe, and an end of another pipe is inserted into the adapter. The adapter includes a hollow adapter body, a cap coupled to the adapter body, a grip ring configured to fix the pipe introduced into the adapter body, a body-sealing member configured to provide a seal between the adapter body and the pipe, a sleeve disposed between the grip ring and the body-sealing member, and a metal sealing member configured to provide a seal between the adapter body and the pipe nipple.

A threaded joint (200) provides for metal-to-metal sealing on the ends of concentrically positioned inner and outer tubes when joining the concentric tubes to a single tube (107). A threaded coupling (105) secures the inner and outer tubes and joins both tubes to a single tube. The threaded connection leverages metal-to-metal sealing on the ends of each tube. The inner tube (102) may differ in length from the outer tube (101) and contains a single thread (211) at its for receiving the threaded coupling. Threading the coupling onto the inner tube establishes four flexing metal-to-metal seals (209A-D) between the threaded joint components. The inner and outer tubes maintain contact at the internal shoulder (104) as a result of preloading. If the tubes are of varying thicknesses, a nut (307) is placed between the internal shoulder and the threaded coupling to preserve contact between the tubes at the internal shoulder.

Disclosed is a connecting device for piping for connecting a pipe to another pipe or to another part for piping. The connecting device includes an adapter and a pipe nipple configured to be threadedly engaged with the adapter. The pipe nipple is fixed to an end of a pipe, and an end of another pipe is inserted into the adapter. The adapter includes a hollow adapter body, a cap coupled to the adapter body, a grip ring configured to fix the pipe introduced into the adapter body, a body-sealing member configured to provide a seal between the adapter body and the pipe, a sleeve disposed between the grip ring and the body-sealing member, and a metal sealing member configured to provide a seal between the adapter body and the pipe nipple.

A threaded joint for oil well steel pipe is provided. The threaded joint includes a pin provided with a male thread, and a box provided with a female thread threadedly engaged with the male thread, and at an outer periphery side sealing portion, a cross-sectional area S1 of the pin at a seal point, and a cross-sectional area S0 of a pipe body portion, which is an unprocessed pin portion, satisfy an expression (S1/S0)10015(%), at an inner periphery side sealing portion, a cross-sectional area S2 of the box at a seal point, and a cross-sectional area S0 of a pipe body portion, which is an unprocessed box portion satisfy an expression (S2/S0)10020(%), and a surface area S3 of a contact portion of an intermediate shoulder between thread rows and the cross-sectional area S0 satisfy the expression (S3/S0)10010(%).