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.

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 pin 2 and box 3, 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 portion 27 and an outer thread portion 23 and the stab flank of a female thread including an inner thread portion 36 and an outer thread portion 32, 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 surfaces 25 and 34 as appearing in a longitudinal cross section starts to rapidly increase, thus preventing accumulation of damage in the intermediate shoulder surfaces 25 and 34.

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 pin 2 and box 3, 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 portion 27 and an outer thread portion 23 and the stab flank of a female thread including an inner thread portion 36 and an outer thread portion 32, 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 surfaces 25 and 34 as appearing in a longitudinal cross section starts to rapidly increase, thus preventing accumulation of damage in the intermediate shoulder surfaces 25 and 34.

An oil-well metal pipe according to the present disclosure has a pipe main body including a first end portion and a second end portion. The pipe main body includes a pin formed at the first end portion, and a box formed at the second end portion. The pin includes a pin contact surface including an external thread part, and the box includes a box contact surface including an internal thread part. The oil-well metal pipe according to the present disclosure also includes a resin coating containing a resin, a solid lubricant powder, and copper phthalocyanine on or above at least one of the pin contact surface and the box contact surface.

An oil-well metal pipe according to the present disclosure has a pipe main body including a first end portion and a second end portion. The pipe main body includes a pin formed at the first end portion, and a box formed at the second end portion. The pin includes a pin contact surface including an external thread part, and the box includes a box contact surface including an internal thread part. The oil-well metal pipe according to the present disclosure also includes a resin coating containing a resin, a solid lubricant powder, and copper phthalocyanine on or above at least one of the pin contact surface and the box contact surface.

A fitting for connecting a branch conduit to a liner installed in a main pipe is configured to mechanically connect to the branch conduit as it is inserted into the branch conduit from inside the main pipe. The mechanical connection is established without rotating the fitting. The fitting can include a body having an outer shaft section for being received in the branch conduit and an inner flange section for opposing the liner within the main pipe. The fastener include one or more teeth that extend radially from the exterior of the shaft section. The teeth can be secured to the shaft section by deforming portions of the fitting body against the teeth. The flange section supports a gasket for sealing against the liner when the fitting is installed. The flange section can include a rim that maintains the gasket in the proper position.

A two-step threaded connection for steel pipe includes an intermediate seal and intermediate shoulders. A pin 2 has an inner male-threaded section 23 and an outer male-threaded section 26. A box 3 has an inner female-threaded section 33 and an outer female-threaded section 36. The pin 2 has a pin intermediate critical cross section PICCS located near an end of the first male-threaded section 23. The box 3 has a box critical cross section BCCS located near an end of the inner female-threaded section 33 and a box intermediate critical cross section BICCS located near an end of the outer female-threaded section 36. The pin 2 and the box 3 satisfy the following relationships:
PICCSA+BICCSA>BCCSA, and
0.70≤PICCSA/BICCSA≤0.95.

A two-step threaded connection for steel pipe includes an intermediate seal and intermediate shoulders. A pin 2 has an inner male-threaded section 23 and an outer male-threaded section 26. A box 3 has an inner female-threaded section 33 and an outer female-threaded section 36. The pin 2 has a pin intermediate critical cross section PICCS located near an end of the first male-threaded section 23. The box 3 has a box critical cross section BCCS located near an end of the inner female-threaded section 33 and a box intermediate critical cross section BICCS located near an end of the outer female-threaded section 36. The pin 2 and the box 3 satisfy the following relationships:
PICCSA+BICCSA>BCCSA, and
0.70≤PICCSA/BICCSA≤0.95.

The present invention describes a pipe sealing compound/adjunct lubricant used to prevent gas or liquid leaks when applied to pipe threads and other connections of the same. The compound relies on silicone oil lubricant(s) and one or more friction modifier(s), viscosity builder(s) and filler material(s). The compound contains a viscoelastic liquid that does not have a curing phase and is resistant to hardening and/or drying. The compound is chemically resistant to a wide variety of liquids and gases, is food safe and can withstand extreme high or low temperatures and precipitous temperature fluctuations. The compound has been found to exhibit an inverse pressure to leak rate phenomena.

The present invention describes a pipe sealing compound/adjunct lubricant used to prevent gas or liquid leaks when applied to pipe threads and other connections of the same. The compound relies on silicone oil lubricant(s) and one or more friction modifier(s), viscosity builder(s) and filler material(s). The compound contains a viscoelastic liquid that does not have a curing phase and is resistant to hardening and/or drying. The compound is chemically resistant to a wide variety of liquids and gases, is food safe and can withstand extreme high or low temperatures and precipitous temperature fluctuations. The compound has been found to exhibit an inverse pressure to leak rate phenomena.