A system for coupling a first pipe segment to a second pipe segment includes a pin end including a flange. The system includes a box end having a recess configured to receive the pin end, a face of the box end abutting the flange. The system includes a coupling assembly joining the first pipe segment to the second pipe segment including a split ring arranged proximate the flange and a sleeve, wherein threads of the sleeve engage first mating threads on the split ring and second mating threads on the box end.

A system for coupling a first pipe segment to a second pipe segment includes a pin end including a flange. The system includes a box end having a recess configured to receive the pin end, a face of the box end abutting the flange. The system includes a coupling assembly joining the first pipe segment to the second pipe segment including a split ring arranged proximate the flange and a sleeve, wherein threads of the sleeve engage first mating threads on the split ring and second mating threads on the box end.

A tube assembly (12) including an inner tube (13) having an outer thread (15), an outer tube (14) having an inner thread (16) engaging the outer thread (15), at least for securing an angular position between the inner tube (13) and the outer tube (14) is provided. Such a tube assembly should facilitate mounting and maintenance of a reverse osmosis system. To this end, the inner tube (13) includes at least an groove (17) on its outer surface and the outer tube (14) includes an recess (18) on its inner surface, wherein a blocking element is arranged in a space formed by the recess (18) and the groove (17) in overlapping relation with the groove (17) and the recess (18).

A tube assembly (12) including an inner tube (13) having an outer thread (15), an outer tube (14) having an inner thread (16) engaging the outer thread (15), at least for securing an angular position between the inner tube (13) and the outer tube (14) is provided. Such a tube assembly should facilitate mounting and maintenance of a reverse osmosis system. To this end, the inner tube (13) includes at least an groove (17) on its outer surface and the outer tube (14) includes an recess (18) on its inner surface, wherein a blocking element is arranged in a space formed by the recess (18) and the groove (17) in overlapping relation with the groove (17) and the recess (18).

A tubular connection comprising a longitudinal axis, a pin member comprising a distal pin end, a tapered pin thread having a constant pin taper angle α.sub.1 with respect to the longitudinal axis, and a pin sealing surface located between the pin thread and the distal pin end, and a box member comprising a distal box end, a box sealing surface, and a tapered box thread having a constant box taper angle β.sub.1 with respect to the longitudinal axis and located between the box sealing surface and the distal box end, and wherein the pin thread is configured to cooperate by make up with the box thread along a cooperating area, while having a radial thread interference between the pin thread and the box thread along at least part of the cooperating area, the pin sealing surface and the box sealing surface are configured to contact each other upon make-up in a sealing manner while forming a metal to metal seal, and the pin taper angle α.sub.1 is larger than the box taper angle β.sub.1.

A directly connected drill pipe applicable to extreme conditions includes a tool joint pin and a tool joint box, where an external pipe section is located on an external side of a threaded section of the tool joint pin, and an annular groove is formed between the external pipe section and the threaded section of the tool joint pin. An insertion section of the tool joint box can be inserted into the annular groove in a matched manner. A main shoulder of the tool joint pin is located at an end of the external pipe section, a main auxiliary shoulder of the tool joint pin is located on a bottom surface of the annular groove, and an auxiliary shoulder of the tool joint pin is located at a small end of the tool joint pin. The tool joint box has three corresponding shoulders which form a 3-stage sealing with the tool joint pin.

A directly connected drill pipe applicable to extreme conditions includes a tool joint pin and a tool joint box, where an external pipe section is located on an external side of a threaded section of the tool joint pin, and an annular groove is formed between the external pipe section and the threaded section of the tool joint pin. An insertion section of the tool joint box can be inserted into the annular groove in a matched manner. A main shoulder of the tool joint pin is located at an end of the external pipe section, a main auxiliary shoulder of the tool joint pin is located on a bottom surface of the annular groove, and an auxiliary shoulder of the tool joint pin is located at a small end of the tool joint pin. The tool joint box has three corresponding shoulders which form a 3-stage sealing with the tool joint pin.

A sealant material for sealing joints between male and female mating parts comprising: (a) an elongate flexible thread suitable for wrapping around at least one of the parts, and (b) a joint sealing composition comprising an anaerobically curable composition in solid form,
the flexible thread being coated with the anaerobically curable composition. This provides a reactive composition on the thread for sealing joints.

A sealant material for sealing joints between male and female mating parts comprising: (a) an elongate flexible thread suitable for wrapping around at least one of the parts, and (b) a joint sealing composition comprising an anaerobically curable composition in solid form,
the flexible thread being coated with the anaerobically curable composition. This provides a reactive composition on the thread for sealing joints.

An example fitting includes: a fitting body having counterbore, where the counterbore defines an annular shoulder within tire fitting body: a spring having a first end interfacing with the annular shoulder of the counterbore; and a seal carrier having: (i) a first end face interfacing with a second end of the spring, (ii) a second end face configured to interface with an internal surface of a port, such that the spring is configured to apply a biasing force on the seal carrier toward the internal surface of the port, (iii) a first annular groove on an exterior peripheral surface of the seal carrier, where the first annular groove is configured to have a radial seal disposed therein, and (iv) a second annular groove in the second end face, where the second annular groove is configured to have a face seal disposed therein.