A low-pressure tubular system, for instance a vacuum tube train transportation system, comprising: a multitude of interconnected tube sections having a longitudinal axis; wherein each of the tube sections comprise a central part and two outer end parts; wherein the tubular system is configured to maintain a low-pressure environment within the connected tube sections; wherein the system further comprises a multitude of expansion joints connecting the tube sections; wherein each of the expansion joints comprises a sleeve made of a flexible sheet material and comprising a ring shaped endless central part and two ring shaped endless outer end parts; and wherein each of the outer end parts of the expansion joints are arranged to extend coaxial with an adjacent tube section and surround and sealingly engage the outer end part of said adjacent tube section.

A tubular string having a box end and pin end coupled to one another with a threaded attachment and a coupling assembly. The coupling assembly includes an annular outer thrust ring having an axial end abutting a shoulder on a terminal end of the box end. Included with the coupling assembly is an inner thrust ring, which is also annular, and which has an end that axially abuts a shoulder formed along an outer surface of the pin end. An alternate type of the inner thrust ring is made up of two separate semi-circular members that circumscribe the pin end when positioned in the recess so their arcuate ends adjoin. The inner thrust ring inserts into the outer thrust ring, and has a radial surface on its outer circumference that lands on a shoulder formed along an inner circumference of the outer thrust ring.

An expansion joint includes: an outer tube including first and second ends and extending therebetween, the outer tube including first and second flanges, the first being located at the first end, the second being located at the second end and connectable to a downstream pipe; an inner tube including third and fourth ends and extending therebetween, the inner tube being located inside the outer and including third and middle flanges, the third flange being located at the third end and connectable to the upstream pipe, the middle flange being located at a middle portion between the third and fourth ends; and a closure including an outer peripheral portion connected to the first flange, an inner peripheral portion connected to the middle flange, and an elastic portion connecting the outer and inner peripheral portions. The first end is spaced from the third and located between the third and fourth ends.

A grooved-ended resilient expansion joint is disclosed. The expansion joint has a resilient expansion member with a central resilient portion and two resilient axially disposed cylindrical ends. Each cylindrical end has a radially outwardly raised distal cylindrical gasket portion with at least one inside shoulder having an inner diameter sized substantially the same as an outer diameter of a pipe to be joined. A pair of pre-assembled pipe couplings are provided for joining the expansion joint to a pair groove-ended pipe segments without disassembling the coupling.

A flexible pipe fitting for joining a first length of pipe to a second length of pipe at an arbitrary angle is provided. The apparatus includes a primary fitting having a substantially circular opening at a first end thereof for receiving an end of a first length of pipe, and an enlarged opening at a second end thereof for receiving a first flexible coupling member. The first flexible coupling member includes an outer wall having an outer surface engaging an inner surface of the enlarged opening, and an inner wall having a lower end connected to a lower end of the outer wall. The inner wall further includes a substantially circular opening therein for receiving a second, rigid member. The inner surface of the second, rigid member is configured to receive an end of the second length of pipe. The enlarged opening in the primary fitting is preferably fish-mouth shaped, or alternatively, cone shaped. Adhesive, such as PVC cement may be used to bond the various fittings, and lengths of pipe together to form a sealed joint.

A grooved-ended resilient expansion joint is disclosed. The expansion joint has a resilient expansion member with a central resilient portion and two resilient axially disposed cylindrical ends. Each cylindrical end has a radially outwardly raised distal cylindrical gasket portion with at least one inside shoulder having an inner diameter sized substantially the same as an outer diameter of a pipe to be joined. Each cylindrical end also has a neck portion between the central portion and the gasket portion that is sized to receive a grooved-ended pipe nipple.

A grooved-ended resilient expansion joint is disclosed. The expansion joint has a resilient expansion member with a central resilient portion and two resilient axially disposed cylindrical ends. Each cylindrical end has a radially outwardly raised distal cylindrical gasket portion with at least one inside shoulder having an inner diameter sized substantially the same as an outer diameter of a pipe to be joined. Each cylindrical end also has a neck portion between the central portion and the gasket portion that is sized to receive a grooved-ended pipe nipple.

A compensator arrangement comprising a first fixing unit, a second fixing unit, and an intermediate flexible member removably arranged between the first fixing unit and the second fixing unit and comprising a main body, a first radial end flange and a second radial end flange, wherein the first fixing unit comprises a first connecting member having a first connecting body and a first fixing flange having a plurality of through-holes, a first counter ring, a first clamping ring and a first clamping device for releasably clamping the first radial end flange.

A compensator arrangement comprising a first fixing unit, a second fixing unit, and an intermediate flexible member removably arranged between the first fixing unit and the second fixing unit and comprising a main body, a first radial end flange and a second radial end flange, wherein the first fixing unit comprises a first connecting member having a first connecting body and a first fixing flange having a plurality of through-holes, a first counter ring, a first clamping ring and a first clamping device for releasably clamping the first radial end flange.

A grooved-ended resilient expansion joint is disclosed. The expansion joint has a resilient expansion member with a central resilient portion and two resilient axially disposed cylindrical ends. Each cylindrical end has a radially outwardly raised distal cylindrical gasket portion with at least one inside shoulder having an inner diameter sized substantially the same as an outer diameter of a pipe to be joined. A pair of pre-assembled pipe couplings are provided for joining the expansion joint to a pair grooved-ended pipe segments without disassembling the coupling.