Expansion joint

A method for producing a tube for an evacuated tube transport system (ETT) comprising expansion joints and prefabricated tube segments,

• wherein the expansion joint comprises two annular rims to provide opposed first and second annular rims, each said annular rim provided on an outside perimeter of a respective said prefabricated tube segment, and an annular flexible and airtight sleeve for rendering the expansion joint airtight,
• wherein the sleeve comprises two annular bead sections, to provide first and second annular bead sections, connected by an annular flexible carcass, wherein each annular bead section comprises a bead wire, and wherein the bead sections are designed to airtightly co-operate with the two annular rims provided on the outside perimeter of the prefabricated tube segments,
• wherein the prefabricated tube segments are provided with the two annular rims which are each provided with a rim profile on the outside perimeter of each of the prefabricated tube segments, and wherein the rim profile is designed to cooperate with the two annular bead sections of the sleeve,
• wherein each annular rim is provided with the rim profile having a L-shape extending from a surface of the prefabricated tube segment and comprises a horizontal leg and an upstanding leg, wherein there is a rim top on top of the upstanding leg, a rim bead for receiving the bead section of the sleeve in a corner of the L-shape, and optionally a rim bead hump at an end of the horizontal leg of the L shape,
• wherein the upstanding leg of the first annular rim of the expansion joint is opposed to face the upstanding leg of the second annular rim of the expansion joint, whereby the rims of the expansion joint on the adjoining tube segments are mounted mirrored with respect to each other;
• wherein each upstanding leg has an inner wall proximal to the gap and an outer wall distal to the gap and a curved portion, comprising the rim top, extending from the inner wall to the outer wall to define a U-shape, wherein the outer wall provides a convex wall and a concave wall, the curved portion extending to the convex wall, the convex wall extending to the concave wall, and the concave wall extending to the horizontal leg;
• the method comprising the steps of:
• positioning two prefabricated tube segments to be adjoining with open ends of the prefabricated tube segments facing each other with a gap between the prefabricated tube segments;
• wherein each annular rim has a first end proximal to the gap and a second end distal to the gap, wherein each rim bead section is between the first end and the second end of each annular rim, wherein the first end proximal to the gap comprises the upstanding leg of the L shape, wherein the second end proximal to the gap comprises the end of the horizontal leg of the L shape;
• wherein the rim bead tops of the two annular rims are opposed and each have a circumference greater than an outer circumference of the prefabricated tube segment;
• wherein the rim second end distal to the gap has a circumference greater than the outer circumference of the prefabricated tube segment;
• optionally applying a bead lubricant and/or a sealant on the rims of the adjoining prefabricated tube segments;
• sliding the bead sections of the sleeve over the annular rims of the prefabricated tube segments, thereby flexibly connecting the prefabricated tube segments;
• wherein the first annular bead section is seated in the corner of the L-shape of the first annular rim to be contained entirely below the height of the rim top of the first annular rim, contact the concave wall of the first annular rim, and contact a lowest point of the rim bead of the first annular rim,
• wherein the annular flexible carcass of the sleeve extends from the first annular bead section then over the curved portion of the upstanding leg before, at, and after the rim top of the first annular rim and then across the gap, then over the curved portion of the upstanding leg before, at, and after the rim top of the second annular rim, and then to the second annular bead section,
• wherein the second annular bead section is seated in the corner of the L-shape of the second annular rim to be contained entirely below the height of the rim top of the second annular rim, contact the concave wall of the second annular rim, and contact a lowest point of the rim bead of the second annular rim;
• lowering an internal pressure in the tube to an operating pressure of an ETT-system, thereby sucking the annular flexible carcass of the sleeve inwardly between the gap between the two adjoining prefabricated tube segments and allowing the bead sections to become seated in the respective annular rims provided on the prefabricated tube segments and thereby providing an airtight seal;
• wherein the rims on the outside perimeter of the open ends of the tube segments are provided by means of welding a metal annular rim to the outer perimeter, and wherein the metal rim is provided with the rim profile.