| 摘要 |
<p>1390873 Metal pipes PRELOAD TECHNOLOGY Inc 25 July 1973 [29 Sept 1972] 35533/73 Heading F2P A pipe suitable for low temperature fluid comprises a metal conduit 26, an outer concrete pipe 28 surrounding said conduit and defining an annular space 36 therewith and means rigidly connected to the outside of the conduit and abutting or being capable of abutting the end of said outer concrete pipe to transfer compressive stresses thereto upon thermal contraction of said conduit. In the arrangement shown two conduits 26, 76 welded at 85 each have an outer concrete pipe 28, 78 spaced from the conduits by spacers 30, 80. A flange 40 is rigidly secured to conduit 26 and backed by stiffeners 42. On each side of flange 40 annular insulating rings 44, 46 (e.g. of p.v.c.) are positioned in abutting relationship with flanged ends of the concrete pipes 28, 78. Initially there may be a small space between, the insulating rings to take up some of the contraction of the pipes 26, 76 before the rings contact the flanges. The annular space between the conduits and the pipes may be filled with an insulating material, e.g. perlite. In a further embodiment (Fig. 5, not shown) a bellows type expansion joint is incorporated between the two conduits. In this embodiment also the concrete pipes are prestressed with circumferential and longitudinal wires. The concrete pipes may also incorporate steel shells within their walls to prevent seepage of fluids through the walls.</p> |
