GB877277A - Improvements in or relating to seals for the closures of pressure vessels - Google Patents

Abstract

877,277. Covers for resisting fluid pressure. BABCOCK & WILCOX CO. Jan 27, 1959 [Jan. 30, 1958], No. 2986/59. Class 123(1) A pressure vessel comprises a cylindrical container 10 having its upper end thickened to form an inwardly projecting flange 25 and a closure member 12 consisting of a hemispherical part with a thicker cylindrical flange 16 the cooperating walls 20, 21 of the flanges 25, 16, which are clamped into sealing engagement by a circle of bolts 36, being continued outwardly respectively by walls 52 and 31, 54 defining an encircling recess 38 which is sealed, to withstand the pressure of the vessel, by a flexible metal band 40. The upper and lower edges of the band 40, which is of arcuate section and fits snugly within the recess 38, are welded to the recess walls 54, 52 which, with the walls 31, 21 and 20 respectively, are covered by corrosion-resistant cladding 13, 14 which is used to line the internal surfaces of the closure member 12 and the container 10. The bolts 36, extend through circumferentially spaced holes 34 in the flange 16 across an annular space 50 between walls 22, 23 which diverge outwardly from the walls 52, 54 respectively, and screw into corresponding threaded holes 35 in the flange 25. After the sealing band 40 has been fitted and the closure member 12 has been bolted on to the container, the bolts are removed, one at a time, to facilitate welding. Drainage ducts 47, 49, leading respectively from the space 46 on the wall 20 between radially spaced grooves containing compressible gaskets 44, 45 and the part 48 of the recess 38 enclosed by the band 40, communicate with leakage containers, not shown, located outside the container 10. In a modification the recess 38 is of arcuate cross-section and is formed in the co-operating outer thickened edges of the cladding on the walls 20, 21. In both of the embodiments the channels 47, 49, as well as the grooves 44, 45 for the gaskets 44, 45 could be formed in the closure member 12 and one channel or groove could be provided in the member 12 and the other in the container 10. The gaskets 44, 45 could also each lodge in two corresponding shallow grooves formed one in the container 10 and the other in the closure member 12. Alternatively the inner gasket groove 44 may be omitted or, the grooves may be dispensed with altogether. The space between the band 40 and the outermost gasket 44 may be pressurized by a fluid introduced through the channel 49 at a pressure slightly greater than that within the vessel 10. A second channel 49 could be provided on the opposite side of the container 10 so that one channel could act as an inlet and the other as an outlet for a cleansing fluid after the recess has been depressurized prior to the removal of the band 40.