GB661174A - Improvements in or relating to floating roof for floating roof liquid storage tanksand methods of erecting the floating roofs - Google Patents

Abstract

661,174. Floating roof tanks. CHICAGO BRIDGE & IRON CO. Dec. 2, 1947 [June 26, 1946; May 29, 1947] 31799/47 and 31800/47. Class 69 (i). A circular floating roof 11 for a liquid storage tank 10 comprises an annular pontoon 13 beneath the outer edge of a deck 14, an inner annular pontoon 16, a central sump 15 provided with a drain pipe 17 and surrounded by a ring girder 18, and inner and outer groups 19, 20 of channel-section radial rafters secured at their ends to the pontoons and to the ring girder. The sump 15 and pontoon 16 may be replaced by a central pontoon. The deck 14 slopes uniformly inwards and downwards, it is built up from sheet metal plates so as to be substantially inflexible, and is secured to the open tops of the pontoons and to the entire length of most or all of the rafters. Small braces 21 are welded to the deck and their bevelled ends 22 are welded to the inside walls of the pontoons. The roof and side walls of the tank are connected by a flexible sealing member 128. The inner and outer gas spaces beneath the roof are connected by a vent pipe 23 in the pontoon 16, and an emergency vent pipe 24 or 124 extends upwards and outwards through the pontoon 13. The vent pipe 124 has a baffle plate 129 and escaping vapour passes in opposite directions around the roof to a diametrically-opposite vent 125 open to the atmosphere. The roof may be assembled upon the bottom of the tank without using temporary erection framing.