Improvements relating to pressure vessels and to a method of forming pressure vesselshells with apertures provided with flanges or nipples

摘要

879,366. Making pressure vessels; forging. BABCOCK & WILCOX Ltd. Jan. 17, 1958 [Jan. 18, 1957], No. 1880/57. Classes 83 (2) and 83 (4). A method of providing a pressure vessel shell 1 with an apertured nipple or flange 2 projecting from its surface comprises forming in one face of the shell a recess 4, Fig. 3, having a diameter substantially equal to the intended diameter of the aperture, forming a hole 8 centrally of the recess, and hot forging the material surrounding the hole to form the flange or nipple 2. The recess 4 is formed by machining or forging, and the hole 8 is drilled during or after formation of the recess. After heating, the shell is supported by a female die 10 or is clamped between the die and a backing member, and is pierced by a male die 9 to form the nipple 2. A plurality of male and female dies may alternatively be used for the forging. The bottom surface 6 of the recess may alternatively be inclined, Fig. 2 (not shown). The end of the nipple may be subsequently trimmed to size. Specific proportions are given for the size of the recess 4 and the hole 8.