GB734341A - Improvements relating to pipe lines for high pressure high temperature fluid - Google Patents

Abstract

734,341. Pipe joints. METROPOLITANVICKERS ELECTRICAL CO., Ltd. April 17, 1952 [March 19, 1951], No. 6536/51. Class 99 (1). [Also in Group XXII] In a pipe-line for conveying fluid at very high temperatures and pressures, comprising straight lengths of wrought metal piping joined by short bends or other junction pieces welded between the straight lengths by circumferential butt welds, the wall thickness of the straight lengths is determined in accordance with the temperature and pressure of the fluid to be piped without additions to allow for the reduced strength of the welds or for thinning by bending, while at least in the vicinity of each weld between a junction piece and a straight length the wall of the former is thicker than that of the latter so as to exert a supporting influence on the weld such that the circumferential stress therein is not greater than the product of the weld factor, i.e. the ratio of weld strength to pipe strength, and the general circumferential stress in the straight lengths. In Fig. 1, a cast bend 3 welded at 1a, 2a, to straight lengths 1, 2, has thickened wall portions 3a forming supports for the welds. In Fig. 1A (not shown) the weld conforms with a taper at the end of the bend. A backing ring 32, Fig. 6, may be used to register the pipes before welding and forms a base for the groove to receive the welding metal ; the backing ring may be flush with the inside of the pipe, or, instead of using a separate ring, an extension of one pipe may spigot into the other pipe. Where extra support is required to allow for inefficiency of welds made on site, increased wall thickness is provided on both sides of the weld which may then be of reduced thickness. As shown in Fig. 6, a collar 29 of greater thickness than that of the pipes is shop welded at 28 to a pipe 27, and is site welded at 31 to a second pipe 30. In Fig. 8 a collar 43 is shop welded to a pipe 41 and is site welded to a collar 42 shop welded to a pipe 40. The collars are held together, for site welding, by flange rings 45, 46 clamped against shoulders on the collars by bolts 47, 48. To facilitate removal, the rings are split diametrically and bolted together.