| 摘要 |
1,125,501. Protective coverings for boiler tubes. DOMINION BRIDGE CO. Ltd. 24 March, 1966 [17 Sept., 1965], No. 13064/66. Heading F4A. Metallic or ceramic protective thimbles 44 are fitted over the axially extending tubes 38 of a waste heat steam or hot water boiler (Figs. 1-3), immediately upstream of metallic or ceramic shielding plates 42 situated at the bend portions (40, Fig. 4) of the boiler tubes, to provide fairing surfaces and so prevent erosion of the tubes caused by the dust content in the waste gases. The thimbles 44 which may be in one or more longitudinal sections are formed with a rectangular base 52 dimensioned to be flush with the outer edge of the shield plates 42 and an annular top lip 50. The angle of the conical leading surface is 10 degrees or less and preferably between 5 and 6 degrees. The bases of adjacent thimbles around adjacent tubes abut one another. The thimbles may also be formed to fit rectangular tubes (Fig. 6), to fit tubes in tangent relationship (Figs. 10-12), or tubes interconnected by welded membranes (Figs. 7-9). In the latter cases the thimbles are formed as two half units attached to the tubes from opposed sides as by welding or brazing. Opposed sides of the base of the thimbles may be provided with the grooves (60, Fig. 14) to locate the chamfered edges (58) of the shield plates (42A) to prevent their outward movement whilst permitting sideways and downward movement due to thermal expansion.
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