FLANGED CONNECTIONS

摘要

A method of protecting a connection between two metal parts, which may be of similar or dissimilar metals, which connection is formed between flanged surfaces (2) on the two parts and which is clamped together by at least one backing flange (3) formed of a metal of different electrode potential from the metal of one of the parts in the connection which it would normally contact in making the connection, in which there is interposed between the backing flange and the metal of different electrode potential an annular insulating collar (5) of substantial L-shaped cross-section having axial and radial dimensions sufficient to prevent any contact between the backing flange and said metal and a material thickness within the range of 0.1 to 2.5 mm, said collar being formed of a non-crystalline, high temperature engineering thermo-plastics material having a continuous working temperature of at least 90C and being capable of withstanding the compressive forces in the connection without substantial creep and of isolating the two metals, thereby to prevent galvanic corrosion in the connection. Preferably the material of the collar has a thickness within the range of from .25 to 1.5 mm, a continuous working temperature resistance of at least 120C desirably at least 150C and can withstand a compressive force of at least 200 Kg/cm<2> without substantial creep. The material may be, for example, a polyether sulphone, a polysulphone, a polyetherimide or a polyphenylene sulphide.