INSULATING STRUCTURE FOR PIPE COUPLING

PROBLEM TO BE SOLVED: To ensure insulation and to facilitate parts control by inserting an insulating spacer between joint flanges, inserting flanged insulating sleeves reaching between the flanges into a flange bolt hole from opposite outer faces, and fastening them by bolts. SOLUTION: An insulating spacer 10 is inserted between the flanges 2 of a flange joint, the spacer 10 is made of hard rubber or a plastic, it has a shape with the diameter reaching the outer diameter of the flanges 2, and a bolt through hole 10a is bored at the position corresponding to the bolt through holes 2b of the flanges 2. Insulating sleeves 11 with flanges 9 are inserted into the bolt through holes 2b, the sleeves 11 are made of the same material as that of the spacer 10, and their lengths are set so that a gap 10b is provided in the through hole 10a of the spacer 10. O-rings 12 seal between flange opposite contact faces 2a. The flanges 9 concurrently serve as insulating washers, such an accident can be prevented that they are forgotten to be fitted, no insulating bolt is required, parts control is facilitated, and electric insulation can be ensured.