In fact, the double-sphere rubber expansion joint is distinguished from the single-sphere rubber expansion joint in the outer shape, and its installation length is longer than that of the single-sphere rubber soft joint, which solves the problem of short installation size of the rubber expansion joint . In the case of installing a rubber expansion joint with a long length, the double-sphere rubber expansion joint can be used, but it is forbidden to install it beyond the offset limit when installing it. The manufacturing method of the double-sphere rubber expansion joint is similar to that of the single-sphere rubber soft joint, which is composed of the inner surface rubber, the curtain layer and the cushion belt, and then it is loosely sleeved with the metal flange or the parallel connector after being mixed into shape. Because the length of the double-sphere rubber expansion joint is very long, part of the key to compression is the protruding part in the middle, so the double-sphere rubber soft joint can not bear the pressure as much as the single-sphere rubber soft joint.                Generally, the small diameter of the double-sphere rubber expansion joint is very high, which can reach 1.6Mpa, while the large-caliber double-sphere rubber soft joint can achieve 1.0Mpa with high energy. When connecting with mechanical equipment or pipelines, the double-sphere rubber expansion joint can reduce the noise better.