This is a self-restraining joint where thrust restraint is achieved by a specially designed gasket with embedded steel teeth. This performs the dual role of water sealing and restraining.
Express type mechanical joint is a bolted flexible joint used in DI fittings. The sealing is obtained by applying pressure to the gasket by a separate gland. The gland, when bolted with the pipe, exerts pressure on the sealing rubber gasket and makes the joint leak-proof.
