In order for a coupling to perform well it needs to maintain an adequate sealing pressure between the coupling and the pipe.  This is necessary to resist internal and external hydrostatic pressue as well as root intrusion.  With VIPSeal, this is achieved by a relatively simple system of applying pressure to the elsatomeric sleeve through the use of tension bands.  The use of a heavy duty single or multiple worm drive allows the radial sealing force to be equally spread around the circumference ensuring optimum sealing performance.