No-Hub Coupling

A combination of in-field experience and testing has revealed that there may be a better way to install no-hub couplings, improving the quality of the seal and decreasing the chance of leaks and other system failures.

The improvement comes from the sequence in which the clamp bolts are tightened.

Testing has revealed that if the bolts on the smaller of the two pipe ends being joined are tightened first, then the larger end tightened, the clamp bands compress the underlying shield in such a way that a tighter seal is produced.

"Plumbers have quibbled over the best way to install no-hub couplings for a long time," said AB&I's plumbing division manager, Gary Wickham, "but this new testing should put the arguments to rest."

Plumbers are encouraged to follow these new installation instructions to maximize the integrity of the coupling joints. A properly-calibrated torque wrench, preset to 80 inch-pounds, should always be used.

Instructions

1. Pipe ends should be cut square. Place the neoprene gasket on the end of one pipe and the stainless steel clamp assembly on the other end of the pipe or fitting to be joined.

2. Firmly seat both ends of the pipe/fittings against the internally molded shoulder in the center of the gasket.

3. Slide the clamp assembly into position, centered over the gasket.

4. Couplings in 1-1/2+, 2+, 3+ and 4+ sizes are three inches wide and have four sealing bands. Tighten bands to 80 inch-lbs in the following sequence (starting on the side of the joint with the smallest diameter): 2,1 - 2,1 - 3,4 - 3,4 - 2,1 - 3,4.

5. Couplings in 5+, 6+, 8+, 10+ sizes are four inches wide and have six sealing bands. Tighten bands to 80 inch-lbs in the following sequence (starting on the side with the smallest diameter):
3,2,1 - 3,2,1-3,2,1 - 4,5,6 - 4,5,6 - 4,5,6.