Pipe Fitting System Provides Connection, Restraint
The AquaGrip System, available from Mueller Co., provides both a compression connection and restraint system in one installation package. It is designed to be used on DI, PVC, and PE pipe without changing any components and without the need for "add-on" style restraints.
The AquaGrip features a pressure responsive sealing system and visual indication that the connection is properly tightened. These features help assure a leak-tight seal, even after pipe wall relaxation.
As the bolts are tightened, the end ring forces the metal grip ring to compress. The teeth of the grip ring bite into the pipe OD, providing a uniform, positive circumferential restraint around the pipe to prevent pullout caused by ground movement or pressure surges.
At the same time, the end ring pushes the intermediate ring toward the bell end of the connection, mechanically forcing the double O-ring seal into compression. In addition, integral channels are built into the connection to allow line pressure behind the O-ring, using hydrostatic pressure to assist in providing a positive seal.
Finally, unique break-nuts shear at the correct input torque. This feature visually shows when the connection is properly tightened to both seal and restrain the pipe. After the break-nut is sheared, a full size nut remains for removal in the future if required.
The AquaGrip System is "stab-fit" and no special tools or torquing are required. A six inch connection uses four bolts compared to six bolts for a standard M.J. connection and nine bolts for the typical restraint gland. The fittings can be used on DI, PVC, and PE pipe. Use of PE pipe does not require a special support liner (up to DR17).
The fittings work with plain end pipe and can be installed in wet conditions and even under water.
The AquaGrip system has a maximum working pressure up to 250 psig. It is designed to meet the performance requirements of ASTM F1674 and UL 1285 for PVC; WIS 4-24-01 Type 2 and ISO 14236.2 for polyethylene; UL 194 for ductile iron; and FM Class Number 1620 for all three type pipes. "In-line" couplings, mechanical joint transition fittings and flanged coupling adapters are also available as part of the AquaGrip Connection System package.