Field Flex-Ring Joint Pipe

Combining the sealing features of the time-proven Fastite joint, the AMERICAN Field Flex-Ring joint provides flexible, field adaptable restraint against endwise separation due to thrust and is easily assembled.

For the 4-inch, 6-inch, 8-inch and 12-inch sizes (small diameter), the AMERICAN Field Flex-Ring is a field adaptable restrained joint utilizing a grooved end and a corrosion-resistant, high-strength, low-alloy (HSLA) steel ring, simulating a weld ring. The restraint is provided by a wedging action that acts between the steel ring and a yellow painted ductile iron split Flex-Ring. Once the grooved fabricated end is created and the steel ring is installed, the Field-Flex Ring spigot end behaves identically to the shop fabricated Flex-Ring spigot end. After the spigot end of the Field Flex-Ring pipe is assembled into the Flex-Ring bell, the split Flex-Ring is inserted and springs into the socket locking groove. The Flex-Ring is securely positioned behind the bolt-on field ring and in the socket locking groove on the inside of the pipe bell providing the flexible restraint.

The small diameter AMERICAN Field Flex-Ring is designed to restrain joints with the same allowable working pressures and deflection capabilities as the standard Flex-Ring Joint. Small diameter Field Flex-Rings may be used with a minimum 53 thickness class ductile iron pipe with a maximum working pressure of 350 psi. Restrained joints using the AMERICAN Field Flex-Ring have been factory tested to withstand dead end thrust resulting from more than twice the rated working pressure.

For larger diameters, the AMERICAN Field Flex-Ring with black-toothed gripping segments is available. This method of restraining AMERICAN 14-inch to 36-inch ductile iron Flex- Ring pipe and fittings is an easy, totally boltless and glandless way of restraining field connections, which does not require a factory or field weldment. Where field cuts are anticipated, the Field Flex-Ring may be used to restrain joints with any suitable ductile iron plain end.

The patented large diameter AMERICAN Field Flex-Ring is designed to restrain joints with the same allowable working pressures and deflection capabilities as the shop fabricated Flex-Ring joint. Large diameter Field Flex-Rings may be used with any standard pressure class of ductile iron pipe with an allowable working pressure equal to that of the pipe class, or a maximum of 350 psi in the 14-inch to 24-inch sizes and 250 psi in the 30-inch and 36-inch sizes. 

Restrained joints using the large diameter Field Flex-Ring have been factory tested to withstand dead-end thrust resulting from more than twice the rated working pressure. The restraint is provided by the wedging action of heat-treated high-strength ductile iron segments. The segments have a wedge-shaped cross-section with gripping teeth on the inner surface. The ductile iron segments are held in the proper position for assembly by a rubber backing ring. This rubber backing ring is compressed during assembly to ensure that the restraining segments are held firmly in place against the socket wedging surface and spigot. The positioning and compressive force exerted by the backing ring on the restraining segments result in dependable gripping of the spigot when thrust is applied.

For both large and small diameter applications where field restraint is required, the AMERICAN Field Flex-Ring joint provides a robust, cost effective, field adaptable solution.   

U.S. Patent No. 5,197,768