The AMERICAN Earthquake Joint System (Patent 10,436,367) combines the rugged, tough, and time-proven deflection performance of AMERICAN’s Flex-Ring restrained joint pipe with the capacity to expand and contract.
The system is built around a ductile iron Earthquake System casting that features in its design an extended socket depth allowing the specially placed Flex-Ring weld ring an expansive range of motion.
The ductile iron Earthquake System casting and Flex-Ring connecting piece arrive at the jobsite pre-assembled by our professional staff at our manufacturing plant. The extended socket receives a special Flex-Ring spigot end with a specially located restraining ring. The pre-assembled Earthquake System spigot has a double stripe, one showing full insertion and the other mid-point insertion. The illustration below shows the joint installed in the fully extended position, such that both assembly stripes are fully visible.
Pre-assembly means the on-site contractor needs to assemble only the familiar and conventional Flex-Ring joint. In this application, the Flex-Ring spigot on the ductile iron Earthquake System casting is red in color and machined instead of welded. Conventionally, it’s a Flex-Ring joint and is assembled in the field in the same manner.
The AMERICAN Earthquake System joint may be assembled in the fully contracted position, allowing for maximum expansion; it may be assembled in the mid-point position, allowing for both joint expansion and contraction; or it may be assembled in the fully extended position, allowing for maximum joint contraction.
The more common is the mid-point position, which allows for both expansion and contraction during a seismic event.
After assembly, the AMERICAN Earthquake Joint System can expand and contract longitudinally and deflect at both joints. With deflection from the conventional Flex-Ring joint and additional deflection from the extended socket Flex-Ring joint, the assembly provides 8 degrees deflection for 6”, 8” and 12”; 7 degrees for 16”; 6 degrees for 20” and 24”; and 5 degrees for 30"; as well as 2.4 inches of either expansion or contraction for all diameters. If assembled in the fully contracted or fully extended position, 4.8 inches of one-way longitudinal differential is available for all diameters.
The year was 1989. The place was Anchorage, Alaska. The project was the installation of a gravity sewer line beneath Campbell Lake while it was drained for dam repairs. While this type of project and installation is unique in itself, the pipeline’s performance during a magnitude 7.1 earthquake more than 30 years after it was installed is equally remarkable.
