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.
As required on the project plans and in these specifications, in high-risk areas subject to earthquakes, a ductile iron system shall be provided that delivers joint deflection and longitudinal expansion or contraction. This system shall be the AMERICAN Earthquake Joint System or a system equal to or exceeding each of these performance criteria:
Diameter | Pipe Joint | Casting | Combined | Expansion | Dead End | ISO 16134 |
|---|---|---|---|---|---|---|
6" | 5 degrees | 3 degrees | 8 degrees | ± 1.00% (2.4 inches) | 102,000 lbs | A,M1,S1 |
8" | 5 degrees | 3 degrees | 8 degrees | ± 1.00% (2.4 inches) | 136,000 lbs | A,M1,S1 |
12" | 5 degrees | 3 degrees | 8 degrees | ± 1.00% (2.4 inches) | 204,000 lbs | A,M1,S1 |
16" | 3.75 degrees | 3.25 degrees | 7 degrees | ± 1.00% (2.4 inches) | 272,000 lbs | A,M2,S1 |
20" | 3.50 degrees | 2.50 degrees | 6 degrees | ± 1.00% (2.4 inches) | 340,000 lbs | A,M2,S1 |
24" | 3 degrees | 3 degrees | 6 degrees | ± 1.00% (2.4 inches) | 408,000 lbs | A,M2,S1 |
30" | 2.5 degrees | 2.5 degrees | 5 degrees | ± 1.00% (2.4 inches) | 510,000lbs | A,M2,S1 |
The ductile iron earthquake resistant pipe shall meet all applicable requirements of AWWA C150 (design), AWWA C151 (manufacture), AWWA C104 (lining), C111 (joints), AWWA C153 (fittings), AWWA C105 (polyethylene encasement), and AWWA C600 (installation). The ductile iron pipe shall be sized in inches.
The piping shall meet defined classifications detailed below as shown in ISO 16134 Earthquake Resistant Ductile Iron Pipe and Subsidence-Resistant Design. The seismic design shall be verified by an independent seismic lab such as Cornell University or an owner-approved alternative.
1. All ductile iron pipe and fittings joints shall meet or exceed 3dKN pull out strength or category A.
2. Designated Earthquake System piping shall meet or exceed a minimum deflection of 8 degrees for category M1 for sizes 6” – 12”, between 4 degrees to 8 degrees for category M2 for 16", and between 3.5 degrees to 7 degrees for category M2 for sizes 20" and above, whether in the mid-point, fully inserted, or fully extended positions..
3. Designated ductile iron Earthquake System piping will have a minimum strain relief of plus or minus 1% or category S1.
As a designation, the minimum requirements would be A-M1-S1 per ISO 16134 for sizes 6” – 12” and A-M2-S1 for sizes 16” and above, unless otherwise shown on plans and specifications.
The network of ductile iron pipe connected to the Earthquake Joint System shall have the exterior of the pipe coated with a layer of arc-sprayed zinc. The mass of the zinc applied shall be a minimum of 200 g/m2 of pipe surface area and the coating system shall conform in every respect to ISO 8179-1, "Ductile Iron Pipes – External Zinc-Based Coating – Part 1: Metallic Zinc with Finishing Layer,” second edition 2004-06-01. The zinc shall have a top coat of approved materials. (Component pieces and field touch up may require the use of a zinc-rich coating 85% zinc per ISO-8179-part 2)
The Earthquake System piping will be installed in the fully open, fully closed, or mid-point position per design criteria. To facilitate determining field joint alignment, the expansion spigot in the assembly shall have a minimum of two assembly stripes – one indicating fully contracted and one indicating the mid-point of extension. Full extension can be achieved by pulling the completed joint out until the joint stops movement.
In addition, the connected network of ductile iron pipe shall be encased in 8 mil V-Bio polyethylene encasement meeting the requirements of AWWA C105 concerning both materials and installation.
The pipeline will be installed with a locator tape that identifies the buried line as an earthquake resistant pipeline. The tape will be a minimum 2 inches in width and red in color with the wording “Earthquake Resistant Pipeline Below.”
