Suggested Specification

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
or Contraction
from Mid-Point
Dead End
6" 5 degrees 3 degrees 8 degrees ± 2.4 inches 102,000 lbs
8" 5 degrees 3 degrees 8 degrees ± 2.4 inches 136,000 lbs
12" 5 degrees 3 degrees 8 degrees ± 2.4 inches 204,000 lbs
16" 5 degrees 2 degrees 7 degrees ± 2.4 inches 272,000 lbs
20" 4 degrees 2 degrees 6 degrees ± 2.4 inches 340,000 lbs
24" 4 degrees 2 degrees 6 degrees ± 2.4 inches 408,000 lbs

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 7.5 degrees or category M2 for sizes 6” – 12” and equal to or under 7.5 degrees or category M3 for sizes 16” and above.

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-M2-S1 per ISO 16134 for sizes 6” – 12” and A-M3-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.”