Iron Pipe Joint Development down through the Years - Part 5 of 5

This is an edited version of a presentation and paper at the 2017 American Society of Civil Engineers' Pipelines conference. This is the fifth and final installment in a series of brief articles; and next week, they will be combined and published in their entirety.  Today, we reach the pinnacle of joint development with the AMERICAN earthquake joint system for pipe, valves, and hydrants.

AMERICAN Earthquake Joint System

In the past few years, the water utility industry has focused on becoming better prepared for seismic threats. At the 2014 ASCE Pipelines conference in Portland, Oregon, Mark Knudson of Tualatin Valley Water District challenged the industry to prepare for a major seismic event. (ASCE Pipelines Conference Program, 2014) Since then, many utilities have begun hardening their networks and adding seismic resiliency to their design criteria. 

At the 2016 ASCE Pipelines conference and 2017 AWWA Water Infrastructure conference, I presented a more lengthy paper than this article on an earthquake joint system for ductile iron pipe, valves, and fire hydrants. (Gaston and Ratcliffe, 2016) In the near future, I'll publish that here in its entirety, too. 

The AMERICAN earthquake-resistant joint system provides 8, 7, or 6 - degrees of deflection in all radial directions and a range of motion of 4.8 inches longitudinal expansion or contraction - a remarkable combination of joint performance attributes. End-wise strength of this joint assembly ranges from 102,000 pounds for 6-inch to 408,000 pounds for 24-inch. The three-piece assembly is shown in Figure 12.

Figure 12. Ductile iron pipe earthquake joint assembly. (www.american-usa.com).

This performance is accomplished by using a central (red in color) earthquake casting with the conventional Flex-Ring joint on one end having 5 or 4 - degrees deflection and a deepened bell on the other end allowing the 4.8-inch longitudinal range-of-motion and providing 3 or 2 - degrees deflection. The deepened bell is pre-assembled so that only the familiar conventional Flex-Ring joint is assembled in the field. As is typical for joint performance, the deflection capacity reduces as the diameter increases.

Rigorous Testing at Cornell University

The gold standard for certifying performance and design of seismic products in the United States is the Geotechnical Lifelines Large Scale Testing Facility at Cornell University in Ithaca, New York. In early 2017, the AMERICAN Earthquake Joint System was tested in that lab including “… deflection to failure; axial, tensile, and compressive load to failure; and a full-scale earthquake fault simulation. Results of the testing prove the AMERICAN earthquake resistant joint meets requirements for the following ratings under ISO16134 – “Earthquake- and Subsidence-Resistant Design of Ductile Iron Pipelines:”

• Expansion and contraction performance: S-1 (+/- 1% or more), the highest category
• Slip-out resistance: A, the highest category
• Joint deflection angle: M-2 (between 7.5° to 15°), the second highest category

If you'd like more information on the testing protocol and results, let me know, and I'll be happy to provide it.

Fire Hydrant Assemblies are Included

Unique to AMERICAN's seismic system, the AFC B-84-B fire hydrant and isolation gate valve as shown in Figure 13 are part of this system resulting in fire protection when needed following a seismic event. After all, a post-quake fire can be more devastating than the quake itself.

Figure 13. The American Flow Control B-84-B hydrant and gate valve with seismic joints.   

An animated video of this system in motion is available on our website.

Conclusion

While the water industry in general and the iron pipe industry in particular may appear to those outside of it to be mature and staid, today’s ductile iron pipe joints employ the latest design and on-going innovative attributes to provide secure and dependable joint and restraint performance for our nation's water, wastewater, and fire protection infrastructure, and AMERICAN is the leader in that arena. The history of iron pipe joint development chronicled here is one of increasing performance, efficiency, and consistent innovation. 

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