Seismic and Storm-Resistant Ductile Iron Pipe, Valve, and Hydrant System - Part 3

This is the third of six postings in a series and the seventh publication will include the entire presentation.

A much-earlier version of this content which did not include diameters larger than 12-inch nor any information about storm resilience was presented at an ASCE Pipelines conference and an AWWA infrastructure conference. Since those presentations, the size range has been expanded and testing has been completed. An application to storm environments has also been recognized.

Today, we start with a review of the testing of this joint system and begin to examine the valve and hydrant portions of it.

Rigorous Testing at Cornell University

The gold standard for 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 and led by Dr. Brad Wham, 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

Quoting the primary conclusions of the Cornell analysis of AMERICAN’s system:

“The four-joint pipeline used in the large-scale split-basin test was able to accommodate at least 21.5 in. (461 mm) of axial extension, corresponding to an average tensile strain of 4.4% along the pipeline. Such extension is large enough to accommodate the great majority (over 99%) of liquefaction-induced lateral ground strains measured by high resolution LiDAR after each of four major earthquakes during the recent Canterbury Earthquake Sequence (CES) in Christchurch, NZ.”

“The fault rupture test confirms that the ductile iron pipes equipped with the AMERICAN Earthquake Joint Systems are able to sustain without leakage large levels of ground deformation through axial displacement and deflection under full-scale conditions of abrupt ground rupture.” (Pariya-Ekkasut, January 2017)

While the pipe is not visible because it is buried in the box on the left side and ready for testing, the Cornell lab is shown in Figure 8.

Figure 8. AMERICAN earthquake joint pipe buried and ready for testing in Cornell’s seismic testing lab.

Let’s look now at the joint system with respect to the valve and hydrant assembly, then with respect to the pipe assembly, and finally as an integrated system.

The AMERICAN Flow Control Earthquake Joint Fire Hydrant System

Prior to the development of traditional water systems, fire protection was available primarily from rivers and lakes and in some cases, man-made basins and water storage tanks. From an historical perspective, the earliest water mains in the United States can be traced back to 1652 in Boston, Massachusetts. The waterlines of that day were hollowed out logs. In a fire emergency, the wooden pipe was excavated and a trench was formed. A hole was bored in the log, allowing the trench to fill with water. The water that collected around the pipe was then transported by a bucket brigade and poured directly on the fire. Afterwards, a plug was placed in the wooden pipe. The location of the plug was marked, so that it could be removed in the event of another emergency. The plug was referred to as a “fire plug.” a reference is common to the utility industry even today. 

Over time, water distribution systems began to use cast iron pipe, and the fire plug evolved into cast iron stand pipes. In the mid-1800s, improvements were made to the standpipe to include a ball and rod type mechanism that could be pushed downward into the pipe allowing water to flow out. These early designs were the precursor to the modern-day fire hydrant. 

Much has changed over the years resulting in the fire hydrant assemblies we see today. The most common type of hydrant is designed to handle a broad range of climates and traffic impact without substantial loss of water. This is known as dry-barrel hydrant design and includes a valve in the base of the hydrant. An AMERICAN Flow Control hydrant assembly is shown in Figure 9.

Figure 9. A traditional modern-day hydrant lead with isolation gate valve and valve box.

Today’s dry-barrel hydrants are configured with a drain mechanism that allows the standpipe to empty after use. A less common fire hydrant is also available with above ground valves, and they are known as wet-barrel hydrants. Wet-barrel hydrants are primarily found only in the southern and central areas of California. The main difference between the two applications is the location of the valve. In each case a hydrant should always be equipped with a gate valve for isolation of the hydrant branch. 

In a seismic event, some of the first casualties to the infrastructure are the utilities. Failed electrical and gas lines are the source of fires and can be responsible for significant loss of life and property, as well as added infrastructure damage. Unfortunately, the water lines that make up the fire protection systems are typically also compromised. Because of this need, AMERICAN Flow Control became the first in the United States to offer a seismic resistant fire hydrant lead. In this offering, the EQ joint from AMERICAN has been integrated into the base of a traditional fire hydrant. This feature allows for +/- 2.4 inches of longitudinal extension and in total more than 13 degrees of deflection of the inlet piping, all while having the ability to withstand more than 100,000 pounds of thrust. 

Next week, we will complete our review of the hydrant portion of the system. Until then, Like, Share, Comment, and feel free to contact me.