Streamline - Summer 2016 - (Page 36)

When and How to Use Piping Restraints Piping restraints play an essential role in ensuring safe water and wastewater system operations. However, it's important to evaluate criteria such as local soil conditions, materials, existing infrastructure, deflection, seismic activity and cost to determine the most appropriate restraint to use. BY DOUG RISEDEN piping stays connected and help prevent costly repairs that can shut down a water or wastewater system. Mechanical-joint piping connections such as 45s, 90s, end caps, and hydrant connections are common points of restraint as well as connections within wells, wastewater lift stations and treatment plants. RESTRAINING TECHNIQUES ENSURE Restraining inline piping has become so common that the practice is often a matter of standard procedure among city or project engineers. Instead of using restraints for specific applications, some engineers use restraints throughout entire systems. Adding restraints in this manner can be expensive and increase project costs significantly. It's worth examining what criteria should be followed for restraining pipe connections and which techniques to use within particular conditions and environments. Criteria for restraining pipe Although engineers typically decide when and how to restrain pipes, utility managers can and should be part of the process. Once a piping system is A Thrust block 36 S T R E A M L I N E * S u m m e r 2 0 1 6 completed, it's in their hands to ensure the system works properly and to make repairs, so it's essential to include their input. The first things to examine are the factors that may affect the chances of pipe movement and separation. Important criteria to consider include the nature of the piping system, ground movement, and other ground stresses. The nature of the piping system. The first consideration is the design of the piping system itself. In a pressurized buried pipeline, such as a water main or wastewater force main, axial thrust forces act on the pipe based on changes in fluid velocity, pipe size, or pipeline direction. This generally happens at fittings such as plugs, caps, valves, tees, bends or reducers. Such hot spots definitely need to be restrained. Ground movement. Earthquakes and ground movement can cause connection failure, beam or shear breaks, and cracks along the length of a pipe. A region's geographic phenomena can greatly determine how much the ground moves. Some regions regularly experience ground movement, whereas others are relatively stable. With its location on the San Andreas Fault, California experiences dramatic earthquakes, causing the ground to move suddenly and with great force. It's no surprise that a high level of restraint is used on water and sewer pipes in many areas along the West Coast. Although other parts of the country located on major fault lines can incur less dramatic ground movement, such movement can still stress water and wastewater pipelines. The New Madrid fault line is particularly noteworthy, as it can affect more than 15 million people in Alabama, Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee. The Ramapo Fault runs about 70 miles through New Jersey, New York and Pennsylvania. Ground movement caused by this fault has stressed piping systems even without full-blown earthquakes. In addition, scientists have warned of earthquake risk from hydraulic fracturing operations. Ground movement can also be caused by seasonal weather changes, especially during winter and spring. The ground freezes in the winter, and ice

Table of Contents for the Digital Edition of Streamline - Summer 2016

From the President: Life’s a Dance
From the Executive Director: Drum Roll Please...
VRWA’s 2016 Conference Highlights
VRWA Says “Until We Meet Again
System Efficiency and Production: Time for a Change???
Confessions of the Chronically Late
OSHA’S Recordkeeping Rule
Revenue and Reasonable Rates
When and How to Use Piping Restraints
Retaining Operators: Is it Really Just About $$?
NRWA Recap
What is WaterPAC?
Note from Myrica Keiser, Executive Director, VRWA
Throwing My Loop: The Secret to Creativity
VRWA Members Corner
eLearning Benefits
Membership Application
Benefits for VRWA Members
Mail Bag
Board of Directors
VRWA Committees
Index to Advertisers/

Streamline - Summer 2016