Force Main Guide Discussion of Design

 Increasing the cyclic life of PVC force mains is essential for ensuring an economical and durable design. Various strategies can be employed by engineers in the design process to enhance cyclic life:

  1. Adjust Pressure Class/Pressure Rating: Engineers can opt for a lower Dimension Ratio (DR), which increases the pressure class or pressure rating. Updating maximum and minimum pressure values (Prs(max) and Prs(min)) based on the Joukowsky Equation or transient analysis is crucial in this approach.
  2. Optimize Pump Cycles: Reducing the number of pump cycles in lift-station or wet-well design contributes to extending the cyclic life of PVC force mains.
  3. Implement Surge-Control Equipment: Minimizing surge-pressure amplitude can be achieved by introducing surge-control equipment. Detailed information on surge-control techniques is available for a more comprehensive understanding.

If thicker-walled pipes, such as DR 21, 18, 14, are utilized, the resulting cyclic life may be overly conservative, exceeding 200 years. Although a high cyclic-life value indicates longevity, it may be unnecessary and less economical.

There is inherent conservatism in PVC pipe cyclic design assumptions. The Joukowsky Equation and Folkman Equation, while providing conservative results, may underestimate cyclic life compared to transient modeling. To address variations in project design assumptions, engineers may apply an additional factor of safety (e.g., 2.0). This factor ensures that the calculated cyclic life is at least twice the desired design life.

The discussion of a design example illustrates the impact of these considerations, emphasizing the need for a balanced and judicious approach. Surge-control techniques, including the use of variable-speed pumps and proper management of entrapped air, play a vital role in enhancing the overall performance and longevity of PVC force mains.

Engineers should also consider multiple surge events, such as regular pump shut-offs and valve closures, using Miner’s Rule to predict failure based on the number of cycles per year and cycles to failure for each surge event.

In summary, a thoughtful combination of design adjustments, surge-control techniques, and a realistic assessment of cyclic life considerations is essential for achieving an optimal and cost-effective PVC force mains design. Link: https://www.uni-bell.org/Portals/0/ResourceFile/force-main-design-guide-for-pvc-pipe.pdf

Comments

Post a Comment

Popular posts from this blog

PVC Gasketed Pipe and the Role of Insertion Lines

Image
If you’ve ever been involved in a water or sewer project, chances are you’ve worked with PVC gasketed pipe . It’s one of the most common materials used in underground utilities, and for good reason: it’s tough, flexible, and built to last. But here’s something many people don’t realize—the performance of the pipe depends heavily on a small mark called the insertion line . What Makes Gasketed PVC Different? PVC pipe with gasketed joints is designed with two ends: one side is the bell (the socket) and the other is the spigot (the smooth end). Inside the bell is a rubber gasket that seals when the spigot is pushed in. This system has a big advantage over glued pipe: the joints stay flexible. That means the pipe can handle ground shifts, temperature changes, and pressure surges without breaking or leaking. For cities and contractors, that translates to fewer repairs and longer system life. The Purpose of the Insertion Line Take a look at the spigot end of a gasketed PVC pipe and you...
Read more

PVC Pipe: A Safe and Trusted Choice for Public Health

Image
Over Ten Million Quality Control Tests Ensure Safety For more than 70 years, PVC pipe has been one of the most rigorously tested and trusted materials in North America. Every stage of its production, use, and disposal has been evaluated and certified by both government and independent regulatory bodies, ensuring it meets the highest safety and quality standards. PVC pipe complies with all health and safety regulations under the U.S. and Canadian Safe Drinking Water Acts, alongside other international guidelines. Regulatory agencies such as NSF International and the U.S. Environmental Protection Agency (EPA) oversee its use through mandatory testing, reinforcing its reliability for public water systems. Moreover, top health organizations, including the U.S. Food and Drug Administration (FDA) and the Consumer Product Safety Commission, have confirmed that PVC is safe for a wide range of applications. A Clean and Safe Solution for Water Systems PVC is widely approved for use in water dis...
Read more

ISO-Compliant, Peer-Reviewed EPD for PVC Water and Wastewater Piping

Supporting Green Infrastructure and Sustainability Goals The Uni-Bell PVC Pipe Association (PVCPA) has introduced North America’s first industry-wide environmental product declaration (EPD) for PVC water and wastewater piping. Verified by NSF Sustainability, a division of the globally recognized NSF International, this EPD plays a crucial role in helping municipalities and businesses meet their green building and infrastructure goals. Developed in compliance with ISO 14025 international environmental standards, the EPD evaluates the environmental impact of seven different PVC pipe products across their entire life cycle. These include PVC pressure pipes for potable water, reclaimed water, and sewer force main systems, as well as PVC non-pressure pipes used in storm sewer and sanitary sewer systems. NSF Sustainability rigorously reviewed and validated the life cycle assessment (LCA), ensuring that all claims adhere to strict verification standards.Unmatched Longevity and Efficiency in...
Read more