Credit: Photo: CONTECH Construction Products Inc.
Depending on the application and material, pipes can be a few inches in diameter, or big enough to drive a truck through. The flexibility and lightweight of corrugated PVC pipe contributes to its ease of handling.
Credit: Photo: American Cast Iron Pipe Co.
Ductile iron pipe is commonly specified for water and wastewater applications, as in this installation of 42-inch-diameter pipe.
Living By the Code
Most major utilities are guided by local codes and specifications that require them to choose a specific type or size of pipe for the application. While it may be convenient to have some of the decision already made, sometimes the limitation can be challenging.
“We have construction specifications that dictate type required,” said Chris Holmes, PE., senior engineer with Dayton, Ohio's public works department. “The complete specifications were last reviewed in 1990, and we are now in the process of a rewrite. Minor revisions occur as needed.”
Holmes said crews in his area have installed more than 50,000 linear feet of ductile iron pipe in the past five years, mostly in new construction, but also on miscellaneous replacement projects.
Larry Modlin, director of public works for Boiling Spring Lakes, N.C., said that the installation costs associated with concrete pipe put the material out of his budgetary range. “We use HDPE—NCDOT approved—with couplers in most cases,” he said. “We use some tar-coated, galvanized, corrugated metal on larger-diameter installations due to cost, and the contact with water that is heavy with tannic acids from the pines.” Modlin added that his agency also installs driveway culverts, which usually are galvanized, corrugated steel.
Linings are also an option to consider. If corrosion or abrasion is a concern, as might be the case with wastewater or sewage, one type of pipe might be specified, along with a liner that protects the pipe itself from damage. Naturally, specifying a liner will add to the upfront cost of an installation, but it can extend the life of a pipe, leading to long-term cost savings. Abresist Corp., an Urbana, Ind.-based manufacturer, is just one of the companies that offers such products. Their liners—fused cast basalt and ceramic products—increase a pipe's resistance to corrosive fluids and abrasive slurries.Natural Resources
The pipe industry is supported by a number of associations representing the different types of pipe from which a professional can choose. Most of these associations' members are manufacturers, joined together in the common goal of promoting their type of pipe over others. While each group understandably has a vested interested in its own type of pipe, each offers a wealth of resources for pipe specifiers to rely on when making a balanced, well-informed decision.
For example, the American Concrete Pipe Association (ACPA), like many other groups, runs a Web site containing resources and technical data, including design and specification guidance. The ACPA offers a number of “Buried Facts,” downloadable documents on topics such as culvert inspection, material durability, and least-cost analysis of bids. Most pipe association Web sites, such as the Plastics Pipe Institute site, discuss the use of pipe in different installations.Future Trends
As public works dollars become increasingly scarce, manufacturers and pipe specifiers alike are working toward finding solutions that enable pipe users to get the most bang for the least number of bucks.
“In the past several years, we have seen a real shift in the industry, as far as owners and engineers accounting for the benefits of a particular product,” said Kimberly Paggioli, P.E., marketing manager for Houston-based HOBAS Pipe USA. “The emphasis is on total life cycle cost, and less on, ‘How cheaply can we get this project built?' With less money going toward infrastructure, and more need as the systems age, agencies are having to make sound investment decisions for the future.”For more information, visit the following organizations:
American Concrete Pipe Association
American Concrete Pressure Pipe Association
Cast Iron Soil Pipe Institute
Ductile Iron Pipe Research Association
National Clay Pipe Institute
National Corrugated Steel Pipe Association
Plastics Pipe Institute