Overview of Prestressed Concrete Cylinder Pipe (PCCP)
Prestressed Concrete Cylinder Pipe (PCCP) was first manufactured in 1942 as lined cylinder pipe. This pipe, constructed by welding steel joint rings to a steel cylinder, was then coated internally with concrete. The outer surface was wrapped with high strength steel wire directly over the steel cylinder and covered with a cement-based mortar coating. Diameters ranged from 16 inch to 48 inch, and it was only after the revision of AWWA C301 Standard in 1979 that lined cylinder pipe standards were increased to include 60 inch diameter pipe. The majority of Prestressed Concrete Cylinder Pipe (PCCP) manufactured in the 1940's is equivalent to AWWA C301 Lined Cylinder Pipe.
Embedded Cylinder Pipe (ECP) was introduced in 1952 and has concrete encasing the steel cylinder on both sides. Although it was originally produced in sizes as small as 24 inches, the manufacturing process encountered safety issues in vertical casting of pipe smaller than 48 inch in diameter and therefore, the industry generally restricted itself to 48 inch and larger pipe. During the 1950's, manufacturers also increased the wire strength and stressed the wire up to 75% of the minimum ultimate allowable. Oil tempered wire was also tried but discontinued because of the susceptibility to corrosion.
The introduction of the AWWA C301 standard in 1964 accepted thinner sheet steel for cylinders in all Prestressed Concrete Cylinder Pipe (PCCP), which functions more as a form around which the pipe is constructed. In the 1970's, PCCP became the pipe material of choice because of the large diameters available and that the pipe had had very few failures.
In recent years, a number of significant improvements in the Prestressed Concrete Cylinder Pipe (PCCP) manufacturing process and quality control procedures have been brought about by the American Concrete Pressure Pipe Association (Prosser, 2000) and the industry which it represents through:
- A strong focus on quality control and technology development;
- A water industry landmark compliance audit and certification program;
- Development of rigorous standards;
In 1992, AWWA C301, the manufacturing standard for Prestressed Concrete Cylinder Pipe (PCCP), was completely revised to incorporate new and more detailed testing of virtually every aspect of the pipe manufacturing process, including controls on wire, mortar coating mixing, application, performance, and testing. The result is that PCCP designed and manufactured today is much better than the PCCP manufactured at any time over its previous 50-year history.
It is reported by the American Concrete Pressure Pipe Association (ACPPA) that 90 out of the 100 largest water utilities in the United States use Prestressed Concrete Cylinder Pipe (PCCP) in their water systems and the demand for PCCP is steadily increasing for transmission pipelines. Furthermore, PCCP has the lowest water main break rate per 100km than any other pipe material (Prosser, 1996).