Designed for Efficiency and Flexibility
Designed to Specific Project Requirements
CCP is designed to resist internal hydrostatic pressure by a combination of the steel cylinder and helically wound bar. The cylinder thickness, bar diameter, and spacing components can be varied to provide the amount of steel needed for pipeline operating conditions. This flexibility in design can result in substantial cost savings.
With its heavy cylinder and significant beam strength, CCP can be produced in lengths up to 50 feet. Teamed with the self-centering standard joint, CCP has high installation speeds.
Typical CCP joints do not require welded-on joint rings, which reduces both field time and costs. The standard rolled-groove joint utilizes “push-on” technology, which has been in service for over 60 years. Restrained joints utilize a bell & spigot lap joint that is field-welded from the inside or the outside. The restrained joint has a constant cylinder thickness throughout, allowing for full transmission thrust through the joint.
Unlike traditional bar-wrapped pipe, cylinder thickness is not increased in restrained areas. Interior joint gaps are pointed with cement mortar, and exterior joints offer a high level of external corrosion protection by using traditional concrete grout “diapers.” In some applications, such as field testing, subaqueous installations, or in high fill areas with potential long-term settlement, a double gasket joint may be used.
Impact and Vacuum Resistant
After the lining is cured, the steel cylinder is helically wrapped with a continuous mild steel bar applied at a tensile stress of 8,000 to 10,000 psi. The bar wrapping provides the balance of steel required to resist tensile hoop forces. The bar wrapping reinforces the mortar coating and locks it tightly against the steel cylinder creating a composite structure. This composite construction greatly increases the pipe’s rigidity, beam strength, and resistance to impact and vacuum.
In-Service Field Pressure Tapping
A full range of outlets can be economically installed to any diameter of in-service pipe using commercially available equipment and procedures.
The average circumferential stress in the steel cylinder and bar reinforcement of the pipe at design pressure is limited to 36,000 psi, the specified minimum yield strength of the steel used in the cylinder. The actual yield strength of the steel used to manufacture the cylinders is typically greater than 36,000 psi, resulting in an actual safety factor greater than 2 to 1 in the equation.
The required circumferential steel area for a given diameter and pressure class of pipe can be provided by several combinations of steel cylinder thicknesses, and bar diameters and spacing.
Standard designs for CCP are based on a safety factor of 2.0 and a minimum yield of 36,000 psi for the steel and are available through your sales associate. The standard designs provide an allowance for transient pressure 1.5 times the design pressure in the pipe.
External loads of buried CCP pipelines are resisted by the ring flexural strength of the pipe (stiffness) and by the passive lateral earth pressure on the sides of the pipe. The composite wall construction contributes significantly to its rigidity and external load carrying capacity. Our engineers can help determine your project’s specific pipe design based on pressure and earth cover load as well as recommended bedding and back filling procedures.
Special Pipe and Fittings
Northwest Pipe can fabricate virtually any shape or size of specialty pipe or fittings conforming to the applicable sections of AWWA Standards C303 and C208. Flanges to operating pressure of 300 psi conform to AWWA Standard C207. Flanges at greater operating pressure conform to ANSI Standard B16.5. And all of our in-house technicians are independently certified by NACE, AWS and SSPC.
Special pipe includes short lengths, beveled ends, manholes outlets, air valves, blowoffs, and other connections. Fittings include elbows, reducers, and connections to mainline valves and appurtenances. These are fabricated from steel plate or sheet and cement mortar, lined and coated. Fittings include elbows, reducers, and connections to mainline valves and appurtenances. These are fabricated from steel plate or sheet and cement mortar, lined and coated.
Every pipe piece is numbered and delivered in proper sequence for quick installation in the pipeline.
Northwest Pipe Engineering Services
Let Northwest Pipe assist your underground construction project with its engineering requirements. Our professional staff members can
- the design of new products for specialty applications
- shop drawings
- engineering submittals
- coordinating outside sources for specialty fabrications
- non-destructive testing
- product recommendations
- coating and lining recommendations
For more information on our engineering services, please contact us directly: