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Here's the "inside story" on how Price Brothers quality and reliability is built into every step!
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In our cylinder shop, an automatic helical welding machine forms and welds continuous steel cylinders to the right diameter and then cuts them to the proper length. In some cases, cylinders are formed from longitudinally welded steel sheets. Each batch of coil or sheet steel used for our cylinders must first pass our own quality assurance laboratory's tests for mechanical characteristics as required by AWWA C-301.
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Before and after the bell and spigot joint rings are welded to the cylinder, they are checked for roundness and to be certain their zinc metallized coating is of the proper thickness. Then each cylinder is mounted on our hydrostatic tester, filled with water, and pressurized to stress the steel between 20,000 and 25,000 psi -- far more stress than the cylinder will be required to endure in actual service. During this test the cylinder's entire outer surface and all weld joints are carefully inspected for watertightness. Since the cylinder serves as an impermeable membrane within the pressure pipe, this hydrostatic test is necessary to be sure the cylinder is water tight.
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As the cylinder assembly spins rapidly, high-strength concrete is centrifugally cast onto its inner wall. This concrete core gives the pipe its structural strength to withstand heavy external loads. The spinning action helps the concrete form a dense and uniform core which is finished to give the pipe its very smooth inside surface. At the time the core is cast, we also take several test samples from the concrete batch which we cure along with the pipe for later compression load testing in our lab. These test samples must meet compression requirements before the pipe can proceed to prestressing.
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After the core is cured, the pipe is helically wrapped with steel prestressing wire while the pipe exterior is being coated with a cement-rich slurry. This prestressing gives the pipe strength to accommodate high internal water pressure and external loads. By varying the spacing between the individual wraps around the pipe, we determine the amount of compression placed upon the steel cylinder and concrete core. Samples of all the wire we use must pass tests for ductility, tensile strength, and other physical characteristics. As the wire is wrapped, we carefully monitor and record the tension load and continuously check the wire spacing. Steel anchor blocks at each end of the pipe permanently hold the wire under the proper tension.
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To complete the production of each length of concrete pressure pipe, the cylinder and prestressing wire are again covered with a cement slurry closely followed by a dense coating of cement-rich mortar. This encases and covers the wire and cylinder to provide protection against corrosion. On large diameter embedded cylinder pipe, the steel cylinder is positioned within the concrete core and the cement-slurry-coated prestressing wire is wrapped around the outer surface of the core. The wire and core are then coated with slurry and mortar for corrosion protection.
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Following the controlled curing of the external mortar coating, the pipe is carefully cleaned for final inspection. Identification codes are then painted on the inside of each pipe's spigot end indicating its pressure class. All pipe produced by Price Brothers is custom built to meet the specifications of your particular project. The pressure pipe we build for you has "your name on it" all the way through production and is ready to meet your every requirement, including prompt delivery.
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The quality and reliability of Price Brothers products must be matched by the quality and reliability of our service -- especially at the time your pressure pipe is shipped to the construction site. Whether it goes by truck, train, or sea-going barge, we make sure your pipe is skillfully loaded, packed, and shipped to minimize any risk of on-site downtime or pipe damage.
Each length of pipe and each fitting arrives at your job site on schedule and according to your laying sequence. In the case of our largest sizes of pipe (diameters from 96 inches up through 192 inches), our own special transporters can be used on site to assure efficient and timely delivery right to the trench.
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Our Price Brothers field service representative is a familiar figure on most pipeline projects. He's there to teach proper installation technique and help spot potential problems. Because of the rigid and rugged design of our pressure pipe, special bedding or backfilling is generally not required. Installation is quick and easy, with a minimum of equipment -- usually the equipment that digs the trench also places the pipe. To guide everyone directly concerned with proper engineering and installation techniques, Price Brothers Company provides contractors and consulting firms with our 60-page Installation Manual for Price Brothers prestressed concrete cylinder pipe.
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