SPIRAL RIB PIPE (SRP)

is one of many innovative pipe products developed by Pacific Corrugated Pipe Company during its long history in the drainage industry. This efficient product was developed in response to the needs of drainage designers for a pipe product with the hydraulics of smooth wall pipe plus the many other advantages of corrugated metal pipe.

Pacific Corrugated Pipe Company has developed a variety of rib profiles to provide the widest range of sizes available in the industry. SRP is available in sizes of 18 inches through 144 inches in steel and 18 inches through 96 inches in aluminum alloy.

Fabrication: SRP is a flexible metal conduit manufactured from a continuous strip of galvanized steel, aluminized Type II steel, or aluminum alloy. Available steel thicknesses are .064 inch, .079 inch, and .109 inch. Available aluminum thicknesses are .060 inch, .075 inch, and .105 inch. The coil strip is passed through a forming line which forms the ribs and prepares the edges. The formed section is then helically wound into pipe and the edges are joined by mechanical lockseaming.

Hydraulics: In 1983, a series of friction factor tests were conducted on SRP at the Utah Water Research Laboratory located at Utah State University in Logan, Utah (Hydraulics Program Report No. 83). Tests were conducted on 24-inch and 36-inch SRP with open ribs and 36-inch SRP with ribs filled. Comparison of the results with ribs filled to open ribs showed little influence on flow due to the open rib section.

Analysis of the test results and theoretical scaling to larger sizes resulted in a recommended value of n = 0.011 for use in Manning’s Formula for all diameters.