Corrugated Steel Pipe and Steel Structural Plate

The base metallic coating data provided in this section are limited to the following values for galvanized metals:
  • 6 < pH < 8
  • resistivity ≥ 2,000 ohm-cm
  • soft waters considered hostile when resistivity ≥ 7,500 ohm-cm
For aluminized type 2, the following values apply:
  • 5.0 < pH < 9.0; Resistivity > 1,500 ohm-cm
  • soft waters not considered to be a problem
Estimate the service life for the interior base metallic coating using Equation 14-3
EquationObject336403
Equation 14-3.
The basic interior service life for 18-gage corrugated galvanized metal pipe is provided in the table following Equation 14-4 for pH values of 7.3 and lower and using the equation for pH values in excess of 7.3.
EquationObject337404
Equation 14-4.
where:
  • L
    i
    = interior years
  • R
     = resistivity (ohm-mm)