Abstract
The relationship of laboratory fluid flow corrosion test techniques to flow-accelerated corrosion in field applications and the parameters required to apply laboratory data effectively in the field were studied. Single-phase, aqueous, sweet corrosion of steel in turbulent pipe flow (12.7 mm and 25.4 mm diam) was correlated to corrosion in jet impingement and rotating cylinder tests. All tests were conducted simultaneously, using the same test fluid to minimize environmental variables and to allow a direct, realistic comparison of test methods. Rotating cylinder electrode corrosion rates did not correlate with pipe flow based on wall shear stress or mass transfer for flow-accelerated corrosion of carbon (C) steel in the environment studied. Jet impingement corrosion rates for the test ring at r/r0=3 correlated with pipe flow based on wall shear stress. The general equation for flow-accelerated corrosion of C steel under turbulent flow conditions in this environment was expressed as: Rcorr = a τwb where Rcorr was the C steel corrosion rate in mm/y and τw was the wall shear stress in N/m2. Effects of solution chemistry were contained in the equation coefficient and exponent and require further experimental definition. The physical fluid and hydrodynamic parameters were included in τw. Use of wall shear stress as the correlating factor did not imply a shear mechanism for corrosion acceleration. Wall shear stress was found to be a hydrodynamic factor that can be used effectively to relate fluid flow in different geometries, allowing valid comparison of laboratory tests and field operations.
