AWWA ACE68558

This powerpoint presentation investigates themechanism(s) of corrosion on ductile ironpipe (DIP) with polyethylene encasement(PE) in accordance with AWWA C105standard. Methodology included the following:simulate small gap between DIP and PEsurface and where moisture is trapped;PE test of 3 DIP conditions;annealing oxide coating;removed annealing oxide coating (Bare);asphaltic coating (as manufactured); and,sample and chemically analyze trappedfluid as a function of time. Presentation conclusions indicate that: asphaltic DIP showed little to no signs ofcorrosion, protective asphaltic coating prevents contactbetween corrosive pore fluid and DIP, andno semi-volatile organics were detected; annealing oxide DIP acts as a protective layer andpitting rings at topcaused by greaterdissolved oxygen; bare DIP offeredno protective layer withpitting near top rings anduniform corrosion atlower portion; corrosion mechanism isstrongly influenced by dissolvedoxygen, PE deprives system of oxygen, and dissolved oxygen increases corrosion;pH increases as corrosion proceeds;LPR readings indicate general corrosion; and,semi-volatile organics arenot a factor in corrosion control. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2008

Number of Pages:

40

File Size:

1 file , 2.4 MB