This powerpoint presentation investigates the
mechanism(s) of corrosion on ductile iron
pipe (DIP) with polyethylene encasement
(PE) in accordance with AWWA C105
standard. Methodology included the following:
simulate small gap between DIP and PE
surface 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 trapped
fluid as a function of time. Presentation conclusions indicate that:
asphaltic DIP showed little to no signs of
corrosion,
protective asphaltic coating prevents contact
between corrosive pore fluid and DIP, and
no semi-volatile organics were detected; annealing oxide DIP acts as a
protective layer and
pitting rings at top
caused by greater
dissolved oxygen; bare DIP offered
no protective layer with
pitting near top rings and
uniform corrosion at
lower portion; corrosion mechanism is
strongly influenced by dissolved
oxygen,
PE deprives system of oxygen, and
dissolved oxygen increases corrosion;
pH increases as corrosion proceeds;
LPR readings indicate general corrosion; and,
semi-volatile organics are
not a factor in corrosion control. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 2.4 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 40 |
| Published : | 11/01/2008 |
