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Sea‐Water Infiltration: The Dramatic Corrosion of Ductile‐Iron Rising Mains
Author(s) -
LONG M. J.
Publication year - 1994
Publication title -
water and environment journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 37
eISSN - 1747-6593
pISSN - 1747-6585
DOI - 10.1111/j.1747-6593.1994.tb01147.x
Subject(s) - sewerage , infiltration (hvac) , corrosion , sewage , environmental science , hydrogen sulphide , metallurgy , chloride , environmental engineering , materials science , composite material , sulfur
Repeated failures of a ductile‐iron sewage rising main, after only three years’ use, led to an investigation into the cause of the problem. Of particular concern was the fact that a pipe failed at an operating pressure of less than a quarter of its nominal 40‐bar rating after such a short period. Serious internal corrosion, concentrated along the soffit of the rising main, resulted in tensile failure under pressure. An analysis of the sewage revealed high concentrations of chloride and sulphate, resulting from major infiltration of sea water into the sewerage system. The combination of the high concentrations of inorganic sulphates, and the presence of sulphate‐reducing bacteria normally found in domestic sewage, is believed to have resulted in the production of a large concentration of hydrogen sulphide which was then oxidized to sulphuric acid by air entrained at the pumping station.