Method for providing cathodic protection of underground structures
AssigneeInterprovincial Corrosion Control Company Limited
InventorGordon I. Russell
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Abstract
A method and composition for providing cathodic protection to underground steel structures is disclosed in which a composition comprising calcium hydroxide, calcium silicate and calcium nitrite is added to backfill for raising the backfill pH above 8 and an electrical current is applied to polarize the surface of the steel structure whereby the surface of the steel structure is maintained negative relative to the backfill. Magnesium hydroxide and aluminum hydroxide can be used as a substitute for at least a portion of the calcium hydroxide.
Claims15
A composition for providing cathodic protection to underground steel structures comprising about 75 to 90% by weight calcium hydroxide, about 3 to 20% by weight calcium silicate, and an effective amount of calcium nitrite for removal of oxygen.
A method of providing cathodic protection to an underground steel structure comprising adding to a backfill burying said structure an electrically conductive composition containing an effective amount of calcium hydroxide for raising the pH of the backfill to above 8 and precipitating a calcareous film on the structure, an effective amount of calcium silicate for adhering said film to the structure, and an effective amount of calcium nitrite for removing oxygen from said film.
A composition for providing cathodic protection to underground steel structures comprising about 37.5 to 90% by weight calcium hydroxide, about 3 to 20% by weight calcium silicate, at least one of magnesium hydroxide or aluminum hydroxide present in an amount of up to 45%, and an effective amount of calcium nitrite for removal of oxygen.
Dependencies are inferred from the claim text.