Outer coating for an underground piping member made from iron, coated piping member and method for depositing the coating

摘要

An outer coating (9) for an underground piping member (7) made from iron, in particular cast iron, the outer coating comprising a first porous layer (11) and a second porous layer (13) disposed on the first layer and capable of plugging the pores of the first layer, the outer coating being characterised in that: the first layer comprises substantially pure zinc or an alloy or pseudo-alloy of zinc, the alloy or pseudo-alloy comprising, in terms of mass, at least 50% zinc, and preferably between 0.5% and 40% aluminium, and the second layer comprises a one-component paint in the aqueous phase made from at least one synthetic resin emulsion, dispersed or dissolved in water. A corresponding coated piping member and method for depositing the coating.