Abstract: The invention relates to 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) positioned on the first layer and capable of plugging the pores of the first layer (11). The first layer comprises substantially pure zinc or an alloy or pseudo-alloy of zinc, the alloy or pseudo-alloy comprising at least 50 wt % zinc, and preferably between 0.5 wt % and 40 wt % aluminum. The second layer comprises a paint with a base of at least one organic resin, the paint being either single-component in an organic solvent or co-solvent, or dual-component. At least one among the first layer and second layer comprises a bactericidal agent. The invention also relates to a corresponding coated piping member and method for depositing the coating.

Abstract: The invention relates to an outer coating (9) for an underground piping element (7) made from iron, in particular cast iron, the outer coating having a first porous layer (11) and a second porous layer (13) positioned on the first layer and able to plug the pores of the first layer, the outer coating being characterized in that: the first layer includes a substantially pure zinc or a zine alloy or pseudo-alloy, the alloy or pseudo-alloy including, in terms of mass, at least 50% zinc, preferably between 0.5% and 40% aluminum, and the second layer comprises a one-component paint in the aqueous phase made from at least one synthetic resin emulsified, dispersed or dissolved in water. The invention also relates to a corresponding coated piping element and method for depositing the coating.

Abstract: A cast iron piping system element has an outer coating comprising a first, inner porous layer consisting of zinc/aluminum alloy containing from 5 to 60% of aluminum, and a second, outer pore occluding layer of an organic or mineral binder in an aqueous, solvent or powder phase with a thickness of 100-140 .mu.m.

Abstract: A cast-iron pipework element adapted to be buried has an external coating made up of an inner layer of zinc, a porous intermediate layer of zinc/aluminium alloy containing from 5 to 55% of aluminium, and a porous outer layer, or pore-blocking layer, comprising an organic binder, especially a water-based paint, a bitumen varnish or an epoxy resin.

Abstract: A multilayer pipe surface coating for water system elements requiring high corrosion resistance includes at least one conversion layer and one thermosetting synthetic resin layer.