An installation for coating a longitudinally-running, strip-shaped metal product includes a tank containing a coating in liquid form, into which the metal product is dipped, a wiping system disposed at a vertical outlet of the product from the tank and intended to wipe each face of the strip-shaped product, at least one ancillary device disposed at an outlet of the product from the wiping system in a manner facing one of the faces of the product, and a holding device holding the wiping system and the ancillary device. The holding device includes a securing unit forming a common lateral support for the wiping system and each ancillary device by using multiple securing points.

A hot-dipped galvanized steel sheet of the present invention includes: a base steel sheet; a ZnMgAl based plating layer provided on at least one surface of the base steel sheet and including, in wt %, with respect to components other than iron (Fe) diffused from the base steel sheet, 5.1 to 25% of Al and 4.0-10% of Mg, and the remainder of Zn and other inevitable impurities; and an interfacial alloy layer having a FeAlZn composition formed between the base steel sheet and the plating layer, wherein the interfacial alloy layer has a thickness of 0.5-2 m and has a dendritic form, the ZnMgAl based plating layer has a ZnAlMgZn.sub.2 ternary eutectic structure, a ZnMgZn.sub.2 binary eutectic structure, and a structure including one or more of an Al single-phase structure having solid-solubilized Zn and a Zn single-phase structure, and agglomerated Al is included in a MgZn.sub.2 structure.