A method of inhibiting sour corrosion of a metal surface including contacting the metal surface and composition in a corrosive medium. The corrosive medium includes hydrogen sulfide. The composition includes an aliphatic alcohol comprising 1 to 6 carbons, a polysorbate, a glycol compound, and a substituted benzimidazole compound. The composition includes a weight ratio of the substituted benzimidazole compound to the polysorbate of 1 to 3.

A method for inhibiting corrosion in a refinery crude distillation unit includes introducing a corrosion inhibition composition to the refinery crude distillation unit. The corrosion inhibition efficiency of the corrosion inhibition composition may be at least 80%. The corrosion inhibition composition may include a carrier fluid and a corrosion inhibitor consisting essentially of a compound represented by Formula (I): ##STR00001## where R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are each, independently, a hydrogen or an alkoxy group, and m and n are each, independently integers ranging from 2 to 10, wherein R.sup.5 and R.sup.6 are each, independently, a saturated C.sub.6-C.sub.10 hydrocarbon group or an unsaturated C.sub.6-C.sub.10 hydrocarbon group.

In one aspect, provided is an etchant composition that is able to reduce etching nonuniformity. An aspect of the present disclosure relates to an etchant composition for etching of a layer to be etched that contains at least one metal. The etchant composition contains an etching inhibitor, an acid including at least a nitric acid, and water and has a pH of 1 or less. The etching inhibitor is at least one nitrogen-containing compound selected from the group consisting of polyalkyleneimine and a polymer having a constitutional unit derived from diallylamine.

A method for inhibiting corrosion in a refinery crude distillation unit includes introducing a corrosion inhibition composition to the refinery crude distillation unit. The corrosion inhibition efficiency of the corrosion inhibition composition may be at least 80%. The corrosion inhibition composition may include a carrier fluid and a corrosion inhibitor consisting essentially of a compound represented by Formula (I):

##STR00001##

where R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are each, independently, a hydrogen or an alkoxy group, and m and n are each, independently integers ranging from 2 to 10, wherein R.sup.5 and R.sup.6 are each, independently, a saturated C.sub.6-C.sub.10 hydrocarbon group or an unsaturated C.sub.6-C.sub.10 hydrocarbon group.