This part of ISO 27831 specifies processes for the cleaning of the surfaces of ferrous metals and their alloys to remove any irrelevant or unwanted deposits or other material at any stage of manufacture, storage or service and for the preparation of these surfaces for further treatment. It does not cover cleaning operations associated with the preliminary removal of heavy deposits of oil, grease or dirt accumulated during operational service, preparations for welding or the cleaning of electrical contacts. However, many of the processes included in this part of ISO 27831 may be used for these operations at the discretion of the users of this part of ISO 27831. This part of ISO 27831 covers processes which are needed for the preparation of metal surfaces prior to the application of the following surface coatings: — electrodeposited metal coatings; — autocatalytic metal coatings (autocatalytic and displacement types); — conversion coatings; — hot-dipped coatings; — sprayed metal coatings; — diffusion coatings; — coatings produced by vitreous enamelling; — coatings produced by physical vapour deposition of aluminium and cadmium; — powder coatings. This part of ISO 27831 describes processes for carrying out the following treatments: — degreasing; — descaling; — pickling; — de-rusting; — chemical smoothing; — electropolishing. This part of ISO 27831 relates the processes described above to the following metals: — non-corrosion-resisting steels, cast irons and pure irons; — corrosion-resisting and heat-resisting steels.