Mandatory: welds on food and pharmaceutical equipment, in seawater and chemical environments, and where hygiene or corrosion-resistance acceptance requirements apply.

Can be simplified: indoor decorative parts, non-corrosive media, and workpieces that will undergo subsequent overall surface treatment (such as overall pickling or electropolishing).

Alternative solution: local mechanical grinding of the weld plus electropolishing can reduce acid use; however, grinding must thoroughly remove the oxidation tint in the heat-affected zone, otherwise the passive film cannot be restored.

Note: waste acid treatment must comply with local environmental requirements and must not be discharged directly.