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Is there a COSHH (Control of Substances Hazardous to Health) information data sheet generally available for stainless steels to outline any risks associated with its handling, fabrication and use.
Acetic acid is a weak reducing acid. It is used in plastics manufacture and is a constituent of foods as vinegar. Ferritic stainless steels such as the 430 type can be considered but normally the 304 types are used for most applications, including handling and storage. Acetic anhydride (CH3CO)2O can be aggressive to either 304 or 316 types in the absence of any water and in the presence of chlorides. Peracetic acid CH3C(O)OOH (peroxyacetic acid) should be safe with stainless steels. Vinyl acetate C4H6O2 may be considered with the 316 types for ambient temperature storage applications.
The austenitic stainless steels are impact tough at ‘cryogenic’ temperatures compared to carbon steels and so are suitable for handling and storage of liquid ammonia at temperatures around -40 degC. The general corrosion resistance of the 304 types should be adequate for installations at most sites, but for coastal or marine sites 316 types should be considered if the outer-casings or parts are exposed.
Dry chlorine gas should not attack stainless steels. Damp gas or chlorine dissolved in water can be a corrosion hazard. Corrosion can take the form of localised crevice and pitting corrosion. Stress corrosion cracking (SCC) can be an additional hazard in damp chlorine gas, if the temperature is high enough.
Citric acid is a weak organic acid, found in fruits such as lemons (citrus) Either the 304 or 316 stainless steel types can be considered for most storage and handling applications. Citric acid is also be used for cleaning and passivating stainless steels.
Hydrochloric acid lacks the oxidising properties that stainless steels need to maintain their ‘passive’ corrosion resistant surface layer. Stainless steel have limited resistance. Building mortar cleaners that contain hydrochloric acid can result in staining and pitting to nearby stainless steel items.
Hydrofluoric acid is extremely aggressive. It is used, along with nitric acid, in stainless steel pickling solution and paste preparations. The 304 and 316 types should be considered non-resistant. Higher grades of stainless steel can have limited resistance.
Nitric acid is strongly oxidising and promotes the resistance of stainless steel to corrosion. Generally stainless steels are resistant to corrosion in nitric acid. Nitric acid is used in the chemical ‘passivation’ of stainless steels. The 304 types are preferable to 316 types. Localised attack at grain boundaries can occur in hot concentrated nitric acid.
Phosphoric (orthophosphoric acid) is a weak acid. Austenitic stainless steels have good corrosion resistance to chemically pure phosphoric acid. Wet process phosphoric acid (WPA) can be aggressive.
Sodium Hydroxide (Caustic Soda) is a strong base, used widely for cleaning metals. Stainless steels types 304 and 316 can be considered resistant below 80 degC, up to the limit of solubility. There can be a risk of stress corrosion cracking (SCC) attack at higher temperatures.