Metal Processing Solutions: Pickling Steel

When we think of the word “pickling”, our minds are likely to shoot off to Grandma’s pantry with her bizarre collection of delicious foodstuff floating in a briny sea. However, when we talk about pickling steel, the result is far less tasty but just as clever.

What is steel pickling?

Those of us who work with metal – particularly with stainless steel – are all too familiar with its fussy temperament. One of steel’s pet hates is the presence of impurities during processing. These impurities may come from welding or heat treatments which leave a residue on the steel, compromising the corrosive resistance of the metal. While mechanical removal of impurities may be a quick and easy option, very often these processes leave abrasive or other tiny particles embedded into the piece.

Steel pickling is a job for chemicals; notably nitric (HNO₃) and hydrofluoric (HF) acids. A pickle liquor, as it’s sometimes referred to, can be made up of a variety of solutions depending on the type of metal and the processes which are to follow.

These fierce acids strip away scale, stains, rust and other impurities, removing damaged areas and layers of chromium depleted metal to reveal the fully alloyed stainless steel beneath. Metal processing plants may also make use of pickling pastes which include an acid solution mixed with an inert carrier to treat particular areas, such as welds.

Pickling sludge, the waste produced from spent pickling acids, needs to be carefully disposed of as it is considered hazardous waste. A responsible steel working company will comply with local laws and ensure that the sludge has been neutralised before being transported to landfill sites.

As with all manufacturing processes, there are alternatives to steel pickling which include smooth clean surface (SCS) and eco pickled surface (EPS), abrasive blasting, wire brushing and hydrocleaning. However, steel pickling still maintains its place as a fast and efficient process.

Whatever your metal requirements are, Steelmor has the skills and experience to make it happen. Please contact our friendly team today.