What is Pickling

Stainless steel pickling involves the use of chemical treatment, generally strong, corrosive acids, to eradicate metallic contamination, heat treatment scales, and welding scales from the surface of stainless steel components. The process aims to strip away a thin layer of metal from the exterior of the stainless steel part, which is distinctly different from the descaling process that eliminates visibly thick oxide scale.

Pickling plays an integral role in preparing stainless steel for optimum corrosion resistance. The process primarily addresses surface defects resulting from manufacturing and production processes. Such impairments could range from scale layers formed during heat treatment, annealing colors from grinding or welding, deposited metal oxides or extraneous rust, iron abrasion from processing with steel tools, to the formation of chromium carbide when drilling without cooling lubricants or forming martensite during cold forming.

Why is Pickling Necessary for Stainless Steel?

Stainless steel is known for its exceptional corrosion resistance, but it is not entirely immune to the effects of oxidation and other surface contaminants. Over time, stainless steel can develop scale, rust, or other impurities that not only compromise its appearance but also diminish its performance. This is where pickling comes in.

The primary purpose of stainless steel pickling is to remove these unwanted surface contaminants and restore the material to its original condition. By eliminating impurities, pickling ensures that the stainless steel retains its exceptional corrosion resistance and mechanical properties for extended periods, making it more durable in aggressive environments.

The pickling process for stainless steel involves the use of an acid solution that dissolves the scale, rust, or other imperfections, leaving behind a clean and smooth surface. This acid solution is typically a mixture of nitric and hydrofluoric acid, although variations of pickling solutions exist depending on the specific requirements of the stainless steel product.

What Our Customers Are Saying

“Allegheny Surface Technology has performed several services throughout the years for us and played a crucial role in getting a critical fill line up and running over the last year. On short notice last June, they were able to mechanical and electropolish several of our critical parts and get them back to the site to meet our aggressive timeline. Allegheny Surface has also come on-site to perform various services such as mechanical and electropolishing of different equipment. Their technicians were efficient and made safety a priority.”
- Jeremy- Technical Manager - AstraZeneca, OH
"We have been working with Allegheny Surface Technology for almost ten years. Our company supplies the pharmaceutical, semiconductor, and fine chemical markets with specialty stainless steel shipping containers for transporting, storing and processing sensitive liquids used in their processes. We needed to partner with a reputable and reliable metal finishing company which would meet our material specifications, make consistent deliveries, all the while communicating results on a timely basis; this is why we choose Allegheny Surface Technology, and continue to grow our business, together."
- Tom Leftwich at Black Forest Container Systems, LLC
“Allegheny Surface Technology visited the fabrication shop to discuss the best plan to pickle passivate a large quantity of spools ranging from 4” to 36” stainless piping for a waste water treatment facility. Sally’s communication and tracking was great throughout the multiple batches we sent, and we consistently received great quality with a quick turnaround.”
- Melanie - Shop Foreman at G.M. McCrossin
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