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Stainless Steel Applications
Penn Stainless Products, Inc 190 Kelly Road
Quakertown, Pa 18951800-222-6144 Fax: 215-536-3255
www.pennstainless.com & www.dynamicwaterjet.com & www.pipeandtubes.com
Overview
The Costs of Corrosion
Corrosion Happens…..So What!?
Well… things fall apart.
Reducing the Impact of Corrosion
“Approximately one-third of the costs could be reduced by broader application of corrosion resistant materials and the application of best corrosion related practices (Battle Study).”
“Virtually all premature corrosion failures occur for reasons which were already well known and these failures can be prevented (Mars Fontana).”
Progreso Pier Mexico: Applying Better Practices
• The 6,980 foot pier was constructed from 1937 – 1941 using 304 stainless rebar
• In 1998, Ramboll consulting engineers inspected the pier and reported minimal structural fatigue
What is Stainless Steel? What makes it “Stainless”?
• Stainless steel must have at least 10% chromium in its content to be classified as a stainless steel.
• Nickel, Molybdenum and other elements are often combined with chromium to improve the corrosion resistance, strength, or heat resistance of the material.
• There are over 50 different “flavors” of stainless steels that can be selected for different applications and processes.
Let’s take a step back. What Makes Stainless Steel work and how do we make stainless steel work better on our projects?
What Makes Stainless Work?
Chromium Oxide Layer
Oxide Layer Damaged
Chromium Oxide Layer Repaired
For the Chromium oxide to repair—oxygen must be present!
This Chemistry “stuff” matters…a lot!
How to Preserve the Chromium Oxide Layer
Summary of Best Practices for Handling Stainless Materials
1. Keep your stainless and carbon steel fabrication areas separate.
2. Separate stainless and carbon inventories. 3. Use stainless steel processing and handling equipment
when possible.4. Use Work table bearers; non- stainless lifting 'dogs' and
chain marks can introduce iron contamination. Non-metallic contact materials and vacuum lifting equipment should be used.
5. Packing & Shipping – Tarp your stainless steel fabrications.
6. Communicate with your partners about the proper treatment of stainless steel
Now you know what to do. Does everyone else?
Do not allow grinding to take place near stainless fabrication.
NYC Far Rockaway
• Carbon Contamination from grinding
• Deicing salt
Part 2: Types of Corrosion
• Uniform Corrosion: Also known as general corrosion, is characterized by an even, general wasting away of metal from the corroding surface.
Was the correct material selected?
Pitting Corrosion
• Pitting Corrosion: described as an extreme case of localized attack which produces cavities or pits in the material.
• Was the stainless steel maintained correctly?
• Stainless Steels are susceptible to pitting corrosion.
• Avoid Chlorides.
316/L 7” SQ x ½ Wall Structurals, Polished with Minor Pitting Corrosion
Pitting / Surface Corrosion
• Staining from iron contamination
• Salt and chlorides present
Surface after passivation
Crevice Corrosion
• Crevice Corrosion: a particular form of localized corrosion which occurs in crevices formed between two surfaces.
• When possible, avoid tight corners or crevices in design
• Avoid spot welding, use continued welds when possible
• Use non absorbent gaskets, avoid chlorides
It’s All About the Surface Finish
Rougher surface is harder to clean, harder to remove contamination and more prone to corrosion
Accelerated salt spray test
Source: British Stainless Steel Association
Polished 304/L Stainless Steel I Beams (Cornell University)
Dairy Processing Facility: polished surface improves appearance while enhancing corrosion
Deeper Collaborations
• We need deeper, more open collaborations & dialog in order to “discover” and solve problems
• Work closely with suppliers and customers to solve technical challenges, save costs and offer better products and services.
• Our aim is to be this type of collaborative partner.