September 2014

Welcome to ‘Stainless Solutions’ from IMOA. Each month, we will cover a different stainless steel issue with tips on design and specification, and links to technical resources. This month we are highlighting new developments and resources for stainless steel structural design.
New Developments - Stainless Steel Structural Design

Stainless steel is not a new structural material. Industrial and infrastructure applications were developed shortly after the invention of stainless steel about 100 years ago. It is generally used in harsh industrial environments and where protective coatings or corrosion could cause contamination.  The most commonly used sizes are stocked.

The first design research was undertaken when structural welded stainless steel plate was included in the design of St. Louis, Missouri’s Gateway Arch. That led to the world’s first specification for structural stainless steel, which is now known as SEI/ASCE 8.  It covers austenitic and ferritic cold-formed structural stainless steel sections. Subsequent research has included heavier hot-rolled and welded structural stainless steel.  EuroCode 3 has included all common structural shapes for some time.  

While industrial applications still predominate, structural stainless steel has been used for many other memorials and sculptures since the construction of the Gateway Arch in Missouri, such as the US Air Force Memorial and several 9/11 Memorials. It is also increasingly used for security barriers like bollards and gates; pedestrian bridges; building cleaning system rails; structural glass supports for canopies; low profile glass curtain wall supports; and seismic applications.

Despite a significant amount of global research on heavier structural stainless steel sections, there was no North American equivalent to the EuroCode 3 until last year. IMOA made the industry aware of this need and helped to sponsor the effort. The American Institute of Steel Construction (AISC) Steel Design Guide 27: Structural Stainless Steel was published in September 2013. It includes hot-rolled and welded austenitic (304/304L and 316/316L), duplex (UNS S32101, 2304, and 2205) and precipitation hardened (17-4 PH) stainless steel (from 0.125 inches or 3 mm thickness on up), as well as tension bars and bolts.  An AISC webinar on DG 27 is now available on the AISC website.

DG 27 was modeled after AISC 360 and EuroCode 3’s stainless steel section. It covers the most common shapes and design scenarios including fire. DG 27 uses the same equations as AISC 360, modified where necessary with different multipliers. DG 27 also includes guidance on selection and specification of stainless steel including connections.

All structural stainless steel welding should be done in accordance with AWS D1.6.  Stainless steel structural shapes are stocked in Types 304/304L and 316/316L and other alloys are available as custom orders. Below are links to structural design resources, comprising a full list of ASTM and EN product standards, suppliers, research papers, and links to the structural design documents.

Structural Design Resources:

In 1992, six sets of angled, mirror polished arches were installed to span Post Oak Road in Houston. Each curved hollow arch weighs over 2 tons and is made from 0.375 inch (9.5 mm) thick welded Type 316 stainless steel plate, polished to a seamless mirror finish. The arches span 165 ft (50 m) and each is 2 feet (0.6 m) in diameter.  There are also 200 light fixtures built entirely of mirror polished structural Type 316 stainless steel. Both remain spectacular after over 20 years. (Photo credit:  TMR Consulting)

Continuing Education – American Institute of Architects (AIA)

IMOA is an AIA continuing education system approved provider with eight 1-hour programs that are registered for either live face-to-face or distance learning credit.

1. Stainless Steel Sustainable Design
2. Bioclimatic Design With Stainless Steel Weather Screens
3. Stainless Steel Structural Design
4. Stainless Steel Specification For Corrosive Applications
5. Deicing Salt: Stainless Steel Selection to Avoid Corrosion
6. Stainless Steel Finish Specification
7. Advanced Stainless Steel Specification and Problem Avoidance
8. Specification of Stainless Steel Finishes and Grades For Corrosive Applications

Live in-house workshops are also being scheduled for Chicago, November  3 - 6, 2014.

For more information or to schedule a workshop contact Catherine Houska, 412-369-0377 or email

What is IMOA?

IMOA (International Molybdenum Association) is a non-profit industry association, which provides technical information to assist with successful specification of molybdenum-containing materials. Molybdenum is an element. When it is added to stainless steel, molybdenum increases its resistance to corrosion caused by deicing salts, coastal atmosphere and pollution.

If you have a topic suggestion for a future issue of Stainless Solutions or need additional technical advice on stainless steel specification and selection, please get in touch here.

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