February 2015

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 discussing the role of stainless steel as a structural material in restoration projects.
Structural Restoration With Stainless Steel

Stainless steel is commonly used for the restoration and renovation of buildings and structures. IMOA has added a new webpage providing information on the role that structural stainless steel applications play in restoration projects. This issue highlights some of the topics covered.

Molybdenum-containing stainless steels are the obvious choice for longevity in more corrosive environments such as those exposed to acid rain, industrial pollution, chlorides (coastal or deicing salt), volcanic gases, soil and rock. Molybdenum Preserving Venice provides an overview of how one city is using Type 316 and 2205 stainless steel for a wide range of preservation applications, particularly stone and masonry reinforcement.

Ground and Rock Anchors

The stability of a hillside or seawall can be critical in preventing damage to a site or building. The chemistry of the soil or rock and the water moving through can make this a very corrosive service environment. The article Reinforcing cliffs and walls describes reconstruction of a crucial seawall in England and stabilization of a rock face at the Acropolis World Heritage Site.

Concrete Reinforcement

Stainless steel reinforcing bar, welded wire mesh and cable for pre- and post-tensioning of concrete should all be considered for new concrete installations, replacement, and repair in chloride (coastal or deicing salt) exposure applications. Read Duplex rebar restores resistance to waves to learn how the Hassan II Mosque in Morocco, one of the largest in the world, was saved using 2205 rebar when carbon steel failed.

Larger Structural Sections - Statue of Liberty Restoration

Since its installation in New York in 1886, the Statue of Liberty has become one of the most well known sculptures in the world.  Galvanic corrosion caused structural deterioration making a significant restoration necessary in 1986.

The original structure of the 46-meter (151-foot) statue had a framework of puddled iron consisting of three distinct components – a central support pylon, secondary support framing that extended outward from the pylon and armature bars in direct contact with the copper skin. Severe corrosion of the iron armature, and to a lesser extent the secondary supports, had occurred by 1981. The armature expansion due to corrosion was causing degradation of the copper exterior.

Photo: Rudy Norff

Molybdenum-containing Type 316L stainless steel was chosen to replace the entire iron armature of the statue except for a few bars in the right sole of the foot. The secondary iron framework that had originally supported the armature was replaced with high strength, highly corrosion resistant molybdenum-containing duplex stainless steel (UNS S32550). The original pylon was retained. Type 316 stainless steel was also used to replace the circular stair treads, the emergency elevator, and for a redesigned pedestal stairway.  More project details are available on the IMOA website.

Photo: Christopher J Fraser

Stainless Solutions e-newsletter archive

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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 both live face-to-face and 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

For more information or to schedule a workshop contact Catherine Houska, 412-369-0377 or email chouska@tmr-inc.com.

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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In providing consultation or other assistance with respect to technical issues, any consultation, assistance or material is provided for the general information of the recipient and should not be used or relied upon for any specific application without first securing competent advice. IMOA and their respective employees, consultants and members (i) make no representation or warranty, express or implied, of any kind with regard to such consultation, assistance or material including no representation or warranty of  suitability for any general or specific use; (ii) assume no liability or responsibility of any kind in connection  therewith; and (iii) disclaim any and all liability for any claim that arises therefrom. 

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