Heather Allain, Executive Director, Materials Technology Institute (MTI), tells us about her passion for materials and the importance of MTI’s work to provide awareness of safe, reliable and sustainable materials use.
Materials selection for any piece of equipment or a process system is rarely a simple task, unless you are exactly replicating something successful. Often engineers will have a checklist to help them narrow down the choices, eliminating groups of materials that are not suitable for various reasons. Austenitic 300 series stainless steels containing 7-35% nickel will have most if not all of the boxes checked for being suitable where a stainless steel is desired.
The sudden failure of a building or bridge is mercifully a rare event, thanks largely to international or national standards: structures are designed in accordance with a design standard, using products conforming to a product standard and manufactured using techniques and to a quality level defined in a construction standard.
Each family of stainless steels has its strengths and weaknesses. Ferritic stainless steels have useful properties – a lower rate of thermal expansion, higher thermal conductivity, strong ferromagnetism and very high resistance to chloride stress corrosion cracking (SCC). When looking at selecting any alloys, it is important to consider all the factors for successful usage.
Awareness about robustness and durability of bridge design has grown since Morandi’s time. The new San Giorgio Bridge (its successor) in Genoa was designed by Renzo Piano and inaugurated in 2020.
The duplex alloys are “problem-solving alloys” for good reason, they have been successfully used in many places where carbon steels and standard austenitic alloys have failed. Just like with the austenitic family, there are many different duplex alloys to choose from, with corrosion resistance varying from moderate with the lean duplex alloys to very high with the superduplex alloys.
The selection of an alloy should be guided by careful examination of the needs of the application. Before making a switch, it’s important to fully investigate an alloy’s strengths, weaknesses and applicability to your structure.
While it may require an initial higher investment when compared with other materials, stainless steel’s unique properties deliver long-term performance and economic benefits including minimum downtime, reduced maintenance costs and reduced environmental impacts.
Even small quantities of nickel in an application can make a big difference to successful deployment.
The upstream and midstream oil and gas industries rely on nickel-containing corrosion resistant alloys for flowlines and risers. Rodrigo Signorelli, Outokumpu’s lead technical manager for marine and energy, explains how alloys reach the market.
Partially corrugated stainless steel service pipes have reduced water leakage rates drastically in Tokyo where they were introduced in the 1980s. Now other innovative water authorities faced with the urgent need to reduce water loss are also examining the nickel-containing stainless steel solution.