Metallic corrosion is the result of electrochemical interaction between a metal and substances present within its operating environment (like water). Corrosion results in degradation of material to the point where it is no longer mechanically or structurally fit for its purpose. Corrosion presents a formidable global challenge. It affects many products and almost all infrastructure — through increased maintenance, shorter product lifecycles, end-of-life management and overall utilization of more resources over a product’s lifetime.
The economic and environmental impact is significant, and it is time to place the fight against corrosion in a proper sustainability context.
The International Measures of Prevention, Application and Economics of Corrosion Technology (IMPACT) study by NACE estimates the global cost of corrosion to be $2.5 trillion annually — equivalent to around 3% of global GDP in 2018. However, it also estimates that existing corrosion control practices could save 15% to 35% of the cost of corrosion, equating between $375 and $875 billion globally each year (NACE International, 2016).
Corrosion impacts heavily on the environment
The consequences of corrosion-related impacts on the environment are not included in this study but are increasingly important. In response to greater interest in issues related to environmental impact and sustainability, engineers are encouraged to design products and infrastructure that can minimize negative environmental and societal impact. Sustainability in design, optimizing a product’s lifecycle, minimizing maintenance requirements and end-of-life upcycling/recycling are all becoming an important part of product performance, quality and overall cost.
In the future, there could be more burden placed on product manufacturers and asset infrastructure owners towards end-of-life management, so making early considerations in the design and planning stage will become a more crucial aspect of engineering. Life cycle assessments (LCAs) are becoming more important products from both a customer and regulator perspective.
More robust and cost-effective fastener solutions
Stainless steel fasteners have long been used in corrosive environments, such as within the oil and gas industry, water treatment industry, chemical processing, marine and coastal applications. In recent years, stainless steel materials, predominantly austenitic grades A2 (304) and A4 (316), have become more readily available, largely due to low-cost, high-volume Asian manufacturers.
However, interest in premium stainless steel and high-grade alloy fasteners has increased. Within the correct application, they offer improved product performance, reduced maintenance and can help to maximize product lifecycle.
Particularly in more technical industries where performance, safety and reliability are all critical factors, engineers are now starting to give more consideration to an ever-increasing range of fastener products and material options available to them in an attempt to design more robust and long-term, cost-effective products and infrastructure.
Traditional fastener challenges for engineers
One of the traditional limitations accepted by engineers when considering the use of stainless steel materials is reduced mechanical strength compared with high-tensile carbon steel. If a combination of high strength and corrosion resistance was required, engineers may often resort to high-tensile carbon steel with an additional protective coating.
However, high-tensile carbon steel brings with it the burden of finding a coating suitable for the application and the associated performance, quality and lifespan considerations for the coating. High-tensile carbon steels are also prone hydrogen embrittlement as a result of their manufacturing process. Engineers often express concerns regarding this risk, and careful consideration should always be given during their production.
Corrosion resistance and high strength
Premium high corrosion-resistant stainless steel fasteners are products that combine corrosion resistant capabilities of different stainless steel material grades with the strength of high-tensile carbon steel (such as the BUMAX DX 129 range). In addition, ductility and fatigue properties are also considerably better, outperforming high-tensile carbon steel. By eliminating the limitations of strength in stainless steel materials, these premium fasteners open up new possibilities for design engineers that require a combination of high mechanical performance and corrosion resistance.
Applications for these premium stainless steel fasteners include treatment plants, turbines, aerospace, offshore equipment, steel construction, high-end electric bikes, high-pressure applications, fueling systems and semiconductor manufacturing equipment. Many more applications may follow to the benefit of not only the owners and users of products and infrastructure, but also the entire planet with the potential for the more sustainable use of material resources.
Nimeka de Silva is Development Manager, UK & Ireland, for BUMAX, a leading Swedish specialist manufacturer of premium stainless steel fasteners. Achartered mechanical engineer with an MBA from Aston Business School, Nimeka has experience in engineering, project management and commercial roles across the construction, energy and manufacturing industries.
Patrik Lundström Törnquist is Managing Director of BUMAX. He has more than 20 years of experience from C-level positions in the global mining, steel, manufacturing and engineering industries. He has an M.Sc. from the Chalmers University of Technology and an M.B.A. from the Hult International Business School.