Articles on the application of duplex stainless steels

Sluice gates are movable barriers that regulate water levels and flow rates in waterways. In a world of changing climate and increased flooding risks, these gates need to be taller and stronger than ever before. Thanks to their strength and corrosion resistance, molybdenum- containing duplex stainless steels are the ideal construction material.

Most 3D printed objects are less than 30 cm long. So, how is the 10 m long Oregon Dragon Bench possible? Instead of using powder, the bench was built layer by layer applying a robotic welding technology called "WAAM". Made with 2209 duplex stainless steel weld wire, the Oregon Dragon Bench exemplifies how 3D printed metal structures can do more with less.

The historic center of Stockholm, Sweden, stretches over 14 islands. The bridges that connect these islands are in constant use, so any maintenance closures cut off vital transportation arteries. A solution that spares future generations from disruption was therefore crucial for the renovation of the city's busiest rail bridges: the four Söderströms. The new molybdenum-containing duplex stainless steel superstructure will provide enough strength and corrosion resistance to outlast the 120-year design life, with minimal upkeep.

The largest private development in US history, Hudson Yards boasts a modern, sustainable design. Its prime location near the Hudson River in New York City comes at the price of exposure to both marine and de-icing salts. With corrosion resistance in mind, stainless steel emerges as an integral part of the mini-city, most notably in an interactive centerpiece called the "Vessel."

Groundbreaking robots in the UK eliminate the logistical and environmental impacts of gas line excavation by taking measurements from inside the pipe. To withstand the extreme conditions there, 2507 super-duplex stainless steel was chosen for the robots' chassis.

Building high-performance boats requires strong materials. Typically, stainless steel is not even under consideration for ship construction, but that may be changing. In fact, governments and businesses the world over are starting to take an interest in a new, low-maintenance and environmentally friendly ship hull, built entirely from high-strength, molybdenum-containing super- and hyper-duplex stainless steel, at no additional cost.

Like a net frozen in mid-air, a striking footbridge in southern Germany is making a statement about minimalism. This gossamer structure is only possible thanks to the unique characteristics of 2205 duplex stainless steel.

Deep within the Tarim Basin of Xinjiang, China, pipelines transport natural gas as it is extracted and refined for distribution throughout the country. However, gas leakage has been a recurrent issue as a result of pipeline corrosion. Enter the 'Pipeline Dragon': constructed entirely of molybdenum-containing 2205 duplex stainless steel, a new pipeline promises to reduce gas leakage, preventing environmental disaster while conserving resources. At 4,500 tonnes, it is the largest single order of duplex stainless steel in China to date.

At the ends of the earth, strange machines patrol the oceans in search of oil deposits to drill for. Meanwhile, their cousins stand tall in some of the world's gustiest seas, installing or maintinaining offshore wind turbines. Both of these highly specialized vessels, lifted up by jackup legs, brave extreme conditions on the sea to help meet our global energy demand. But constant exposure to high winds and enormous waves means 'jackups' must be made of strong materials. Molybdenum-containing steel allows these special machines to stand up to the forces of nature, while ensuring the safety of the people who work and live onboard them.

In the Louvre Abu Dhabi, stainless steel not only protects precious artwork, but becomes art itself. The museum's breathtaking roof contains molybdenum to withstand one of the world's most corrosive environments. Inside, rays of sunlight dance across surfaces, creating a spectacle unlike any other.

Beneath the surface, under streets and buildings, an 'invisible' infrastructure humbly helps to make modern life more efficient, convenient and safe; pipelines that transport drinking water, gas, oil and waste water to and from buildings and across cities, countries and continents. Burying these pipes underground protects them from most forms of damage, and saves space above ground. However, ageing, corrosion, wear and ground movement pose challenges to their integrity, and can lead to leaks which are difficult to locate, access and fix. A rubber pipe seal, secured in place from inside the pipe with molybdenum-containing stainless steel expansion rings, is a convenient and durable solution.

Chemical tankers are specialized ships carrying liquid cargoes that may be environmentally hazardous, flammable or highly reactive. They are designed and operated under special rules, and increasingly have built-in molybdenum-containing stainless steel tanks. Sailing around the world, they transport liquid goods safely over long distances. They represent a significant market for duplex stainless steels and molybdenum.

Iconic bridges that combine cutting edge technology and aesthetic beauty are increasingly used to create visual focal points in city centers, but very few are constructed on modest budgets and ahead of schedule.

Offshore oil and gas platforms see some of the most demanding environmental conditions for construction materials anywhere. Exposed to extreme weather, wind and waves, these structures must operate safely for decades. The most challenging sites are located in or near the Arctic oceans, where frequent storms intensify the extremely corrosive exposure to seawater. Molybdenum-containing alloys, especially duplex and super duplex stainless steels, last longer than almost all other materials in these difficult situations. One small but critical example is super duplex bolts.

Repair sleeves are found in the tool box of virtually every water utility. They allow quick repair of leaking water pipes without replacing them. Often fabricated from molybdenum-grade Type 316 stainless steel, they reduce water wastage and are yet another way that molybdenum helps sustain Earth’s resources.

Duplex stainless steel storage tanks are increasingly being used due to their long, low-maintenance service life. Surprisingly, they can also reduce initial costs for tank owners. The higher strength of duplex grades permits thinner walls requiring less steel. Because costly protective coatings or cathodic protection are not necessary, they can compete on installed cost with carbon steel tanks.

Maritime shipping remains one of the most cost-efficient global transport methods, especially compared with air freight. Its rapid growth since the 1970s and the containerisation of cargo have kept pace with the global economy, however this has also increased its environmental impact. New regulations limiting the sulfur content of engine fuel mean that ships must either use cleaner, more expensive fuel, or install equipment to take sulfur out of exhaust gases, a process in which molybdenum plays a key role.

It can be difficult and time consuming for engineers to find materials properties beyond the basic ones reported in producer data sheets. This is especially true for lesser-used high-performance alloys. The new High-Performance Alloys Database addresses this problem. It contains a large number of materials properties for each of the 100 or so featured alloys, many involving molybdenum.

The iconic New York City skyline is celebrated in movies and photos. But as a global financial, cultural and business center, it is also constantly changing – particularly now. Buildings are rising at a breathtaking pace and many feature sustainable designs. Molybdenum-containing stainless steel is often key to making them not only beautiful, but also resilient and durable, thus reducing their carbon footprint.

The propeller shaft may be the most important component of any motorized vessel. It drives the propeller, hour after hour, day after day. Molybdenum provides improved strength and corrosion resistance in several high-performance stainless steel grades used in demanding shaft applications.

Nuclear power currently supplies some 11% of the world’s energy needs. Without debating its pros and cons, everyone would agree that the spent fuel already in existence from more than 50 years of generation needs safe handling and disposal. Imparting greatly increased corrosion resistance to stainless steel, molybdenum is making a positive contribution to the ongoing safety of spent fuel management throughout the world.

Dental instruments need to be hard for the dentist to work efficiently and precisely, and tough enough not to break during procedures. At the same time they have to be hygienic, corrosion resistant and easily sterilized. The molybdenum-containing hardenable surgical stainless steel Type 440A fits these requirements and new, even harder and tougher grades are on the horizon.

Since its dedication in New York harbor on October 28, 1886, The Statue of Liberty has become one of the world’s best-known sculptures. However, after nearly 100 years in the aggressive marine environment, galvanic corrosion between the iron framework and the copper skin caused major structural deterioration. Molybdenum-containing stainless steel played a crucial role in restoring this iconic landmark.

Canadian-born California architect Frank Gehry’s project for Fondation Louis Vuitton exhibits unprecedented aesthetic innovation and technological sophistication. The spectacular glass sails of the roof appear so light and airy, in large part, thanks to the delicate high-strength molybdenum-containing duplex stainless steel support structure.

Wireline is cable used to lower oil- and gas-well tools and measuring equipment downhole. Wireline must be strong, dependable and resistant to the increasingly corrosive conditions encountered in today’s deeper wells. Molybdenum imparts the required corrosion resistance to the stainless steel and nickel alloys used in this application.

Decorative stainless steel panels are widely used in façades, roofs and elevators because they are attractive and long-lasting. Increasingly, engineers now use stainless steel for load-bearing structures in challenging environments. In many cases stainless steel is cost-effective if the whole life cycle of the installation is considered.

A recent study found that about one quarter of the molybdenum used each year is recycled material from scrap sources. The rest is newly mined, primary molybdenum. Scrap therefore plays an important role in meeting demand and contributing to sustainability.

Material longevity and its inherent impact on long-term project sustainability are changing the way buildings are designed. Memorials like the new Four Freedoms Park in New York have to last for hundreds of years. Corrosion resistant 2205 duplex stainless steel was necessary so that the sculptural handrails were as durable as the massive blocks of granite in this highly-acclaimed new monument.

A major historic ship preservation project is currently under way in Stockholm.  The galvanized and epoxy coated mild steel bolts used to hold the ship together after it was raised are failing due to corrosion. Molybdenum is a key alloying element in the high-strength, corrosion-resistant super duplex stainless steel Sandvik SAF 2507TM and Sandvik SAF 2707 HDTM bolts that will hold the great ship Vasa together to achieve a minimum design life of 100 years.