Stainless steel, including duplex and super duplex stainless steel, offers significant economic benefits to the offshore oil and gas industry. Compared to other materials, they are lighter, stronger, more corrosion resistant, and have lower life cycle costs.

Life Cycle Cost:
In addition to longer service life, stainless steel is more qualified for offshore applications due to the increasing emphasis on minimizing life cycle costs (LCC) in building and construction. This concept emphasizes the strong demand for developing new infrastructure that is highly durable and does not require extensive maintenance or repairs. Weight reduction is also a major driver for installing offshore structures. Reduced weight means that the structure is cheaper to build while allowing for the addition of drill pipe and production equipment for the production and exploration of oil and gas.

Steel Grades Used in Offshore Facilities:
SS316L is the main austenitic stainless steel grade used in offshore facilities, which provides enhanced strength at high temperatures and also protects the structure from severe acidic environments. Austenitic grades containing 6% molybdenum are usually used in environments that are permanently immersed in seawater. However, due to the fluctuations in global nickel prices over the past few years, duplex stainless steels have widely replaced austenitic grades. Duplex stainless steels offer an excellent combination of mechanical properties and resistance to stress corrosion cracking, making them ideal for offshore applications. UNS S32205 steel is the most commonly used duplex grade for offshore installations. While duplex stainless steels excel in heavy offshore installations, newer generation super duplex stainless steels are comparable to austenitic stainless steels in terms of seawater corrosion resistance. In addition, these grades offer significantly improved mechanical properties over duplex steels. These super duplex steels feature higher nitrogen, chromium, molybdenum, and nickel contents, which help improve their resistance to pitting and crevice corrosion. Grades such as UNS S32750 and UNS S32760 are used for underwater components in more aggressive offshore installations. While we note that stainless steels are a better alternative to carbon steels, it is key to understand that choosing the best stainless steel grade for a specific need is critical to the cost-effectiveness and durability of offshore installations.

Stainless steel applications offshore
Underwater components: pipes and gratings for oil, sewage, and drainage, risers for oil platforms, heat exchangers for ships and coastal power plants, equipment mounted on the hull.
Platform structural components: pumps, winches, tanks, process vessels, explosion-proof doors, umbilicals, rebars, cable trays, stairs, steps, walkways, gas coolers, gravity separators, etc.
Ship deck components such as ship deck eyelets, anchor brackets, shackles, etc.
Shore (onshore) handrails, ladders, lamp posts, etc.

Ways forward:
Corrosion issues have become a major hurdle for the offshore oil and gas industry. Today, many corrosion-resistant stainless steel alloys have been developed, and the value of duplex stainless steel in offshore applications is obvious to all. With lower nickel content, these high-end duplex stainless steel grades are ideal for developing India's offshore landscape. Considering India's growing fuel demand, the country needs to build a dynamic coastal and offshore infrastructure for offshore projects. This will include the construction of offshore platforms and related logistics, including assistance to coastal infrastructure. Again, as a metal, stainless steel is a model for achieving sustainable and clean energy production.