S32205 (2205) and UNS S31803 (2203) duplex stainless steels have some overlapping applications, but their specific properties make them suitable for different industries and environments. The following are typical applications for each grade:

Offshore and marine environments: Offshore oil and gas platforms
Subsea equipment and pipelines
Desalination plants and seawater intake systems
Coastal and port infrastructure (e.g. piers, docks, breakwaters)

Chemical and Petrochemical Processing: Containers, tanks and piping for chemical plants
Equipment for handling corrosive chemicals and corrosive liquids
Refineries and petrochemical facilities

Pulp and Paper Industry: Digesters, evaporators and other process equipment
Pipes and valves for pulp and paper mills

Water and wastewater treatment: Desalination plant components
Wastewater treatment equipment
drinking water distribution system

Power generation: Nuclear power plant components
Coal-fired power plant flue gas desulfurization system
Geothermal power plant equipment

General industrial applications: Process equipment, storage tanks and pipelines for various industries
Architectural and decorative elements
Household appliances and kitchen equipment

Food and Beverage Processing: Equipment, tanks and piping for food, dairy and beverage plants
Food processing machinery and equipment

Pharmaceutical and Biomedical: Medical equipment, surgical equipment and laboratory equipment
Pharmaceutical processing equipment

Low and high temperature applications: Liquefied Natural Gas (LNG) Facilities
Petrochemical plants and power generation equipment

S32205 is the first choice for more corrosive and demanding environments, such as the offshore, chemical and water treatment industries, where its superior corrosion resistance and mechanical properties are critical.
S31803 is more commonly used in general industrial, food and beverage, and pharmaceutical applications, where its slightly lower corrosion resistance and mechanical properties are acceptable, and its lower cost is an advantage.