Stainless steel is favored by the huge desalination industry in the Middle East due to its corrosion resistance and super thermal conductivity. In an exceptionally dry Middle East, where fresh water is scarce, yet the population is growing, drinking water remains a very precious commodity. For decades, the region has relied on desalination processes to provide its inhabitants with valuable fresh water.

The desalination industry is a global industry. Currently, there are more than 17,000 commercial desalination plants in the world, providing usable water to 174 countries. Desalination plants remove salt and minerals from seawater, making it more suitable for human consumption and for agricultural irrigation.

The desalination capacity in the Middle East accounts for more than 60% of the global capacity. Saudi Arabia is the largest producer of desalinated seawater in the region. Because of its corrosion resistance, stainless steel is the equipment material of choice for desalination plants and reverse osmosis plants.

seawater desalination process

Modern desalination plants typically use two processes – distillation or reverse osmosis, and steel is the core material for both.

After being treated by one of these processes, piped seawater is divided into treated water and concentrated brine, which has a higher salinity than raw seawater. The distillation process simulates the water cycle process, and the seawater is evaporated and condensed through heat to achieve purification of seawater. In a reverse osmosis desalination plant, high-pressure water pumps are used to push seawater through a membrane that allows the water to pass through while keeping out salts and other mineral solids.

Due to its corrosion resistance, stainless steel is the material of choice for both desalination plants. Stainless steel’s durability and low maintenance requirements are integral to the success of the desalination industry.

Corrosion resistance of stainless steel

Desalination plants typically use molybdenum-containing duplex stainless steels, such as 2205 and 2304, which have excellent corrosion resistance. Duplex stainless steel also has high mechanical strength, which means that less equipment is used when building equipment, and the overall weight of the desalination plant’s evaporator can be reduced by 30%, which improves economics.

In reverse osmosis desalination plants, corrosion can also be effectively inhibited by using stainless steels containing 6% molybdenum and super duplex stainless steels (eg, 2507 stainless steel used in the Ashkelon desalination plant in Israel).

Although desalination technology continues to advance, stainless steel is still a common material for reliability and corrosion resistance in the desalination industry

New Green Solutions

Desalination is an energy-intensive industry with a huge carbon footprint, and current new innovations in desalination will help the industry become greener. In January 2020, the Saudi government commissioned the British company Solar Water to build the country’s first dome-type solar desalination plant in the “NEOM” new city in the northwest.

Under Solar Water’s solar dome concept, sea water will flow into a hydrological dome constructed of steel and glass, using parabolic mirrors to focus solar radiation onto a steel-framed glass structure. The innovative technology creates a “continuous water cycle” inside the dome with energy equivalent to “up to 20,000 suns”. The corrosion resistance and super thermal conductivity of steel were key to the success of this project.

Looking to the future

As renewable energy solutions emerge, steel will continue to play an important role in desalination as a durable, reliable and highly recyclable material.