Nemmeli Seawater Desalination Plant, Chennai, India (Image Courtsey : VA Tech Wabgh)

Desalination plants and stainless steels to grow further

Desalination is growing at a phenomenal pace, thus representing a major opportunity for stainless steel suppliers. The Indian desalination market is comparatively new and in the development stage of its life cycle. Given that thirst for water is increasing and the amount of water in the world remains constant, desalination and water treatment in general look set to remain growth industries.
^ Nemmeli Seawater Desalination Plant, Chennai, India (Image Courtsey : VA Tech Wabgh)

Article by Nirmal Mathur

India is likely to face severe water crisis by 2030 as the demand is likely to be double that of the available supply. In fact, 21 Indian cities are likely to run out of ground water by 2020 itself. In a recent study done by NITI (National Institution for Transforming India), a policy think tank of the Government of India has warned that India is facing its ‘worst’ water crisis in its history and that demand for potable water will outstrip supply by 2030 if steps are not taken. The same report also suggested that nearly 600 million Indians face high to extreme water stress and about 200,000 people die every year due to inadequate access to safe water.

India’s booming population and rapidly expanding urban areas have extracted a huge toll on its rivers, which are badly polluted and choked by development. India, a nation whose population has nearly doubled in the past 40 years to 1.35 billion, has seen unplanned growth lead to the use of water bodies as dumping grounds for sewage and industrial effluents.

Owing to India‘s large coastline, desalination is considered one of the most viable water supply alternatives. Desalination is a process of removing excess salts and minerals from the water to make it fit for human consumption. India has a huge untapped potential for the desalination market. For instance, one of the coastal metro cities, Mumbai, which has to depend on lakes and rainwater, has a water requirement that currently stands at 3,900 MLD (million litres daily) and is projected to reach 13,000 MLD by 2026.

Such increases in demand for water pose a challenge to the state and national governments in striking a balance to satisfy water needs among various entities such as industries, agriculture, and domestic.

In a recent survey, it was reported that over the past few years, the global water desalination industry has risen rapidly to reach 99.8 million cubic meters per day in 2017. India does have some indigenous rivers which lead to adequacy in water supply in many locales of the country.

However, major states like Rajasthan, Gujarat and Tamil Nadu are facing severe water crisis which presses the need for water desalination in the coastal areas of these states. India already has many installations for sea water desalination some of which are very big in size.

Material grades

Presently, another coastal metro city, Chennai, fulfils around 30 per cent of its water demand by desalination. Even now it already experiences a shortfall of around 300,000 m3/ day, but the government is convinced that desalination is the road ahead. There is therefore a major opportunity for stainless steel suppliers in desalination plants. As long as the water industry remains aware of the favourable life-cycle costs of stainless steel, the opportunities for suppliers of stainless steel, and especially of duplex grades, can only increase. Within desalination projects stainless steel is mostly used in piping but also has applications in the form of pumps and valves.

Desalination plants are known to be very severe environments due to the high chloride, high temperature conditions. In the past, austenitic stainless steels in the ASTM 300 series tended to be the material of choice for desalination. In cases in which even higher corrosion resistance has been needed, the typical material solution has been higher alloyed austenitic grades that go beyond the 300 series, such as austenitic 6Mo grades (UNS NO 8367).  More recently, duplex grade 2205 (UNS S32205/S31803) and other duplex stainless steels have emerged as the more optimal material in many situations.

Duplex 2205 and other duplex stainless steels have gained in popularity in the desalination industry for a number of reasons. First, duplex steels have good corrosion resistance and in many cases can be offered at a cost saving over the comparable austenitic steel. For example, duplex 2205 has similar pitting and crevice corrosion properties to 904L (UNS NO8904), but is available at a lower cost due to the fact that its chemical composition includes lower percentages of expensive metals.

In addition, duplex steels have high strength. Specifically, the strength of duplex 2205 is nearly double that of austenitic steels. Thus, less weight of material is typically needed which can lead to further cost savings. The global desalination market is likely to hit USD 52.4 billion by 2020. With depleting freshwater sources and rapid industrialisation, coupled with urbanisation, growth in the desalination industry in India is likely to pick up.


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