The fastest growing process for large-scale desalination plants is Sea-water Reverse Osmosis, SWRO – largely thanks to the development of better and cheaper membranes.
The use of modern stainless steels has helped to cope with these hostile environments, while also increasing the service life of the plants.
|
High pressure pumps
For SWRO we propose 254 SMO or SAF 2507 for the first pass. Lower alloyed grades could be used for feed water with modest chloride content e.g. 2205 for BWRO or 2304 and LDX 2101® for the second pass. Duplex grades would likely be the optimum choice when strength, corrosion resistance and cost are key factors. The material selection charts below helps you choose the right grade for you water. |
 |
High pressure piping
From a corrosion point of view there is no difference between the stainless steel grades used for pumps and high-pressure piping. Experience has shown that grades such as 2205 and 904L are not sufficiently resistant to be used in high-pressure piping in SWRO plants (first pass). For this job, we urge you to choose either SAF 2507 or 254 SMO. Given the high pressures involved, however, the cost-effective choice is duplex SAF 2507. |
|
|
Fujairah, 254SMO HP-piping
|
904L after 5 months use in first pass SWRO |
|
Energy recovery
Although there are several design concepts available for the recovery of energy from the reject, there should be no difference in materials selection philosophy. Brine is just as corrosive as the feed, effectively limiting your choices to 254 SMO or
SAF 2507. Select the latter if high strength is called for.
|
Dweer Energy Recovery system
SAF 2507 Singspring
|
|
Fresh water handling
Use either 1.4307 or 1.4404 depending on the chloride content of the water and the desired safety margins, see material selection chart. Duplex LDX 2101® and 2304 are cost-effective alternatives to both these grades if the design calls for strength, as is the case for large storage tanks. The external environment must also be considered and may occasionally play an important role in materials selection. |
 |