Previous studies, in sea water containing oxygen levels of 65,150 and 750ppb at 90°C, have shown the suitability of thin walled, laser welded UNS S34565 stainless steel tubing for MSF desalination plant evaporators. However, in the tests carried out, some galvanic corrosion was observed on UNS S32760 super duplex stainless steel tubeplate
material. Further work has been carried out to study the use of UNS S31603 and S34565 as tubeplate material in these environments. Results show welded tube-tubeplate assemblies to be suitable with all materials tested; with rolled tube-tubeplate joints slight corrosion was observed, the extent being a function of the oxygen level.
Keywords: stainless steel, laser welding, sea water, MSF desalination, galvanic corrosion