How can sea water corrode stainless steel pumps?

Many people give priority to stainless steel pumps when pumping seawater or saturated salt water. They feel that the stainless steel is durable and will not require any maintenance, but it is found that the damage is faster when used, and the stainless steel pump is seriously corroded.

In fact, seawater is a very complex multi-component aqueous solution. The main elements in seawater are Na ion, K ion, CL ion, SO4 ion, etc., and most of these elements are above 1 mg.

Various authoritative books have strict requirements on the corrosion of stainless steel in the CL ion environment: the content of CL ions should be less than 25ppm, otherwise stress corrosion, pitting corrosion and intergranular corrosion will occur. The content of CL ions in seawater is more than 1mg, which far exceeds the content requirements for stainless steel corrosion. Therefore, in general, stainless steel is not recommended for seawater pumps.

If stainless steel has been selected, it is recommended to add an appropriate corrosion inhibitor or consider replacing it with a plastic pump if the process conditions permit. The use of fluoroplastics to pump seawater not only has good resistance to seawater corrosion, but also reduces the cost of use.