Selection of stainless steel for direct contact with seawater 1

[mrmalcolm]

Clad steels with a clad layer from 316L, 317L or 317LN have been used in the shell of the ship.However, the PREN value of 316L, 317L or 317LN is not higher than 40.In this case, is it appropriate to choose 316L 317L or 317LN with PREN less than 40 as the side shell of the ship with long-term contact with seawater.There is a view that flowing seawater reduces the corrosion hazard and therefore 316 steel can be used for the side shell of a ship. I wonder if any of you have any relevant experience.

Your promote reply will be greatly appreciated.

 

[TugboatEng]

Succesful cladding of offshore structures is typically done with copper nickel or monel. 316 stainless steel works in cases that might see erosive wear of the softer copper alloys and where leakage due to pitting or cracking is inconsequential such as kort nozzles. I do not believe it would ever be accepted as hull cladding. SS is more tolerant when there are other sacrificial materials nearby but if the hull were to have a significant covering of SS then the weaknesses of SS will become very critical.

 

[mrmalcolm]

According to literature，an example of clad steel suitable for the shell of the Arctic ship is steel F36SZП, which has F36SZ as a substrate and a clad layer from 316L or 317LN. These steels show considerably better corrosion resistance over several years compared to plain steel F36SZ (Khaustov, 2006).Can 316L or 317LN come into direct contact with seawater?
Thank you.

 

[TugboatEng]

So you're interested in cladding for ice breaking vessels?

 

[mrmalcolm]

YES.Can stainless clad plates be used as ice belts for icebreakers? If so, which type of stainless steel should be chosen for cladding? Thank you.

 

[EdStainless]

317LMN (S31726) would be the lowest alloy that I would ever consider.
And it should be explosive clad plate.
If there are places that require weld overlay then it must be done in multiple layers to assure the surface chemistry.
The issued isn't seawater exposure per se, it is what happens when there is buildup, marine growth and such.
Oh, and never paint any of the SS.
Then you are into crevice corrosion and things get very bad quickly.
And never take this vessel into hot climates.
You should also look at the 6%Mo alloys such as AL-6XN.
These alloys all have great wear resistance, which is a reason to stay away from CuNi or Monel for ice service.


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P.E. Metallurgy, consulting work welcomed