The marine environment is recognised as the most corrosive natural environment, and designers have problems selecting materials that will give good performance at reasonable cost. Not simply because of the corrosivity of seawater but because of many factors such as marine fouling, velocity of flow and aeration which have to be considered in making the optimum technical/economic choice. Nickel containing alloys such as cupronickels, austenitic stainless steels and nickel base alloys are increasingly being used in seawater and marine applications because of their resistance to pitting and crevice corrosion. Typical applications for nickel alloys in these environments are pumps, valves, propeller shafts, exhaust systems, piping systems, tanks, heat exchangers, fasteners, bellows, and desalination equipment.
The following papers review factors influencing selection of marine and seawater materials and how they are satisfied by nickel-containing alloys in some major applications.
We also regularly publish articles on Nickel in the Stainless Steel World magazine like the one below.
Super austenitic stainless steel B66
By Hervé Le Guyader, Valérie Debout, Anne-Marie Grolleau and Nicolas Dolignon, CETEC DCN Cherbourg.
Franck Demulder, DCN Engineering Cherbourg
The use of corrosion resistant stainless steels and alloys increases in marine technologies (offshore , desalinisation, marines civil and military applications). This is due to the increasing severity of corrosive environments and to the increased reliability requirements for the equipments. Natural sea water appears particularly corrosive for stainless steels and only highly alloyed stainless steels can give satisfaction. DCN has an important feedback on 2507 superduplex UNS S32550, S32750, and on NiCrMo alloys, especially alloy 625 (UNS N06625) and alloy A59 (UNS N06059). These NiCrMo alloys and 2507 superduplex were used for sea water piping after various studies of corrosion resistance in sea water (ref 1 and 2). A new stainless steel B66 (UNS S31266), seems to present very interesting performances for marine applications. DCN performed a first evaluation of this alloy (on forgings) for application in sea water piping, on the basis of its knowledges of study and use of 2507 superduplex, alloy 625 and alloy A59 (ref 1 and 2).
To read the whole article, click here (PDF, 2115KB). This article was originally published in the Stainless Steel World March 2006 edition.
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