Seawater corrosion testing

The number of replicate test specimens depends upon the desired reliability of the results of the test. ASTM G 16 gives guidance for establishing the required number of replicate specimens. In general, as recommended in ASTM G 52, triplicate specimens for each exposure period are sufficient for many seawater corrosion tests. 

Biain, R. M., Adamson, W. L., and Weber, B., Corrosion Coupon in Natural Waters A Case History Dealing with Reverse Osmosis Desalination of Seawater, Corrosion Testing in Natural Waters Second Volume. ASTM STP 1300,1997, pp. 122-142. 

Vanadium is resistant to attack by hydrochloric or dilute sulfuric acid and to alkali solutions. It is also quite resistant to corrosion by seawater but is reactive toward nitric, hydrofluoric, or concentrated sulfuric acids. Galvanic corrosion tests mn in simulated seawater indicate that vanadium is anodic with respect to stainless steel and copper but cathodic to aluminum and magnesium. Vanadium exhibits corrosion resistance to Hquid metals, eg, bismuth and low oxygen sodium. 

Guide for crevice corrosion testing of iron base and nickel base stainless steels in seawater and other chloride-containing aqueous environments... 

The impetus for further developments was the recognition of the economic significance of corrosion phenomenon during the 19th century that led the British Association for the Advancement of Science to sponsor corrosion testing projects such as the corrosion of cast and wrought iron in river and seawater atmospheres in 1837. Early academic interest in corrosion phenomenon (up to the First World War) was followed by industrial interest due to the occurrence of equipment failures. An example of this is the corrosion-related failure of condenser tubes as reported by the Institute of Metals and the British Non-ferrous Metals Research Association in 1911. This initiative led to the development of new corrosion-resistant alloys, and the corrosion related failure of condenser tubes in the Second World War was an insignificant problem. 

Media considerations. SCC tests can be divided into those conducted in natural environments, such as atmospheric exposure tests and seawater immersion tests, and those which are conducted under laboratory conditions or other fabricating operations. The principal disadvantage of atmospheric exposure tests is the comparatively long time required for their completion however, they are reliable since they can reflect the projected use. There is a standard practice for evaluating stress-corrosion cracking resistance of metals and alloys by alternate immersion in a solution of NaCl 3.5%, pH 6.5. For spray testing, ASTM B-117, 2003 states the relevant conditions for conducting the test. (ASTM G44)4... 

Guide for Crevice Corrosion Testing of Iron-Base and Nickel-Base Stainless Alloys in Seawater and Other Chloride-Containing Aqueous Environments, G 78, Annual Book of ASTMStandards, ASTM, 1992, p 463-470... 

TABLE 3— Results of crevice corrosion tests in natural seawater from the LaQue Center for Coirosion Technology, circa 1993 [77]. 

Kain, R. M., Crevice Corrosion Testing in Natural Seawater Significance and Use of Multiple Crevice Assemblies, Journal ofTestingandEvaluation, Vol. 18, No. 5,1990, pp. 309-318. 

OO] Dmgli, J. M. and Johnsen, R., Corrosion Testing of Stainless Steel Weldments in Seawater, NaCl- and FeCl3 Solutions, Paper 410, NACE CORROSION/88, St. Louis, MO, 1988. 

Wilde, B. E., A Critical Appraisal of Some Popular Laboratory Electrochemical Test for Predicting the Localized Corrosion Resistance of Stainless Alloys in Seawater, Corrosion, Vol. 28, No. 8, 1972, pp. 283-291. 

FIG. 1—Sequence of events (left to right) in a stress corrosion test on an iniUatty smooth specimen. For low-alloy steels In seawater, the rale of growth of SCC is faster than it is for pitting by a factor of about 106, and fast fracture propagates at about 1010 times faster than SCC [0]. 

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