Laboratory immersion corrosion testing metals ASTM

Factors may throw off these rates—these are outlined in ASTM G3I, Standard Practice for Laboratory Immersion Corrosion Testing of Metals. Coupon-type tests cannot be correlated with changing plant conditions that may dramaticahy affect process equipment lifetimes. Other methods must be used if more frequent measurements are desired or correlation with plant conditions are necessary. 

G31-72, Standard practice for laboratory immersion corrosion testing of metals. Annual Book of ASTM Standards, ASTM International, Philadelphia, Pa., 2000, p. 99, Vol. 3.02. 

ASTM G31-72 (1985) Standard Practice for Laboratory Immersion Corrosion Testing of Metals. 

ASTM G 31, Practice for Laboratory Immersion Corrosion Testing of Metals—This method describes typical test vessels, metal specimens (coupons), process controls, aeration techniques, coupon placement and supports, exposure times, and corrosion rate calculations. 

ASTM G 31 Standard Practice for Laboratory Immersion Corrosion Testing of Metals Describes procedures for conducting laboratoiy weight loss tests Provides information on reporting and factors to be aware of. 

Exposure of coupons to the solution of interest with posttest evaluation according to accepted standards, such as ASTM G 31, Practice for Laboratory Immersion Corrosion Testing of Metals, is the most directly applicable method of testing in organic liquids. Because of the general lack of data on corrosion in organic liquids, coupon testing often... 

ASTM Designation G31. Annual Book of Standards, Vol. 03, 02. Laboratory Immersion Corrosion Testing of Metals. (American Society for Testing of Materials, 2001)... 

The basic in vitro tests derived from teehnieal applications are the salt spray test (ASTM B-117) and the submersion test, performed in saline solutions (3.5% NaCl, ASTM G31-72 (2004) Standard Practice for Laboratory Immersion Corrosion Testing of Metals). Both tests are conducted at room temperature. By such tests the mass loss ean be determined according to equation (10.5). The mass loss is calculated after removing the corrosion products with chromic acid, which at the same time removes the corrosion products and inhibits further corrosion (Forking, 1964), which is suitable for technical applications but may raise problems in biological environments. 

A common chemical laboratory test for corrosion resistance is a simple exposure test using metal coupons. The ASTM standard G48 —Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution—describes a simple exposure test. The material coupons (e.g., 60 x 60 mm) are placed on a glass cradle and immersed in the solution in such a way that the coupons are evenly exposed. 

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... 

While many laboratory tests for resistance of metals to stress corrosion cracking have been developed, only a few tests are amenable to actual in-situ testing in seawater. These primarily consist of the exposure of statically stressed type test specimens such as described in ASTM G 30, G 38, G 39, and ISO 7539-2, ISO 7539-3, and ISO 7539-5. In addition, welded specimens such as described in ASTM G 58 are excellent for evaluation of the stress corrosion resistance of weldments in simple immersion tests. Evaluation of corrosion fatigue is usually limited to laboratory testing. 

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