ASTM G4-01(2008)

Note 1—This guide is consistent with NACE Standard RP0497.

Observations and data derived from corrosion testing are used to determine the average rate of corrosion or other types of attack, or both (see Terminology G 15), that occur during the exposure interval. The data may be used as part of an evaluation of candidate materials of construction for use in similar service or for replacement materials in existing facilities.

The data developed from in-plant tests may also be used as guide lines to the behavior of existing plant materials for the purpose of scheduling maintenance and repairs.

Corrosion rate data derived from a single exposure generally do not provide information on corrosion rate change versus time. Corrosion rates may increase, decrease, or remain constant, depending on the nature of the corrosion products and the effects of incubation time required at the onset of pitting or crevice corrosion.

1.1 This guide covers procedures for conducting corrosion tests in plant equipment or systems under operating conditions to evaluate the corrosion resistance of engineering materials. It does not cover electrochemical methods for determining corrosion rates.

1.1.1 While intended primarily for immersion tests, general guidelines provided can be applicable for exposure of test specimens in plant atmospheres, provided that placement and orientation of the test specimens is non-restrictive to air circulation.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See also 10.4.2.