ASTM G4-01(2014)
(Guide)Standard Guide for Conducting Corrosion Tests in Field Applications (Withdrawn 2023)
Standard Guide for Conducting Corrosion Tests in Field Applications (Withdrawn 2023)
SIGNIFICANCE AND USE
Note 1: This guide is consistent with NACE Standard RP0497.
3.1 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 G15), 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.
3.2 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.
3.3 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.
SCOPE
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.
WITHDRAWN RATIONALE
This guide covered procedures for conducting corrosion tests in plant equipment or systems under operating conditions to evaluate the corrosion resistance of engineering materials. It did not cover electrochemical methods for determining corrosion rates.
Formerly under the jurisdiction of Committee G01 on Corrosion of Metal, this practice was withdrawn in July 2023 in accordance with section 10.6.3 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
General Information
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G4 − 01 (Reapproved 2014)
Standard Guide for
Conducting Corrosion Tests in Field Applications
This standard is issued under the fixed designation G4; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope G30 Practice for Making and Using U-Bend Stress-
Corrosion Test Specimens
1.1 This guide covers procedures for conducting corrosion
G36 Practice for Evaluating Stress-Corrosion-Cracking Re-
tests in plant equipment or systems under operating conditions
sistance of Metals and Alloys in a Boiling Magnesium
to evaluate the corrosion resistance of engineering materials. It
Chloride Solution
does not cover electrochemical methods for determining cor-
G37 Practice for Use of Mattsson’s Solution of pH 7.2 to
rosion rates.
Evaluate the Stress-Corrosion Cracking Susceptibility of
1.1.1 While intended primarily for immersion tests, general
Copper-Zinc Alloys
guidelines provided can be applicable for exposure of test
G41 Practice for Determining Cracking Susceptibility of
specimens in plant atmospheres, provided that placement and
Metals Exposed Under Stress to a Hot Salt Environment
orientation of the test specimens is non-restrictive to air
G44 Practice for Exposure of Metals and Alloys by Alternate
circulation.
Immersion in Neutral 3.5 % Sodium Chloride Solution
1.2 The values stated in SI units are to be regarded as the
G46 Guide for Examination and Evaluation of Pitting Cor-
standard. The values given in parentheses are for information
rosion
only.
G47 Test Method for Determining Susceptibility to Stress-
1.3 This standard does not purport to address all of the
Corrosion Cracking of 2XXX and 7XXX Aluminum
safety concerns, if any, associated with its use. It is the Alloy Products
responsibility of the user of this standard to establish appro-
G58 Practice for Preparation of Stress-Corrosion Test Speci-
priate safety and health practices and determine the applica- mens for Weldments
bility of regulatory limitations prior to use. See also 10.4.2.
G78 Guide for Crevice Corrosion Testing of Iron-Base and
Nickel-Base Stainless Alloys in Seawater and Other
2. Referenced Documents
Chloride-Containing Aqueous Environments
2.2 NACE Standard:
2.1 ASTM Standards:
RP0497 Field Corrosion Evaluation Using Metallic Test
A262 Practices for Detecting Susceptibility to Intergranular
Specimens
Attack in Austenitic Stainless Steels
E3 Guide for Preparation of Metallographic Specimens
3. Significance and Use
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
NOTE 1—This guide is consistent with NACE Standard RP0497.
sion Test Specimens
3.1 Observations and data derived from corrosion testing
G15 Terminology Relating to Corrosion and Corrosion Test-
are used to determine the average rate of corrosion or other
ing (Withdrawn 2010)
types of attack, or both (see Terminology G15), that occur
G16 Guide for Applying Statistics to Analysis of Corrosion
during the exposure interval. The data may be used as part of
Data
an evaluation of candidate materials of construction for use in
similar service or for replacement materials in existing facili-
ties.
This guide is under the jurisdiction of ASTM Committee G01 on Corrosion of
3.2 The data developed from in-plant tests may also be used
Metals and is the direct responsibility of Subcommittee G01.14 on Corrosion of
Metals in Construction Materials.
as guide lines to the behavior of existing plant materials for the
Current edition approved Nov. 1, 2014. Published November 2014. Originally
purpose of scheduling maintenance and repairs.
approved in 1968. Last previous edition approved in 2008 as G4–01 (2008). DOI:
10.1520/G0004-01R14.
3.3 Corrosion rate data derived from a single exposure
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
generally do not provide information on corrosion rate change
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
The last approved version of this historical standard is referenced on Available from NACE International (NACE), 1440 South Creek Dr., Houston,
www.astm.org. TX 77084-4906, http://www.nace.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G4 − 01 (2014)
versus time. Corrosion rates may increase, decrease, or remain 4.7.4 Parting or dealloying is a condition in which one
constant, depending on the nature of the corrosion products and constituent is selectively removed from an alloy, as in the
the effects of incubation time required at the onset of pitting or dezincification of brass or the graphitic corrosion of cast iron.
crevice corrosion. Close attention and a more sophisticated evaluation than a
simple mass loss measurement are required to detect this
phenomenon.
4. Limitations
4.7.5 Pitting corrosion cannot be evaluated by mass loss. It
4.1 Metal specimens immersed in a specific liquid may not
is possible to miss the phenomenon altogether when using
corrode at the same rate or in the same manner as in equipment
small test specimens since the occurrence of pitting is often a
in which the metal acts as a heat transfer medium in heating or
statistical phenomenon and its incidence can be directly related
cooling the liquid. In certain services, the corrosion of heat-
to the area of metal exposed.
exchanger tubes may be quite different from that of the shell or
4.7.6 Stress-corrosion cracking (SCC) may occur under
heads. This phenomenon also occurs on specimens exposed in
conditions of tensile stress and it may or may not be visible to
gas streams from which water or other corrodents condense on
the naked eye or on casual inspection. A metallographic
cool surfaces. Such factors must be considered in both design
examination (Practice E3) will confirm this mechanism of
and interpretation of plant tests.
attack. SCC usually occurs with no significant loss in mass of
4.2 Effects caused by high velocity, abrasive ingredients,
the test specimen, except in some refractory metals.
etc. (which may be emphasized in pipe elbows, pumps, etc.)
4.7.7 A number of reactive metals, most notably titanium
may not be easily reproduced in simple corrosion tests.
and zirconium, develop strongly adherent corrosion product
films in corrosive environments. In many cases, there is no
4.3 The behavior of certain metals and alloys may be
acceptable method to remove the film without removing
profoundly influenced by the presence of dissolved oxygen. It
significant uncorroded metal. In these cases, the extent of
is essential that the test specimens be placed in locations
corrosion can best be measured as a mass gain rather than mass
representative of the degree of aeration normally encountered
loss.
in the process.
4.7.8 Some materials may suffer accelerated corrosion at
4.4 Corrosion products from the test specimens may have
liquid to atmospheric transition zones. The use of small test
undesirable effects on the process stream and should be
specimens may not adequately cover this region.
evaluated before the test.
4.5 Corrosion products from the plant equipment may
5. Test Specimen Design
influence the corrosion of one or more of the test metals. For
5.1 Before the size, shape, and finish of test specimens are
example, when aluminum specimens are exposed in copper-
specified, the objectives of the test program should be
containing systems, corroding copper will exert an adverse
determined, taking into consideration any restrictions that
effect on the corrosion of the aluminum. On the contrary,
might dictate fabrication requirements. The duration, cost,
stainless steel specimens may have their corrosion resistance
confidence level, and expected results affect the choice of the
enhanced by the presence of the oxidizing cupric ions.
shape, finish, and cost of the specimen.
4.6 The accumulation of corrosion products can sometimes
5.1.1 Test specimens are generally fabricated into disks or
have harmful effects. For example, copper corroding in inter-
rectangular shapes. Other shapes such as balls, cylinders, and
mediate strengths of sulfuric acid will have its corrosion rate
tubes are used, but to a much lesser extent.
increased as the cupric ion concentration in the acid increases.
5.1.2 Disks are normally made by one of three methods: (1)
by punching from sheet material, (2) by slicing from a bar, or
4.7 Tests covered by this guide are predominantly designed
(3) by trepanning by a lathe or mill. Punched disks are by far
to investigate general corrosion; however, other forms of
the least expensive and should be considered if material
corrosion may be evaluated.
thickness is not a limitation. Some of the positive characteris-
4.7.1 Galvanic corrosion may be investigated by special
tics of disks are: (1) the surface area can be minimized where
devices that couple one specimen to another in electrical
there is restricted space, such as in pipeline applications, (2)
contact. It should be observed, however, that galvanic corro-
disks can be made inexpensively if a polished or machined
sion can be greatly affected by the area ratios of the respective
surface finish is not required, and (3) edge effects are mini-
metals.
mized for a given total surface area. Some negative character-
4.7.2 Crevice or concentration cell corrosion may occur
istics are: (1) disks are very costly to fabricate if a ground finish
when the metal surface is partially blocked from the bulk
and machined edges are required, (2) disks fabricated from
liquid, as under a spacer. An accumulation of bulky corrosion
sheet material result in a considerable amount of scrap
products between specimens can promote localized corrosion
material, and (3) disks sliced from a bar present a surface
of some alloys or affect the general corrosion rates of others.
orientation that can result in extensive end-grain attack. Using
Such accumulation should be reported.
a bar is undesirable unless end-grain effects are to be evaluated.
4.7.3 Selective corrosion at the grain boundaries (for
example, intergranular corrosion of sensitized austenitic stain- 5.2 Rectangular specimens are fabricated by either
less steels) will not be readily observable in mass loss punching, shearing, or saw cutting. Punched disk shaped
measurements and often requires microscopic examination of specimens are the most economical if the quantity is suffi-
the specimens after exposure. ciently high to justify the initial die cost. Fabrication is more
G4 − 01 (2014)
cost-effective for rectangular specimens than for disks when heat affected zone. For example, gas tungsten arc welding has
ground finished and machined sides are required, and they can lower heat input than oxygen fuel welding and causes a
be made using very few shop tools. In some cases, rectangular narrower heat affected zone, which is also closer to the weld
specimens are more awkward to mount. bead.
5.3 Material availability and machinability also affect the
7. Preparation of Test Specimens
cost of producing all types of specimens. Before the shape and
size are specified, the corrosion engineer should determine the
7.1 Controversy exists as to whether the test specimen edges
characteristics of the proposed materials.
should be machined. The cold-worked area caused by shearing
or punching operations can provide valuable information on
6. Test Specimens
alloy susceptibility to stress corrosion cracking. Also, the
6.1 The size and shape of test specimens are influenced by
ability to compare information among specimens of different
several factors and cannot be rigidly defined. Sufficient thick-
materials can be affected by the amount of cold work per-
ness should be employed to minimize the possibility of
formed on the material. Therefore, the decision to machine and
perforation of the specimen during the test exposure. The size
to test specimens with/without the residual stresses associated
of the specimen should be as large as can be conveniently
with cold work should be made on a case-to-case basis.
handled, the limitation being imposed by the capacity of the
7.1.1 The depth of cold work associated with punching and
available analytical balance and by the problem of effecting
shearing operations typically extends back from the cut edge to
entry into operating equipment.
a distance equal to the specimen thickness. Removal of the
6.2 A convenient size for a standard corrosion disk shaped
cold worked areas can be performed by grinding or careful
specimen is 38 mm (1.5 in.) in diameter and 3 mm (0.125 in.)
machining the specimen edges.
in thickness with an 11 mm (0.438 in.) hole in the center of the
7.1.2 Ideally, the surface finish of the specimen should
round specimen. This size was arrived at as being the maxi-
replicate that of the surface finish of the material to be used for
mum size that could easily effect entry through a normal 38
equipment fabrication. However, this is often difficult because
mm nozzle. However, it is also convenient for larger size
the finish on materials varies between mills, between sheet and
nozzle entries as well as for laboratory corrosion testing. A
plate and even between heat treatments. The mill scale and the
convenient standard specimen for spool-type racks measures
amount of oxides on the surface can vary as well. Also, surface
25 by 50 by 3 mm (1 by 2 by 0.125 in.) or 50 by 50 by 3 mm
finishes are difficult to apply to edges that have been distorted
(2 by 2 by 0.125 in.). A round specimen of 53 by 3 mm (2 by
by punching or shearing. Since the primary requirement is
0.125 in.) or 55 by 1.5 mm (2 by 0.062 in.) is sometimes
usually to determine the corrosion resistance of the material
employed. These last three measure about 0.005 dm in surface
itself, a clean metal surface is most often used. The purpose of
area.
the test dictates the required finish of the specimen. For
6.3 Other sizes, shapes, and thicknesses of specimens can be
instance, for water treating applications, relative changes of
used for special purposes or to comply with the design of a
weights of specimens are usually compared to optimize inhibi-
special type of corrosion rack. Special designs should be
tor additions. The specimens are generally punched or sheared
reduced to a few in number in preliminary tests; special designs
and finished by blasts with glass beads. This is one of the most
should be employed to consider the effect of s
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