ASTM G52-00
(Practice)Standard Practice for Exposing and Evaluating Metals and Alloys in Surface Seawater
Standard Practice for Exposing and Evaluating Metals and Alloys in Surface Seawater
SCOPE
1.1 This practice covers conditions for exposure of metals and alloys to surface seawater, and sets forth the general procedures that should be followed in conducting seawater exposures tests so that meaningful comparisons may be made for different locations.
1.2 This practice lists suggested procedures for the evaluation of the effects of seawater on metals and alloys. Note 1-Terms relative to this subject matter can be found in Terminology G15.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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.
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Designation:G52–00
Standard Practice for
Exposing and Evaluating Metals and Alloys in Surface
Seawater
ThisstandardisissuedunderthefixeddesignationG 52;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope G 39 PracticeforPreparationandUseofBent-BeamStress-
Corrosion Test Specimens
1.1 As contrasted with deep ocean testing (1), this practice
G 46 Guide for Examination and Evaluation of Pitting
covers conditions for the exposure of metals, alloys, and other
Corrosion
materials in natural surface seawater such as those typically
G 58 Practice for Preparation of Stress-Corrosion Test
found in bays, harbors, channels, and so forth (2, 3). This
Specimens for Weldments
practice covers full immersion, tidal zone and related splash,
G 78 Guide for Crevice Corrosion Testing of Iron Base and
and spray zone exposures.
Nickel Base Stainless Alloys in Seawater and Other
1.2 It sets forth general procedures that should be followed
Chloride-Containing Aqueous Environments
in conducting seawater exposure tests so that meaningful
comparisons may be made from one location to another, as
3. Significance and Use
described, for example, in (2, 3).
3.1 The procedures described herein are recommended for
1.3 This practice identifies recommended procedures for
evaluating the corrosion or marine fouling behavior, or both, of
evaluating the effects of natural surface seawater on the
materials exposed to quiescent or local tidal flow conditions, or
materials exposed.
both.
NOTE 1—Terms relative to this subject matter can be found in Termi-
3.1.1 This practice is not intended to cover the influence of
nology G 15.
high seawater velocity or the behavior of materials in seawater
1.4 This standard does not purport to address all of the
which has been transported from its source.
safety concerns, if any, associated with its use. It is the
3.1.2 Some aspects of this practice may be applicable to
responsibility of the user of this standard to establish appro-
testing in tanks and troughs which are continuously provided
priate safety and health practices and determine the applica-
with fresh surface seawater. Additionally, some aspects may
bility of regulatory limitations prior to use.
also be applicable to deep ocean testing.
NOTE 2—Guide G 78 provides guidance for conducting crevice corro-
2. Referenced Documents
sion tests under controlled seawater test conditions.
2.1 ASTM Standards:
3.2 While the duration of testing may be dictated by the test
D 3623 Test Method for Testing Anti-fouling Panels in
2 objectives, exposures of more than six months or one year are
Shallow Submergence
commonly used to minimize the effects of environmental
G 1 Practice for Preparing, Cleaning, and Evaluating Cor-
3 variables associated with seasonal changes or geographic
rosion Test Specimens
location, or both.
G 15 Terminology Relating to Corrosion and Corrosion
3 3.3 The procedures described are applicable for the expo-
Testing
sure of simple test panels, welded test panels, or those
G 30 Practice for Making and Using U-Bend Stress-
configured to assess the effects of crevices, or both, such as
Corrosion Test Specimens
those described in Guide G 78. In addition, they are useful for
G 38 Practice for Making and Using C-Ring Stress-
testing of actual components and fabricated assemblies.
Corrosion Test Specimens
3.4 It is prudent to include control materials with known
resistance to seawater corrosion or fouling, or both, as de-
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion
scribed in Test Method D 3623.
of Metals, and is the direct responsibility of Subcommittee G01.09on Corrosion in
NOTE 3—Materials which have been included in ASTM Worldwide
Natural Waters.
Current edition approved May 10, 2000. Published June 2000. Originally Seawater Corrosivity Studies include UNS K01501 (carbon steel), UNS
published as G 52 – 76. Last previous edition G 52 – 88 (1993).
C70600 (90/10 CuNi) and UNS A95086 (5086-H116 Al) (2, 3).
Annual Book of ASTM Standards, Vol 06.02.
Annual Book of ASTM Standards, Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G52
NOTE 4—In the case of evaluations of aluminum alloys, care should be
5.5.1 For multiple year exposures, it is recommended that
exercised in the location of specimens near copper or high copper-
the rack support rope be resistant to degradation by seawater as
containing alloys. In some instances, it is not sufficient to simply
well as ultraviolet light.
electrically isolate specimens to prevent bi-metallic (galvanic) corrosion;
5.6 Exposure racks should be suspended so that attached
copper ions from nearby corroding copper or copper-base alloys can
specimens will be oriented vertically and subjected to the full
deposit on aluminum and accelerate its corrosion.
effects of the seawater but free of galvanic contact with other
4. Test Sites
specimens and with minimal sedimentation of silt and debris
on the specimen.
4.1 Test sites should be chosen at locations representative of
natural seawater environments where the metals or alloys to be 5.6.1 It should be recognized that in time some support
tested may be used. Ideally, a natural seawater test site should ropes may stretch due to the added mass of marine fouling. In
have clean, uncontaminated seawater, be in a protected loca- shallow waters, this should be taken into account to avoid
tion, and have facilities for such tests as splash, tidal, and full unwanted contact with the sea bed or bottom. In some cases,
immersion. Reference should be made to tropical versus other the added mass will also make test rack removal more difficult.
conditions, and seasonal variations in temperature and in
NOTE 6—It should be recognized that barnacles attached to rack
deposition of marine growth on the test panels with a defined
support ropes will create potential hazards if manual lifting is required.
“fouling season.”
5.7 If periodic removals are envisioned, it is recommended
4.2 Periodic observations of critical water parameters
that different racks be utilized to support specimens for each
should be made and reported; depending on the experiment,
test period. Otherwise, marine fouling and corrosion products
these might include water temperature, salinity, conductivity,
on other specimens may be disturbed and possibly affect
pH, oxygen content, and tidal flow (velocity). If there is
subsequent behavior of the test material.
concern about the quality of water at the test site, it is
suggested that ammonia, hydrogen sulfide, and carbon dioxide 5.7.1 It is prudent to check the security of support ropes and
be determined periodically using analytical chemistry proce- the presence of the test racks from time-to-time.
dures.
6. Specimens
5. Exposure Racks
6.1 When the material to be tested is in sheet form, a
5.1 Test racks should be constructed of a material that will
nominal specimen size of 100 by 300 mm (approximately 4 by
remain intact for the entire proposed period of exposure.
12 in.) is recommended. Specimens may be larger or smaller to
Nickel-copper alloy 400 (UNS No. N04400) has been found to
suit a particular test.
be an excellent material, but is not recommended for holding
6.2 Odd shaped samples and assemblies comprising like or
aluminum specimens. Coated aluminum racks (6061-T6 or
dissimilar metals can also be tested. If testing materials in odd
5086-H32) also have given satisfactory service. Nonmetallic
shapes (bolts, nuts, pipes, etc.) is desired, a means of support-
racks made from reinforced plastic or treated wood might also
ing them in the test racks must be devised. It is important that
be used.
the specimens be electrically insulated from their respective
5.2 Specimens must be insulated from the test racks.
supports and from each other to prevent formation of galvanic
Mounting devices made of porcelain and other non-metallic
corrosion cells. In some instances it is not sufficient to isolate
materials are commonly used. It should be recognized that the
specimenselectricallytopreventcorrosionofonematerial.For
specimen contact areas with mounting devices may produce
example, great care must be exercised with aluminum speci-
crevice corrosion of some susceptible materials, for example,
mens or racks so that they will not be contaminated by copper,
some stainless steel and aluminum alloys.
which will cause accelerated corrosion of the aluminum. A
NOTE 5—Bolts used to secure the insulators must be galvanically galvanic couple is not necessary to accelerate the corrosion of
compatible with the test rack.
aluminum by copper. Copper or alloys containing copper
physically located in the vicinity of aluminum may corrode
5.3 Spacing of the mounted specimens can be important. It
sufficiently so that accelerated corrosion of the aluminum may
is desirable to have sufficient space between surfaces of test
becausedbycopperdepositiononthealuminum.(SeeNote4.)
specimens to ensure that adequate water flows between them
Again, appropriate insulating supports are required.
and that with long exposures the accumulated fouling will not
6.2.1 Some specimen configurations for evaluating resis-
block off the surface to the presence of the seawater environ-
tance to crevice corrosion or stress corrosion cracking may be
ment.
tested under this practice. Examples are provided in Guide
5.4 Specimen location maps or charts should be prepared
G 78, Practices G 30, G 38, G 39, and G 58.
and maintained to ensure positive identification at the conclu-
s
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