ASTM G161-00
(Guide)Standard Guide for Corrosion-Related Failure Analysis
Standard Guide for Corrosion-Related Failure Analysis
SCOPE
1.1 This guide covers key issues to be considered when examining metallic failures when corrosion is suspected as either a major or minor causative factor.
1.2 Corrosion-related failures could include one or more of the following: change in surface appearance (for example, tarnish, rust, color change), pin hole leak, catastrophic structural failure (for example, collapse, explosive rupture, implosive rupture, cracking), weld failure, loss of electrical continuity, and loss of functionality (for example, seizure, galling, spalling, swelling).
1.4 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.
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Designation:G161–00
Standard Guide for
Corrosion-Related Failure Analysis
This standard is issued under the fixed designation G 161; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Significance and Use
1.1 This guide covers key issues to be considered when 3.1 This guide is intended to assist those encountering
examining metallic failures when corrosion is suspected as corrosion or possible corrosion as a causative factor in a failure
either a major or minor causative factor. analysis.
1.2 Corrosion-related failures could include one or more of 3.2 This guide is not an absolute plan that will identify the
the following: change in surface appearance (for example, cause of corrosion in all failure analyses.
tarnish, rust, color change), pin hole leak, catastrophic struc- 3.3 This guide is intended to help an investigator identify
tural failure (for example, collapse, explosive rupture, implo- significant sources and types of corrosion information that may
sive rupture, cracking), weld failure, loss of electrical continu- be available for failure analysis.
ity, and loss of functionality (for example, seizure, galling, 3.4 Appendix X1 contains a checklist that is intended to
spalling, swelling). assist in corrosion-related failure evaluations.
1.3 Issues covered include overall failure site conditions,
4. Organizing the Analysis
operatingconditionsatthetimeoffailure,historyofequipment
and its operation, corrosion product sampling, environmental 4.1 Early recognition of corrosion as a factor in a failure
analysis is critical to any such investigation. Therefore, it is
sampling, metallurgical and electrochemical factors, morphol-
ogy (mode) or failure, and by considering the preceding, generally desirable to conduct the analysis as soon as possible
after the apparent failure. It is always desirable to protect the
deducing the cause(s) of corrosion failure.
1.4 This standard does not purport to address all of the physical evidence until the analysis can begin. Much important
corrosion information can be lost if a failure scene is altered or
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- changed before appropriate observations can be made.
4.2 A written plan for the detailed analysis should be
priate safety and health practices and determine the applica-
prepared. The plan may include methods of documentation
bility of regulatory limitations prior to use.
(photographs before and during analysis, sketches, statements),
2. Referenced Documents
responsibilities of parties, reporting needs, and scheduling.
2.1 ASTM Standards: 4.3 If the capability (corrosion knowledge and experience)
E 3 Methods of Preparation of Metallographic Specimens of in-house personnel and availability of resources are inad-
E 1459 Guide for Physical Evidence Labeling and Related equate to make the analysis in a timely manner, it may be
Documentation expedient to seek third party services.
E 1492 Practice for Receiving, Documenting, Storing, and
3 5. Failure Site Conditions
Retrieving Evidence in a Forensic Science Laboratory
5.1 When possible, an overall examination of the conditions
G 1 Practice for Preparing, Cleaning, and Evaluating Cor-
rosion Test Specimens at a failure site prior to cleaning, moving, or sampling debris
should be conducted. Impressions as to physical arrangements,
G 46 Guide for Examination and Evaluation of Pitting
Corrosion odors, colors, textures, and conditions of adjacent structures
can provide important clues as to active corrosion processes.
5.2 Photographs or videotapes serve as documentation of
This guide is under the jurisdiction ofASTM Committee G01 on Corrosion of
theobservations.Colorphotographsarepreferable.Itishelpful
Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
to include labels and indications of size, location, and orienta-
Corrosion Tests.
tion in the photographs. Photographs before, during, and after
Current edition approved May 10, 2000. Published June 2000. Originally
published as G 161- 99. Last previous edition G 161 - 99a.
sampling are recommended.
Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 14.02.
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.
G161
5.3 Sketches and drawings with notes as to detailed obser- naloperatingparameters,andanomalousoperatingparameters,
vations can be beneficial for later evaluations. Locations of including out-of-specification periods and significant down-
samples and photographs may be shown.
time periods.
5.4 Interviews with those who were present or nearby when
7.5 Maintenance, cleaning, and repair histories may be
thefailureoccurredwouldbeappropriate.Informationontime,
important and should be documented.
sights, sounds, and conditions can be gained during such
7.6 Changesinspecificationfor,andsourcesof,processraw
interviews.
materials and supplies may be significant and should be
evaluated.
6. Operating Conditions At Time of Failure
6.1 Ascertain the operating conditions from operator’s logs,
8. Sampling
recorders, and data loggers (verify the accuracy of time
8.1 Careful sampling is critical to the successful investiga-
records). Special attention should be given to the stability of
tion of corrosion-related failures. Sampling in corrosion inves-
the operating conditions, for example, were they stable or
tigations is similar to that used in forensic investigations by
variable. Conditions of corrosion concern could be tempera-
criminologists. Guide E 1459 and Practice E 1492 address
ture, pressure, flow rate, velocity, process stream pH and
issues of labeling and documenting field evidence. These
chemical composition, time, and weather.
standards may provide useful guidance during sampling for
6.2 Special attention should be given to out-of-specification
corrosion investigations.
or other abnormal or unusual upset conditions.
6.3 It may be necessary to plot or track operating conditions 8.2 The written plan suggested in 4.2 should be supple-
mented with a written sampling plan. The plan should specify
for an indefinite period of time prior to the detection of failure
to more clearly identify any unusual, contributory operating a sample location, identification system, and method of collec-
conditions. tion.
6.4 If similar, parallel equipment at the same or other
8.3 Avoid contamination during sampling by using clean
location was operating at the time of the corrosion-related
tools. Personnel should wear gloves to avoid fingerprints and
failure, note the operating conditions as a reference point. Such
personal contact.
information could be useful in judging the normalcy of the
8.4 Sample containers should be clean and sealable to
operating conditions associated with the failure.
protect samples from contamination and damage. The material
6.5 Corrosion monitoring instruments and coupons, if
of sample containers should be selected carefully to avoid
present, should be examined to help document operating
undesirable interaction with samples. Each container should be
conditions at the time of failure.
dated and identified according to the sampling plan.
8.5 Samples of corroded and uncorroded materials may be
7. Historical Information
useful in the identification of causative factors. Samples should
7.1 Historical information, when available, is extremely
be as large as practical to give analysts sufficient material to
useful in understanding some situations. All of the types of
work with and to protect critical corroded areas from damage
information noted may not be useful. Often in cases of older
during cutting and transporting. If failure initiation location is
equipment, historical information may be nearly impossible to
apparent, it should be sampled. When cutting samples, consid-
find because of lost files or retired personnel. Based on cost,
eration should be given to temperature control and to the
time, and anticipated benefit, a judgement must be made as to
introduction of cutting and cooling fluids that could alter the
the effort one should expend in retrieving historical informa-
surface and metallurgical conditions. Because of the solubility
tion.
in water of many corrosion products, samples must be pro-
7.2 Useful details regarding original constructions may
tected from extraneous moisture.
include, but are not limited to, design drawings and specifica-
8.6 Corrosion products and deposits should be given special
tions, material specifications (composition, thermal treatments,
sampling treatment because they are often key elements in
surface treatments), joining (bolts, rivets, welds, adhesives),
understanding the failure. Care should be used in the selection
and surface treatments (coatings, pickling, etching, anodizing,
of tools for collecting these samples. Nonmetallic tools are
plating, peening, grinding, insulation, or refractories).
often preferred because they present less chance for contami-
7.3 Details regarding modifications made subsequent to
nationofthesampleorfordamagingcriticalcorrodedsurfaces.
original fabrication and prior to the corrosion-related failure
When there is insufficient corrosion product or deposit for easy
may be extremely important because they often reveal less-
field sampling, care should be used when handling material so
than-optimum field work. Modifications may have been made
that subsequent laboratory sampling may be conducted. Be-
foroneormorereasons,including,butnotlimitedto,problems
cause of the solubility in water of many corrosion products,
with original design, changed service requirements, corrected
samples must be protected from extraneous moisture.
earlier failures, and correction of safety and environmental
8.7 Process stream samples may be desirable. The most
concerns. The same types of details suggested in 7.2 should be
considered regarding modifications. useful process stream samples are those taken from the failure
7.4 Details regarding operating history may be important. location as soon after the event as possible. Delayed or typical
process stream samples ar
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