ASTM G161-00(2006)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: G161 − 00(Reapproved 2006)
Standard Guide for
Corrosion-Related Failure Analysis
This standard is issued under the fixed designation G161; 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 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
be available for failure analysis.
continuity, and loss of functionality (for example, seizure,
galling, spalling, swelling).
3.4 Appendix X1 contains a checklist that is intended to
assist in corrosion-related failure evaluations.
1.3 Issues covered include overall failure site conditions,
operatingconditionsatthetimeoffailure,historyofequipment
4. Organizing the Analysis
and its operation, corrosion product sampling, environmental
sampling, metallurgical and electrochemical factors, morphol-
4.1 Early recognition of corrosion as a factor in a failure
ogy (mode) or failure, and by considering the preceding,
analysis is critical to any such investigation. Therefore, it is
deducing the cause(s) of corrosion failure.
generally desirable to conduct the analysis as soon as possible
1.4 This standard does not purport to address all of the
after the apparent failure. It is always desirable to protect the
safety concerns, if any, associated with its use. It is the physical evidence until the analysis can begin. Much important
responsibility of the user of this standard to establish appro-
corrosion information can be lost if a failure scene is altered or
priate safety and health practices and determine the applica- changed before appropriate observations can be made.
bility of regulatory limitations prior to use.
4.2 A written plan for the detailed analysis should be
2. Referenced Documents prepared. The plan may include methods of documentation
2 (photographsbeforeandduringanalysis,sketches,statements),
2.1 ASTM Standards:
responsibilities of parties, reporting needs, and scheduling.
E3 Guide for Preparation of Metallographic Specimens
E1459 Guide for Physical Evidence Labeling and Related
4.3 If the capability (corrosion knowledge and experience)
Documentation
of in-house personnel and availability of resources are inad-
E1492 Practice for Receiving, Documenting, Storing, and
equate to make the analysis in a timely manner, it may be
Retrieving Evidence in a Forensic Science Laboratory
expedient to seek third party services.
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
sion Test Specimens
5. Failure Site Conditions
G46 Guide for Examination and Evaluation of Pitting Cor-
5.1 When possible, an overall examination of the conditions
rosion
at a failure site prior to cleaning, moving, or sampling debris
should be conducted. Impressions as to physical arrangements,
This guide is under the jurisdiction ofASTM Committee G01 on Corrosion of
odors, colors, textures, and conditions of adjacent structures
Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
Corrosion Tests. can provide important clues as to active corrosion processes.
Current edition approved Nov. 1, 2006. Published January 2007. Originally
5.2 Photographs or videotapes serve as documentation of
approved in 1999. Last previous edition approved in 2000 as G161 – 00. DOI:
10.1520/G0161-00R06.
theobservations.Colorphotographsarepreferable.Itishelpful
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
to include labels and indications of size, location, and orienta-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
tion in the photographs. Photographs before, during, and after
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. sampling are recommended.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G161 − 00 (2006)
5.3 Sketches and drawings with notes as to detailed obser- 7.4 Details regarding operating history may be important.
vations can be beneficial for later evaluations. Locations of Three types of operating information that may require docu-
samples and photographs may be shown. mentation are original design parameters, chronology of nomi-
naloperatingparameters,andanomalousoperatingparameters,
5.4 Interviews with those who were present or nearby when
including out-of-specification periods and significant down-
thefailureoccurredwouldbeappropriate.Informationontime,
time periods.
sights, sounds, and conditions can be gained during such
7.5 Maintenance, cleaning, and repair histories may be
interviews.
important and should be documented.
6. Operating Conditions At Time of Failure
7.6 Changesinspecificationfor,andsourcesof,processraw
materials and supplies may be significant and should be
6.1 Ascertain the operating conditions from operator’s logs,
evaluated.
recorders, and data loggers (verify the accuracy of time
records). Special attention should be given to the stability of
8. Sampling
the operating conditions, for example, were they stable or
8.1 Careful sampling is critical to the successful investiga-
variable. Conditions of corrosion concern could be tempera-
tion of corrosion-related failures. Sampling in corrosion inves-
ture, pressure, flow rate, velocity, process stream pH and
tigations is similar to that used in forensic investigations by
chemical composition, time, and weather.
criminologists. Guide E1459 and Practice E1492 address
6.2 Special attention should be given to out-of-specification
issues of labeling and documenting field evidence. These
or other abnormal or unusual upset conditions.
standards may provide useful guidance during sampling for
6.3 It may be necessary to plot or track operating conditions
corrosion investigations.
for an indefinite period of time prior to the detection of failure
8.2 The written plan suggested in 4.2 should be supple-
to more clearly identify any unusual, contributory operating
mented with a written sampling plan. The plan should specify
conditions.
a sample location, identification system, and method of collec-
6.4 If similar, parallel equipment at the same or other tion.
location was operating at the time of the corrosion-related
8.3 Avoid contamination during sampling by using clean
failure, note the operating conditions as a reference point. Such
tools. Personnel should wear gloves to avoid fingerprints and
information could be useful in judging the normalcy of the
personal contact.
operating conditions associated with the failure.
8.4 Sample containers should be clean and sealable to
6.5 Corrosion monitoring instruments and coupons, if
protect samples from contamination and damage. The material
present, should be examined to help document operating
of sample containers should be selected carefully to avoid
conditions at the time of failure.
undesirable interaction with samples. Each container should be
dated and identified according to the sampling plan.
7. Historical Information
8.5 Samples of corroded and uncorroded materials may be
7.1 Historical information, when available, is extremely
useful in the identification of causative factors. Samples should
useful in understanding some situations. All of the types of
be as large as practical to give analysts sufficient material to
information noted may not be useful. Often in cases of older
work with and to protect critical corroded areas from damage
equipment, historical information may be nearly impossible to
during cutting and transporting. If failure initiation location is
find because of lost files or retired personnel. Based on cost,
apparent, it should be sampled. When cutting samples, consid-
time, and anticipated benefit, a judgement must be made as to
eration should be given to temperature control and to the
the effort one should expend in retrieving historical informa-
introduction of cutting and cooling fluids that could alter the
tion.
surface and metallurgical conditions. Because of the solubility
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-
tions, material specifications (composition, thermal treatments, 8.6 Corrosion products and deposits should be given special
surface treatments), joining (bolts, rivets, welds, adhesives),
sampling treatment because they are often key elements in
and surface treatments (coatings, pickling, etching, anodizing,
understanding the failure. Care should be used in the selection
plating, peening, grinding, insulation, or refractories).
of tools for collecting these samples. Nonmetallic tools are
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
concerns. The same types of details suggested in 7.2 should be 8.7 Process stream samples may be desirable. The most
considered regarding modifications. useful process stream s
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