ASTM G146-01(2007)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:G146 −01(Reapproved 2007)
Standard Practice for
Evaluation of Disbonding of Bimetallic Stainless Alloy/Steel
Plate for Use in High-Pressure, High-Temperature Refinery
Hydrogen Service
This standard is issued under the fixed designation G146; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope and the effects of test conditions, materials, and welding
variables, and inspection techniques is given in Appendix X1.
1.1 This practice covers a procedure for the evaluation of
disbonding of bimetallic stainless alloy/steel plate for use in 1.5 The values stated in SI units are to be regarded as
refinery high-pressure/high-temperature (HP/HT) gaseous hy- standard. No other units of measurement are included in this
drogen service. It includes procedures to (1) produce suitable standard.
laboratory test specimens, (2) obtain hydrogen charging con-
1.6 This standard does not purport to address all of the
ditions in the laboratory that are similar to those found in
safety concerns, if any, associated with its use. It is the
refinery HP/HT hydrogen gas service for evaluation of bime-
responsibility of the user of this standard to establish appro-
tallic specimens exposed to these environments, and (3)
priate safety and health practices and determine the applica-
perform analysis of the test data. The purpose of this practice
bility of regulatory limitations prior to use. See Section 6 for
is to allow for comparison of data among test laboratories on
additional safety information.
the resistance of bimetallic stainless alloy/steels to hydrogen-
induced disbonding (HID).
2. Referenced Documents
1.2 This practice applies primarily to bimetallic products
2.1 ASTM Standards:
fabricated by weld overlay of stainless alloy onto a steel
G111Guide for Corrosion Tests in High Temperature or
substrate. Most of the information developed using this prac-
High Pressure Environment, or Both
tice has been obtained for such materials. The procedures
E3Guide for Preparation of Metallographic Specimens
described herein, may also be appropriate for evaluation of hot
2.2 ASME Standard:
roll bonded, explosive bonded, or other suitable processes for
Boiler and Pressure Vessel Code Section V,Article 5,Tech-
applying stainless alloys on steel substrates. However, due to
nique Two
the broad range of possible materials, test conditions, and
variationsintestprocedures,itisuptotheuserofthispractice
3. Terminology
to determine the suitability and applicability of these proce-
3.1 Definitions:
dures for evaluation of such materials.
3.1.1 HID—a delamination of a stainless alloy surface layer
1.3 This practice is intended to be applicable for evaluation
fromitssteelsubstrateproducedbyexposureofthematerialto
of materials for service conditions involving severe hydrogen
a hydrogen environment.
charging which may produce HID as shown in Fig. 1 for
3.1.1.1 Discussion—This phenomenon can occur in inter-
stainlesssteelweldoverlayonsteelequipment(seeRefs1and
nally stainless alloy lined steel equipment by the accumulation
2in Appendix X1). However, it should be noted that this
of molecular hydrogen in the region of the metallurgical bond
practice may not be appropriate for forms of bimetallic
at the interface between the steel and stainless alloy surface
construction or service conditions which have not been ob-
layer produced by exposure to service conditions involving
served to cause HID in service.
HP/HT hydrogen in the refinery hydroprocessing.
1.4 Additional information regarding the evaluation of bi-
metallicstainlessalloy/steelplateforHID,testmethodologies,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction ofASTM Committee G01 on Corrosion contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory Standards volume information, refer to the standard’s Document Summary page on
Corrosion Tests. the ASTM website.
Current edition approved May 1, 2007. Published May 2007. Originally Available from American Society of Mechanical Engineers (ASME), ASME
approvedin1996.Lastpreviouseditionin2001asG146–01.DOI:10.1520/G0146- International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
01R07. www.asme.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G146−01 (2007)
the resistance to decarburization, internal blistering or
cracking, or both, to be evaluated.
6. Apparatus
6.1 Becausethispracticeisintendedtobeconductedathigh
pressures and high temperatures, the apparatus must be con-
structed to safely contain the test environment while being
resistant to the cumulative embrittling effects of hydrogen.
Secondly, the test apparatus must be capable of allowing (1)
introductionofthetestgas,(2)removalofairfromthetestcell,
(3) uniform heating of the test specimens, and (4) cooling of
the specimens at controlled rates.
6.2 There are many types of test cell configurations which
can be used to conduct evaluations of HID. This practice does
not recommend or endorse any particular test cell design. Fig.
NOTE 1—Open symbols—no disbonding reported. Filled symbols—
disbonding reported.
2 shows a schematic representation of a typical test cell
FIG. 1Conditions of Hydrogen Partial Pressure and Temperature
designed to conduct HID tests in HP/HT gaseous hydrogen
with Demonstrated Susceptibility to Hydrogen Disbonding in Re-
environments. Other designs may also provide acceptable
finery High-Pressure Hydrogen Service
performance. However, the typical components should include
the following:
6.2.1 Metal Test Cell—The test cell should be constructed
4. Summary of Practice
frommaterialswhichhavebeenproventohavehighresistance
to hydrogen embrittlement and high-temperature hydrogen
4.1 Stainlessalloy/steelspecimensareexposedtoagaseous
hydrogen containing environment at HP/HT conditions for attackundertheanticipatedtestconditions.Materialswithlow
resistance to these phenomena should be avoided. Typical test
sufficient time to produce hydrogen charging in the material.
Following exposure, the specimens are cooled to ambient cells for high-pressure hydrogen testing are constructed from
stainless steel (UNS S31600 or S34700) or nickel alloys (UNS
temperatureatacontrolledrate.Thespecimensarethenheldat
room temperature for a designated period to allow for the N10276 or N06625) in the solution annealed condition. Steel
vessels with stainless alloy exposed surfaces may also be
development of HID between the stainless alloy surface layer
and the steel. Following the hold period, the specimens are suitable.
evaluated for HID at this interface using straight beam ultra-
sonicmethodswithmetallographicexaminationtoconfirmany
HID found. The size and distribution of the disbonded re-
gion(s) are then characterized by this practice. Single or
multiple hydrogen exposure/cooling cycles can be conducted
and varying exposure conditions and cooling rates can be
incorporated into this evaluation to provide assessment of the
disbonding characteristics of materials and service condition
used for refinery process equipment containing HP/HT hydro-
gen containing environments.
5. Significance and Use
5.1 This practice provides an indication of the resistance or
susceptibility, or both, to HID of a metallurgically bonded
stainlessalloysurfacelayeronasteelsubstrateduetoexposure
to hydrogen-containing gaseous environments under HP/HT
conditions. This practice is applicable over a broad range of
pressures, temperatures, cooling rates, and gaseous hydrogen
environmentswhereHIDcouldbeasignificantproblem.These
procedures can be used to assess the effects of material
composition, processing methods, fabrication techniques, and
heat treatment as well as the effects of hydrogen partial
pressure, service temperature, and cooling rate. The HID
produced by these procedures may not correlate directly with
serviceexperienceforparticularapplications.Additionally,this
practice does not address the evaluation of high-temperature
hydrogen attack in the steel substrate. Typically, longer expo-
sure times at the test conditions must be utilized to allow for FIG. 2 Typical Test Cell
G146−01 (2007)
6.2.2 Closure and Seal—To facilitate operation of the test constantwhilethespecimensareinthehigh-pressurehydrogen
cell, the closure should provide for rapid opening and closing environment. Once the temperature of the specimens reaches
of the test cell while retaining reliable sealing capabilities for 200°C, the hydrogen gas environment may be removed and
hydrogen. This can include either metallic or nonmetallic replaced with inert gas followed by opening of the test vessel
materials with high resistance to thermal degradation and toair.Subsequentcoolingfrom200°Cshallbeconductedsuch
hydrogen attack. thatthespecimensarecooledtoambienttemperaturebyforced
6.2.3 Gas Port(s)—The gas port should be designed to air of 30 to 60 m/min around all sides of the specimens while
promoteflowandcirculationofthegaseoustestenvironments, they are supported on ceramic blocks or spacers. If linear
inert gas purging, and evacuation as required to produce the cooling can not be obtained in this range with forced air,
intended test environment. Usually two ports are used so that specimens may be misted with water to provide additional
separate flow-through capabilities are attained to facilitate control.
these functions.
8.3 If simulation of actual conditions is required, these
6.2.4 Electrical Feed-Throughs—High-temperature condi-
conditions may be modified to better represent the intended
tions are required in this practice. It is usually advantageous to
refinery service conditions of interest. However, these condi-
utilize an internal heater to heat just the test specimens and the
tions must be reported. See Section 13.
gaseous environment in the immediate vicinity of the speci-
men. Therefore, feed-throughs are usually needed to make
9. Sampling
electrical contact with an internal resistance or induction
9.1 The procedure for sampling stainless alloy bimetallic
heater. These feed-throughs must also provide (1) electrical
products should be sufficient to provide specimens that are
isolation from the test cell and internal fixtures and (2)
representative of the plate from which they are taken. The
maintain a seal to prevent leakage of the test environment. If
details of this procedure should be covered in product or
external heaters are used, no electric feed-throughs are re-
purchase specifications and are not covered in this practice.
quired.
9.2 Sampling of the test environment is recommended to
6.2.5 Electric Resistance or Induction Heater(s)—Either
confirm that the test procedure is in conformance with this
internal or external heaters can be used to obtain elevated
practiceandattainstheintendedtestconditions.Thefrequency
temperature. For lower temperatures (<300°C), external heat-
of environmental sampling should be covered in applicable
ing of the test cell is typically more convenient but may limit
product, purchase, or testing specifications, or both. As a
cooling rates since they heat the entire vessel. For high
minimum requirement to be in compliance with this practice,
temperatures(>300°C),aninternalheateriscommonlyusedto
samplingofthetestenvironmentshallbeconductedatthestart
heatonlythetestspecimenandthegaseousenvironmentinthe
oftestinginaparticularapparatusandwhenanyelementofthe
vicinity of the test specimens to limit power requirements and
test procedure or test system has been changed or modified.
problems with high-temperature sealing and pressure contain-
ment.
10. Test Specimens
7. Reagents 10.1 The standard test specimen is shown in Fig. 3.It
consists of a cylindrical section machined from a stainless
7.1 Purity of Reagents—Low oxygen gases (<1 ppm) shall
alloy/steel plate sample fabricated with methods to be used in
be used in all tests.
the actual equipment fabrication under consideration. The
8. Test Conditions
8.1 Thetestenvironmentisbasedonattainingconditionsof
high-pressure hydrogen gas. The test temperature and hydro-
gen gas pressure are selected to simulate those conditions
found in refinery hydrogen-containing environments. These
typically range from 14 to 20 MPa hydrogen gas pressure and
temperature from 300 to 500°C depending on actual refinery
service conditions under consideration, but may be selected
over the range of conditions in Fig. 1 that have been shown to
produce HID.
8.2 One of the major variables involved in testing for HID
of stainless alloy/steel plate is the cooling rate selected for
evaluation.Coolingratesashighas260°C/hhavebeenutilized
to intentionally produce disbonding for the purposes of inves-
tigating hydrogen disbonding mechanisms. The cooling rate
adopted most readily for qualification testing is 150°C/h.
Slower cooling rates can be utilized for the purposes of
simulating the effects of particular shutdown conditions expe-
rienced in refinery equipment. The cooling rate from the test
temperature to 200°C shall be controlled and maintained FIG. 3 Test Specimen Configuration
G146−01 (2007)
dimensions of the specimen shall be 73 6 2 mm in diameter
and 45 6 2 mm thick. However, for thinner cross-section
materials, the thickness of the specimen may be reduced to
match the plate thickness being evaluated.
10.2 The thickness of the stainless alloy surface layer to be
evaluatedshallbenominallythesameasthatbeingusedinthe
process to be evaluated.
10.3 A stainless alloy overlay weld shall be applied to the
sides of the specimen to promote through-thickness diffusion
of hydrogen following exposure. If the bimetallic plate has not
already been heat treated following fabrication, the entire
specimenshallbeheattreatedforthetimeandtemperatureand
withasimilarcoolingratefromtheheat-treatmenttemperature
normally required for the bimetallic product. However, if the
bimetallic plate sample has already been heat treated, the side
overlay weld shall be heat treated at a temperature of 600°C
maximum, with a similar cooling rate used for the bimetallic
product prior to testing.
10.4 The only steel surface on the specimen is the one
opposite the alloy surface being evaluated in the test. The
purpose of the side overlay is to limit diffusion of hydrogen in
the radial direction during and after cooling of the specimen
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