ASTM D807-00
(Practice)Standard Practice for Assessing the Tendency of Industrial Boiler Waters to Cause Embrittlement (USBM Embrittlement Detector Method)
Standard Practice for Assessing the Tendency of Industrial Boiler Waters to Cause Embrittlement (USBM Embrittlement Detector Method)
SCOPE
1.1 This practice, known as the embrittlement-detector method, covers the apparatus and procedure for determining the embrittling or nonembrittling characteristics of the water in an operating boiler. The interpretation of the results shall be restricted to the limits set forth in Section 12.
Note 1--The embrittlement detector was designed to reproduce closely the conditions existing in an actual boiler seam. It is considered probable that the individual conditions of leakage, concentration, and stress in the boiler seam can equal those in the detector. The essential difference between the detector and the boiler is that the former is so constructed and operated that these three major factors act simultaneously, continuously, and under the most favorable circumstances to produce cracking; whereas, in the boiler the three factors are brought together only under unique circumstances. Furthermore, in the detector any cracking is produced in a small test surface that can be inspected thoroughly, while the susceptible areas in a boiler are large and can be inspected only with difficulty. In these respects the embrittlement detector provides an accelerated test of the fourth condition necessary for embrittlement, the embrittling nature of the boiler water.
Note 2--Cracks in a specimen after being subjected to this test indicate that the boiler water can cause embrittlement cracking, but not that the boiler in question necessarily has cracked or will crack.
1.2 The effectiveness of treatment to prevent cracking, as well as an indication of whether an unsafe condition exists, are shown by this practice. Such treatments are evaluated in terms of method specimen resistance to failure.
1.3 The practice may be applied to embrittlement resistance testing of steels other than boiler plate, provided that a duplicate, unexposed specimen does not crack when bent 90o on a 2-in. (51-mm) radius.
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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An American National Standard
Designation:D 807–00
Standard Practice for
Assessing the Tendency of Industrial Boiler Waters to
Cause Embrittlement (USBM Embrittlement Detector
Method)
This standard is issued under the fixed designation D 807; 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 1.2 The effectiveness of treatment to prevent cracking, as
3 well as an indication of whether an unsafe condition exists, are
1.1 This practice, known as the embrittlement-detector
shown by this practice. Such treatments are evaluated in terms
method, covers the apparatus and procedure for determining
of method specimen resistance to failure.
the embrittling or nonembrittling characteristics of the water in
1.3 The practice may be applied to embrittlement resistance
an operating boiler. The interpretation of the results shall be
testing of steels other than boiler plate, provided that a
restricted to the limits set forth in Section 12.
duplicate, unexposed specimen does not crack when bent 90°
NOTE 1—Theembrittlementdetectorwasdesignedtoreproduceclosely
on a 2-in. (51-mm) radius.
the conditions existing in an actual boiler seam. It is considered probable
1.4 This standard does not purport to address all of the
that the individual conditions of leakage, concentration, and stress in the
safety concerns, if any, associated with its use. It is the
boiler seam can equal those in the detector. The essential difference
responsibility of the user of this standard to establish appro-
between the detector and the boiler is that the former is so constructed and
priate safety and health practices and determine the applica-
operated that these three major factors act simultaneously, continuously,
andunderthemostfavorablecircumstancestoproducecracking;whereas,
bility of regulatory limitations prior to use.
in the boiler the three factors are brought together only under unique
circumstances. Furthermore, in the detector any cracking is produced in a 2. Referenced Documents
small test surface that can be inspected thoroughly, while the susceptible
2.1 ASTM Standards:
areas in a boiler are large and can be inspected only with difficulty. In
A 108 Specification for Steel Bars, Carbon, Cold-Finished,
these respects the embrittlement detector provides an accelerated test of
Standard Quality
the fourth condition necessary for embrittlement, the embrittling nature of
the boiler water. A 515/A 515M Specification for Pressure Vessel Plates,
NOTE 2—Cracksinaspecimenafterbeingsubjectedtothistestindicate
Carbon Steel, for Intermediate- and Higher-Temperature
that the boiler water can cause embrittlement cracking, but not that the
Service
boiler in question necessarily has cracked or will crack.
D 1129 Terminology Relating to Water
E 3 Methods of Preparation of Metallographic Specimens
E 883 Guide for Reflected-Light Photomicrography
United States Bureau of Mines.
E 1351 Practice for Production and Evaluation of Field
This test method is under the jurisdiction ofASTM Committee D–19 on Water
Metallographic Replicas
and is the direct responsibility of Subcommittee D19.03 on Sampling of Water and
Water-Formed Deposits, Surveillamce of Water and Flow Measurement of Water.
Current edition approved June 10, 2000. Published September 2000. Originally 3. Terminology
published as D807 – 44 T. Last previous edition D807 – 96.
3.1 Definitions:
This test method was developed during an investigation conducted under a
3.1.1 The term embrittlement cracking in this test method is
cooperative agreement between the Joint Research Committee on Boiler Feedwater
Studies and the United States Bureau of Mines.
defined in accordance with Terminology D 1129 as follows:
For information on the development of this test method reference may be made
3.1.1.1 embrittlement cracking—aformofmetalfailurethat
to the following:
occurs in steam boilers at riveted joints and at tube ends, the
Schroeder, W. C. and Berk, A. A. “Intercrystalline Cracking of Boiler Steel and
Its Prevention,” Bulletin 443, U.S. Bureau of Mines, 1941. cracking being predominantly intercrystalline.
Schroeder, W. C., Berk, A. A. and Stoddard, C. K. “Embrittlement Detector
NOTE 3—This form of cracking, which has been known as “caustic
Testing on Boilers,” Power Plant Engineering, Vol 45, August, 1941, pp. 69–76.
embrittlement,”isbelievedtoresultfromtheactionofcertainconstituents
“Embrittlement Symposium,” Transactions of the Am. Soc. Mech. Engrs., Vol
64, 1942, pp. 393–444.
Whirl, S. F. and Purcell, T. E. “Protection Against Caustic Embrittlement by
Coordinated Phosphate-pH Control,” Proceedings,ThirdAnnualWater Conference, Annual Book of ASTM Standards, Vol 01.05.
Engrs. Soc. of Western Penna., 1942, pp. 45–60. Annual Book of ASTM Standards, Vol 01.04.
Berk, A. A. and Schroeder, W. C. “A Practical Way to Prevent Embrittlement Annual Book of ASTM Standards, Vol 11.01.
Cracking,” Transactions, Am. Soc. Mech. Engr., Vol 65, 1943, pp. 701–711. Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D807–00
of concentrated boiler water upon steel under stress.
NOTE 4—For a detailed discussion as to what cracking should be
considered significant for the purpose of this practice, see Section 12.
3.1.2 For definitions of other terms used in this practice,
refer to Terminology D 1129.
4. Summary of Practice
4.1 For embrittlement cracking of the boiler metal to be
possible, the boiler water must concentrate a thousand times or
more in contact with the metal under high residual or applied
tensile stress. In a boiler such concentration may take place in
riveted seams or in annular spaces at tube ends, and the steel at
such locations may be highly stressed when the boiler is
constructedormaybecomehighlystressedwhenitisoperated.
If the chemicals in the boiler water concentrate in the seams to
develop an embrittling solution, cracking may occur.
4.2 In the embrittlement detector (Fig. 1), the conditions of
FIG. 2 Embrittlement Detector Installed
concentration and stress are provided by the design of the unit.
Boiler water is permitted to seep slowly from the small hole
some waters is not well understood. Experience has shown that
through the restricted space between the contact surfaces of the
certain waters exhibit an embrittling characteristic while others
test specimen and the groove in the block. As this extremely
do not.
slow flow takes place toward atmospheric pressure, the heat in
5.2 Because embrittlement is a form of cracking, it is nearly
the metal and in the liquid causes progressive evaporation to
impossible to detect in an operating boiler until a failure has
produce an increasingly concentrated solution. When the
occured. In general, cracking failures tend to be sudden, and
detector is properly adjusted, concentrated boiler water is in
often with serious consequences. This practice offers a way to
contact with the stressed test surface of the specimen, thus
determine whether a particular water is embrittling or not. It
providing the necessary factor to determine whether the boiler
also makes it possible to determine if specific treatment actions
water can cause embrittlement cracking.
have rendered the water nonembrittling.
5. Significance and Use
6. Apparatus
5.1 Embrittlement is a form of intercrystalline cracking that
6.1 Embrittlement Detector—The embrittlement detector
is associated with the exposure of boiler steel to a combination
of physical and chemical factors. For embrittlement of boiler shall consist of the unit, complete with steel specimen, as
shown assembled in cross section in Fig. 1 and as the installed
metal to occur, the metal must be under stress, it must be at the
site of a leak, and it must be exposed to the concentrated boiler unit in Fig. 2.The principal parts consist of a rectangular block
base through which the water circulates and in which a groove
water. In addition, the boiler water must be embrittling in
nature.Theprecisechemicalcausesoftheembrittlingnatureof has been machined to receive the test specimen, a test
specimen, and a clamping plate which fits over four stud bolts
in the block. When the nuts on the stud bolts are tightened, the
pressure of the clamping plate molds the test specimen to the
contour of the groove, thus stressing in tension the surface of
the specimen. Working drawings (Note 4) showing the dimen-
sionsofallthemachinedpartsareshowninFigs.3-5.Accurate
machining of the groove with respect to the small hole through
which the boiler water is brought to the test surface of the
specimen is especially important.
6.2 Wrenches—An extra-heavy box-type wrench of 27-mm
(1 ⁄16-in.) opening is recommended for assembling and adjust-
ing the unit. A lighter box-type wrench of 19-mm ( ⁄4-in.)
opening is recommended for the hexagonal head of the
adjusting screw in the end of the specimen.
6.3 Jig for Bending Specimen—Ajig as shown in Fig. 6, or
its equivalent, is recommended for bending the specimen with
a hydraulic press at the end of the test to reveal cracks that may
have been formed but are too fine to be visible without
additional stressing of the steel surface. Other devices may be
substituted to effect the same purpose of bending the specimen
uniformly in the proper place without injuring the surface to be
FIG. 1 Cross-Section of Embrittlement Detector studied (Note 5). A vise and sledge hammer shall not be used.
D807–00
in. mm in. mm in. mm in. mm
1 11 3 1
⁄64 0.39 ⁄16 17.46 1 ⁄16 30 2 ⁄4 57
1 23 1 3
⁄8 3.17 ⁄32 18.25 1 ⁄4 31.7 2 ⁄8 60
3 3 11 1
⁄16 4.76 ⁄4 19 1 ⁄16 42.8 2 ⁄2 63.5
5 13 3 9
⁄16 7.93 ⁄16 20.63 1 ⁄4 44.4 2 ⁄16 65
3 7 13 1
⁄8 9.52 ⁄8 22.22 1 ⁄16 46 3 ⁄8 79
27 7 1
⁄64 10.71 1 25.4 1 ⁄8 47.6 3 ⁄2 89
1 1
⁄2 12.7 1 ⁄8 28.6 2 50.8 5 127
⁄8 15.87
FIG. 3 Dimensional Details of Base Block of Embrittlement Detector
in. mm in. mm
1 3
⁄8 3.17 ⁄8 22.22
⁄16 7.93 1 25.4
in. mm in. mm
5 3 3
⁄8 15.87 1 ⁄8 35
0.010 0.25 ⁄4 19
3 7
⁄4 19 1 ⁄8 47.6
⁄64 1.19 5 127
13 1 1
⁄16 20.63 3 ⁄2 89 ⁄2 12.7
FIG. 4 Dimensional Details of Clamping Plate of Embrittlement
FIG. 5 Dimensional Details of Test Specimen
Detector
NOTE 5—The surface to be studied is the stressed area, which starts 6
and extends about 25 mm (1 in.) toward the adjusting screw.
mm ( ⁄4 in.) above the spot corresponding to the opening in the test block
D807–00
sure that the small leakage hole is cleaned out, then wipe the
groove clean.Treat the stud threads with graphite suspended in
oil (Note 10).
NOTE 9—When received from the manufacturer the detector is already
assembled with the specimen in position and should be steam tight. It is
recommended that the specimen not be removed from the detector until
after the first test is completed.
NOTE 10—Alittlegraphitesuspendedinoilappliedtothethreadsofthe
studs and the adjusting screw will minimize seizing. Use kerosine instead
of oil if the pressure is greater than 3.5 MPa (500 psi).
8.2 To assemble the specimen and the detector, center the
specimen with the smoothed surface facing the groove of the
NOTE—Rectangular Bars of 1-in. (25 mm) Cold-Rolled Plate Held
blocksothattheendwiththeadjustingscrewholeisflushwith
Togetherby1-in.Bolts.DistanceBetweenBars3 ⁄4 in.(82mm).Pressure
the end of the block not grooved. Place the clamping plate over
Transmitted by a 1 ⁄2 in. (38 mm) Round Bar.
the studs, with the beveled edge inward and toward the end of
FIG. 6 Jig for Bending Specimen After Test
the specimen containing the adjusting screw. Place the washers
and nuts on the studs. Tighten alternately and evenly first the
nuts on the top pairs of studs (Note 10) in the center of the
7. Test Specimens
detector block, thus forcing the surface of the test specimen to
1 3
7.1 Cut test specimens 13 by 19 by 127 mm ( ⁄2 by ⁄4 by 5 conform to the curvature of the groove. Then tighten the nuts
1 3
in.) from 13 by 19-mm ( ⁄2 by ⁄4-in.) cold-finished bar stock on the bottom pair of studs. Finally tighten the nuts on the top
(Note6andNote7)conformingtoGrade1020ofSpecification pair of studs to bring the surfaces close enough together so that
A 108. the small hole in the detector block groove is sealed.
NOTE 6—Where specimens of cold-rolled steel have been cracked, NOTE 11—There shall be no leakage from the detector when the valves
similar specimens machined from boiler plate conforming to Specification are opened and water at full boiler pressure flows through the block.
A 515/A 515M, or hot-rolled steel of comparable composition may be
8.3 Insert the adjusting screw in the specimen and turn it
tested to determine the severity of the embrittling condition. Hot-rolled
down with the fingers until it just touches the block.
steel has proved less susceptible to cracking than cold-rolled steel.
NOTE 7—Alloy steels are often more susceptible for cracking than the
9. Installation of Detector
standard cold-rolled steel specified for test specimens. Where the water
tested is used in alloy-steel boilers, it is desirable that the test specimen be
9.1 Connect the assembled detector to the operating boiler
prepared from the same material or from bars of similar composition and
so that boiler water will circulate through the block (Note 12).
physical properties.
Flush clean the inlet line to the detector before the detector is
7.2 Finishthetestsurfaceofthespecimenbyeithergrinding
attached.
with a surface grinder to a finish comparable to that produced
NOTE 12—The detector may be installed in a bypass to a continuous
by No. 2 metallographic polishing paper, or milling to remove
blow-down line or in a recirculating line if one is available. The effluent
surface imperfections and smoothing with No. 2 metallo-
from the detector may be returned to the boiler or discharged to waste.
graphic paper to remove the cutter marks. Grind and polish
9.2 Maintain the temperature and pressure of the water
along the length of the specimen. If the specimen surface still
circulating through the detector block substantially the same as
shows visible flaws, such as holes, oxide, or rolling marks,
the temperature (Note 13) and pressure of the water in the
after0.2mm(0.01in.)hasbeenremoved,discardthespecimen
boiler. Determine the temperature by means of a thermocouple
and prepare another one.
or thermometer inserted in a small hole provided for it in the
7.3 Bevel the edges of the test surface 5°, as shown in Fig.
block.
5.
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