ASTM A418/A418M-05
(Test Method)Standard Test Method for Ultrasonic Examination of Turbine and Generator Steel Rotor Forgings
Standard Test Method for Ultrasonic Examination of Turbine and Generator Steel Rotor Forgings
SCOPE
1.1 This test method for ultrasonic examination applies to turbine and generator steel rotor forgings covered by Specifications A 293, A 469/A 469M, and A 470. This standard shall be used for contact testing only.
1.2 This test method describes a basic procedure of ultrasonically inspecting turbine and generator rotor forgings. It shall in no way restrict the use of other ultrasonic methods such as reference block calibrations when required by the applicable procurement documents nor is it intended to restrict the use of new and improved ultrasonic test equipment and methods as they are developed. The procedure utilizes different calibration techniques than had been used in previous issues. The frequency or amplitudes of recordable indications should not be interpreted necessarily as a change in quality of the product being examined.
1.3 This test method is intended to provide a means of inspecting cylindrical forgings so that the inspection sensitivity at the forging center line or bore surface is constant, independent of the forging or bore diameter. To this end, inspection sensitivity multiplication factors have been computed from theoretical analysis, with experimental verification. These are plotted in (bored rotors) and (solid rotors), for a true inspection frequency of 2.25 MHz, and an acoustic velocity of 2.30 105 in./s [5.85 105 cm/s]. Means of converting to other sensitivity levels are provided in . (Sensitivity multiplication factors for other frequencies may be derived in accordance with and of .)
1.4 Considerable verification data for this method have been generated which indicate that even under controlled conditions very significant uncertainties may exist in estimating natural discontinuities in terms of minimum equivalent size flat-bottom holes. The possibility exists that the estimated minimum areas of natural discontinuities in terms of minimum areas of the comparison flat-bottom holes may differ by 20 dB (factor of 10) in terms of actual areas of natural discontinuities. This magnitude of inaccuracy does not apply to all results but should be recognized as a possibility. Rigid control of the actual frequency used, the coil bandpass width if tuned instruments are used, and so forth, tend to reduce the overall inaccuracy which is apt to develop.
1.5 This test method for inspection applies to solid cylindrical forgings having outer diameters of not less than 2.5 in. [64 mm] nor greater than 100 in. [2540 mm]. It also applies to cylindrical forgings with concentric cylindrical bores having wall thicknesses of 2.5 [64 mm] in. or greater, within the same outer diameter limits as for solid cylinders. For solid sections less than 15 in. [380 mm] in diameter and for bored cylinders of less than 7.5 in. [190 mm] wall thickness the transducer used for the inspection will be different than the transducer used for larger sections.
1.6 This test method is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract specifies the applicable M specification designation (SI units), the inch-pound units shall apply. The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the test method, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
1.7 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supplementary requirements shall apply only when specified individually by the purchaser in the purchase order or contract.
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 regulat...
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Designation: A 418/A 418M – 05
Standard Test Method for
Ultrasonic Examination of Turbine and Generator Steel
1
Rotor Forgings
ThisstandardisissuedunderthefixeddesignationA418/A418M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope bottom holes. The possibility exists that the estimated mini-
mum areas of natural discontinuities in terms of minimum
1.1 This test method for ultrasonic examination applies to
areas of the comparison flat-bottom holes may differ by 20 dB
turbine and generator steel rotor forgings covered by Specifi-
(factorof10)intermsofactualareasofnaturaldiscontinuities.
cations A293, A469/A469M, and A470. This standard shall
This magnitude of inaccuracy does not apply to all results but
be used for contact testing only.
should be recognized as a possibility. Rigid control of the
1.2 This test method describes a basic procedure of ultra-
actual frequency used, the coil bandpass width if tuned
sonically inspecting turbine and generator rotor forgings. It
instruments are used, and so forth, tend to reduce the overall
shallinnowayrestricttheuseofotherultrasonicmethodssuch
inaccuracy which is apt to develop.
asreferenceblockcalibrationswhenrequiredbytheapplicable
1.5 This test method for inspection applies to solid cylin-
procurement documents nor is it intended to restrict the use of
drical forgings having outer diameters of not less than 2.5 in.
new and improved ultrasonic test equipment and methods as
[64 mm] nor greater than 100 in. [2540 mm]. It also applies to
they are developed.The procedure utilizes different calibration
cylindrical forgings with concentric cylindrical bores having
techniques than had been used in previous issues. The fre-
wall thicknesses of 2.5 [64 mm] in. or greater, within the same
quency or amplitudes of recordable indications should not be
outer diameter limits as for solid cylinders. For solid sections
interpreted necessarily as a change in quality of the product
less than 15 in. [380 mm] in diameter and for bored cylinders
being examined.
oflessthan7.5in.[190mm]wallthicknessthetransducerused
1.3 This test method is intended to provide a means of
for the inspection will be different than the transducer used for
inspectingcylindricalforgingssothattheinspectionsensitivity
larger sections.
at the forging center line or bore surface is constant, indepen-
1.6 This test method is expressed in both inch-pound units
dent of the forging or bore diameter. To this end, inspection
and in SI units; however, unless the purchase order or contract
sensitivity multiplication factors have been computed from
specifies the applicable M specification designation (SI units),
theoretical analysis, with experimental verification. These are
the inch-pound units shall apply. The values stated in either
plotted in Fig. 1 (bored rotors) and Fig. 2 (solid rotors), for a
inch-pound units or SI units are to be regarded separately as
true inspection frequency of 2.25 MHz, and an acoustic
5 5
standard. Within the test method, the SI units are shown in
velocity of 2.30 3 10 in./s [5.85 3 10 cm/s]. Means of
brackets. The values stated in each system may not be exact
converting to other sensitivity levels are provided in Fig. 3.
equivalents;therefore,eachsystemshallbeusedindependently
(Sensitivitymultiplicationfactorsforotherfrequenciesmaybe
of the other. Combining values from the two systems may
derived in accordance with X1.1 and X1.2 of Appendix X1.)
result in nonconformance with the standard.
1.4 Considerableverificationdataforthismethodhavebeen
1.7 Supplementary requirements of an optional nature are
generated which indicate that even under controlled conditions
provided for use at the option of the purchaser. The supple-
very significant uncertainties may exist in estimating natural
mentary requirements shall apply only when specified indi-
discontinuities in terms of minimum equivalent size flat-
vidually by the purchaser in the purchase order or contract.
1.8 This standard does not purport to address all of the
1
This test method is under the jurisdiction of ASTM Committee A01 on Steel, safety concerns, if any, associated with its use. It is the
Stainless Steel and RelatedAlloys, and is the direct responsibility of Subcommittee
responsibility of the user of this standard to establish appro-
A01.06 on Steel Forgings and Billets.
priate safety and health practices and determine the applica-
Current edition approved Sept. 1, 2005. Published September 2005. Originally
bility of regulatory limitations prior to use.
approved in 1957. Last previous edition approved in 2003 as A418–99(2003).
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