ASTM G134-95(2010)e1
(Test Method)Standard Test Method for Erosion of Solid Materials by a Cavitating Liquid Jet
Standard Test Method for Erosion of Solid Materials by a Cavitating Liquid Jet
SCOPE
1.1 This test method covers a test that can be used to compare the cavitation erosion resistance of solid materials. A submerged cavitating jet, issuing from a nozzle, impinges on a test specimen placed in its path so that cavities collapse on it, thereby causing erosion. The test is carried out under specified conditions in a specified liquid, usually water. This test method can also be used to compare the cavitation erosion capability of various liquids.
1.2 This test method specifies the nozzle and nozzle holder shape and size, the specimen size and its method of mounting, and the minimum test chamber size. Procedures are described for selecting the standoff distance and one of several standard test conditions. Deviation from some of these conditions is permitted where appropriate and if properly documented. Guidance is given on setting up a suitable apparatus, test and reporting procedures, and the precautions to be taken. Standard reference materials are specified; these must be used to verify the operation of the facility and to define the normalized erosion resistance of other materials.
1.3 Two types of tests are encompassed, one using test liquids which can be run to waste, for example, tap water, and the other using liquids which must be recirculated, for example, reagent water or various oils. Slightly different test circuits are required for each type.
1.4 This test method provides an alternative to Test Method G 32. In that method, cavitation is induced by vibrating a submerged specimen at high frequency (20 kHz) with a specified amplitude. In the present method, cavitation is generated in a flowing system so that both the jet velocity and the downstream pressure (which causes the bubble collapse) can be varied independently.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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: G134 − 95 (Reapproved 2010)
Standard Test Method for
Erosion of Solid Materials by Cavitating Liquid Jet
This standard is issued under the fixed designation G134; 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.
ε NOTE—Updated Section 3 to reflect Terminology G40–10b editorially in December 2010.
1. Scope 1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers a test that can be used to
responsibility of the user of this standard to establish appro-
compare the cavitation erosion resistance of solid materials.A
priate safety and health practices and determine the applica-
submerged cavitating jet, issuing from a nozzle, impinges on a
bility of regulatory limitations prior to use.
test specimen placed in its path so that cavities collapse on it,
thereby causing erosion. The test is carried out under specified
2. Referenced Documents
conditions in a specified liquid, usually water.This test method
canalsobeusedtocomparethecavitationerosioncapabilityof 2.1 ASTM Standards:
various liquids. A276 Specification for Stainless Steel Bars and Shapes
B160 Specification for Nickel Rod and Bar
1.2 This test method specifies the nozzle and nozzle holder
B211 Specification for Aluminum and Aluminum-Alloy
shape and size, the specimen size and its method of mounting,
Rolled or Cold Finished Bar, Rod, and Wire
and the minimum test chamber size. Procedures are described
D1193 Specification for Reagent Water
for selecting the standoff distance and one of several standard
E691 Practice for Conducting an Interlaboratory Study to
test conditions. Deviation from some of these conditions is
Determine the Precision of a Test Method
permitted where appropriate and if properly documented.
G32 Test Method for Cavitation Erosion Using Vibratory
Guidance is given on setting up a suitable apparatus, test and
Apparatus
reportingprocedures,andtheprecautionstobetaken.Standard
G40 Terminology Relating to Wear and Erosion
reference materials are specified; these must be used to verify
G73 Test Method for Liquid Impingement Erosion Using
the operation of the facility and to define the normalized
Rotating Apparatus
erosion resistance of other materials.
2.2 ASTM Adjuncts:
1.3 Two types of tests are encompassed, one using test
Manufacturing Drawings of the Apparatus
liquids which can be run to waste, for example, tap water, and
the other using liquids which must be recirculated, for
3. Terminology
example, reagent water or various oils. Slightly different test
circuits are required for each type. 3.1 SeeTerminologyG40fordefinitionsoftermsrelatingto
cavitation erosion. For convenience, definitions of some im-
1.4 This test method provides an alternative to Test Method
portant terms used in this test method are reproduced below.
G32. In that method, cavitation is induced by vibrating a
submerged specimen at high frequency (20 kHz) with a
3.2 Definitions:
specified amplitude. In the present method, cavitation is 3.2.1 cavitation, n—the formation and subsequent collapse,
generated in a flowing system so that both the jet velocity and within a liquid, of cavities or bubbles that contain vapor or a
the downstream pressure (which causes the bubble collapse) mixture of vapor and gas.
can be varied independently. 3.2.1.1 Discussion—Cavitation originates from a local de-
crease in hydrostatic pressure in the liquid, usually produced
1.5 The values stated in SI units are to be regarded as
by motion of the liquid (see flow cavitation) or of a solid
standard. No other units of measurement are included in this
standard.
1 2
This test method is under the jurisdiction of ASTM Committee G02 on Wear For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Erosion and is the direct responsibility of Subcommittee G02.10 on Erosion by contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Solids and Liquids. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2010. Published December 2010. Originally the ASTM website.
approved in 1995. Last previous edition approved in 2006 as G134–95(2006). DOI: Available from ASTM International Headquarters. Order Adjunct No.
10.1520/G0134-95R10E01. ADJG0134.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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G134 − 95 (2010)
boundary (see vibratory cavitation). It is distinguished in this typical of many cavitation and liquid impingement tests. In
way from boiling, which originates from an increase in liquid some instances, it occurs as an instantaneous maximum, in
temperature. others as a steady-state maximum which persists for some
3.2.1.2 Discussion—The term cavitation, by itself, should time. G40
not be used to denote the damage or erosion of a solid surface
3.2.9 normalized erosion resistance, N , n—in cavitation
e
that can be caused by it; this effect of cavitation is termed
and liquid impingement erosion, a measure of the erosion
cavitation damage or cavitation erosion. To erode a solid
resistance of a test material relative to that of a specified
surface, bubbles or cavities must collapse on or near that
reference material, calculated by dividing the volume loss rate
surface. G40
of the reference material by that of the test material, when both
3.2.2 cavitation erosion, n—progressive loss of original
are similarly tested and similarly analyzed. By “similarly
material from a solid surface due to continued exposure to
analyzed,” it is meant that the two erosion rates must be
cavitation. G40
determined for corresponding portions of the erosion rate time
3.2.3 cumulative erosion, n—in cavitation and impingement pattern; for instance, the maximum erosion rate or the terminal
erosion, the total amount of material lost from a solid surface
erosion rate.
during all exposure periods since it was first exposed to
3.2.9.1 Discussion—Arecommended complete wording has
cavitation or impingement as a newly-finished surface. (More
the form, “The normalized erosion resistance of (test material)
specific terms that may be used are cumulative mass loss,
relative to (reference material) based on (criterion of data
cumulative volume loss,or cumulative mean depth of erosion.
analysis) is (numerical value).” G40
See also cumulative erosion-time curve.)
3.2.10 normalized incubation resistance, N,n—the nomi-
o
3.2.3.1 Discussion—Unless otherwise indicated by the
nal incubation period of a test material, divided by the nominal
context, it is implied that the conditions of cavitation or
incubation period of a specified reference material similarly
impingement have remained the same throughout all exposure
tested and similarly analyzed. (See also normalized erosion
periods, with no intermediate refinishing of the surface. G40
resistance.) G40
3.2.4 cumulative erosion rate, n—the cumulative erosion at
3.2.11 terminal erosion rate, n—in cavitation or liquid
a specified point in an erosion test divided by the correspond-
impingement erosion, the final steady-state erosion rate that is
ing cumulative exposure duration; that is, the slope of a line
reached (or appears to be approached asymptotically) after the
from the origin to the specified point on the cumulative
erosion rate has declined from its maximum value. (See also
erosion-time curve. (Synonym: average erosion rate) G40
terminal period and erosion rate-time pattern.) G40
3.2.5 cumulative erosion-time curve, n—in cavitation and
impingement erosion, a plot of cumulative erosion versus 3.3 Definitions of Terms Specific to This Standard:
cumulative exposure duration, usually determined by periodic
3.3.1 cavitating jet, n—a continuous liquid jet (usually
interruption of the test and weighing of the specimen. This is
submerged)inwhichcavitationisinducedbythenozzledesign
the primary record of an erosion test. Most other
or sometimes by a center body. See also jet cavitation.
characteristics, such as the incubation period, maximum ero-
3.3.2 cavitation number, σ—a dimensionless number that
sionrate,terminalerosionrate,anderosionrate-timecurve,are
measures the tendency for cavitation to occur in a flowing
derived from it. G40
stream of liquid, and that, for the purpose of this test method,
3.2.6 flow cavitation, n—cavitation caused by a decrease in
isdefinedbythefollowingequation.Allpressuresareabsolute.
local pressure induced by changes in velocity of a flowing
p 2 p
liquid. Typically, this may be caused by flow around an ~ !
d v
σ 5 (1)
obstacle or through a constriction, or relative to a blade or foil.
ρV
A cavitation cloud or “cavitating wake” generally trails from 2
some point adjacent to the obstacle or constriction to some
where:
distance downstream, the bubbles being formed at one place
p = vapor pressure,
v
and collapsing at another. G40
p = static pressure in the downstream chamber,
d
3.2.7 incubation period, n—in cavitation and impingement
V = jet velocity, and
erosion, the initial stage of the erosion rate-time pattern during
ρ = liquid density.
which the erosion rate is zero or negligible compared to later
3.3.2.1 For liquid flow through any orifice:
stages. Also, the exposure duration associated with this stage.
(Quantitatively it is sometimes defined as the intercept on the
ρ V 5 p 2 p (2)
u d
time or exposure axis, of a straight line extension of the 2
maximum-slopeportionofthecumulativeerosion-timecurve.)
where:
G40
p = upstream pressure.
u
3.2.8 maximum erosion rate, n—in cavitation and liquid
impingement erosion, the maximum instantaneous erosion rate 3.3.2.2 For erosion testing by this test method, the cavitat-
in a test that exhibits such a maximum followed by decreasing ing flow in the nozzle is choked, so that the downstream
erosion rates. (See also erosion rate-time pattern.)
pressure, as seen by the flow, is equal to the vapor pressure.
3.2.8.1 Discussion—Occurrence of such a maximum is The cavitation number thus reduces to:
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G134 − 95 (2010)
p 2 p ent liquids.Atypical test rig can be built using a 2.5-kWpump
d v
σ 5 (3)
p 2 p capable of producing 21-MPa pressure. The standard nozzle
u v
bore diameter is 0.4 mm, but this may be changed if required
which for many liquids and at many temperatures can be
for specialized tests.
approximated by:
p
d
5. Significance and Use
σ 5 (4)
p
u
5.1 This test method may be used to estimate the relative
since
resistances of materials to cavitation erosion, as may be
p .p .p (5)
encountered for instance in pumps, hydraulic turbines, valves,
u d v
hydraulicdynamometersandcouplings,bearings,dieselengine
3.3.3 jet cavitation, n—the cavitation generated in the vor-
cylinder liners, ship propellers, hydrofoils, internal flow
tices which travel in sequence singly or in clouds in the shear
passages, and various components of fluid power systems or
layer around a submerged jet. It can be amplified by the nozzle
fuel systems of diesel engines. It can also be used to compare
design so that vortices form in the vena contracta region inside
erosion produced by different liquids under the conditions
the nozzle.
simulated by the test. Its general applications are similar to
3.3.4 stand-off distance, n—in this test method, the distance
those of Test Method G32.
between the inlet edge of the nozzle and the target face of the
specimen. It is thus defined because the location and shape of 5.2 In this test method cavitation is generated in a flowing
the inlet edge determine the location of the vena contracta and system. Both the velocity of flow which causes the formation
the initiation of cavitation.
ofcavitiesandthechamberpressureinwhichtheycollapsecan
be changed easily and independently, so it is possible to study
3.3.5 tangent erosion rate, n—the slope of a straight line
the effects of various parameters separately. Cavitation condi-
drawn through the origin and tangent to the knee of the
tions can be controlled easily and precisely. Furthermore, if
cumulative erosion-time curve, when the shape of that curve
tests are performed at constant cavitation number (σ), it is
has the characteristic S-shape pattern that permits this. In such
possible, by suitably altering the pressures, to accelerate or
cases, the tangent erosion rate also represents the maximum
slow down the testing process (see 11.2 and Fig. A2.2).
cumulative erosion rate exhibited during the test.
3.3.6 vena contracta, n—the smallest locally occurring di-
5.3 This test method with standard conditions should not be
ameter of the main flow of a fluid after it enters into a nozzle
used to rank materials for applications where electrochemical
or orifice from a larger conduit or a reservoir.At this point the
corrosion or solid particle impingement plays a major role.
main or primary flow is detached from the solid boundaries,
However, it could be adapted to evaluate erosion-corrosion
and vortices or recirculating secondary flow patterns are
effects if the appropriate liquid and cavitation number, for the
formed in the intervening space.
service conditions of interest, are used (see 11.1).
4. Summary of Test Method
5.4 For metallic materials, this test method could also be
used as a screening test for applications subjected to high-
4.1 This test method produces a submerged cavitating jet
speed liquid drop impingement, if the use of Practice G73 is
which impinges upon a stationary specimen, also submerged,
notfeasible.However,thisisnotrecommendedforelastomeric
causing cavitation bubbles to collapse on that specimen and
coatings,composites,orothernonmetallicaerospacematerials.
thereby to erode it. This test method generally utilizes a
commercially available positive displacement pump fitted with
5.5 The mechanisms of cavitation erosion and liquid im-
a hydraulic accumulator to damp out pulsations. The pump
pingement erosion are not fully understood and may vary,
deliverstestliquidthroughasmallsharp-entrycylindrical-bore
depending on the detailed nature, scale, and intensity of the
nozzle, which discharges a jet of liquid into a chamber at a
liquid/solid interactions. Erosion resistance may, therefore,
controlled pressure. Cavitation starts in the vena contracta
arisefromamixofpropertiesratherthanasingleproperty,and
region of the jet within the length of the nozzle; it is stabilized
has not yet been successfully correlated with other indepen-
by the cylindrical bore and it emerges, appearing to the eye as
dently measurable material properties. For
...
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