ASTM G134-95

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 G32. 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.
1.6 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.

General Information

• Status: Historical
• Publication Date: 31-Dec-2000
• Technical Committee: G02 - Wear and Erosion
• Drafting Committee: G02.10 - Erosion by Solids and Liquids

Relations

• Replaced By: ASTM G134-95(2001)e1 - Standard Test Method for Erosion of Solid Materials by a Cavitating Liquid Jet
• Effective Date: 01-Jan-2001
• Referred By: ASTM G32-16(2021)e1 - Standard Test Method for Cavitation Erosion Using Vibratory Apparatus
• Effective Date: 01-Jan-2001
• Referred By: ASTM G73-10(2021) - Standard Test Method for Liquid Impingement Erosion Using Rotating Apparatus
• Effective Date: 01-Jan-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: G 134 – 95
Standard Test Method for
Erosion of Solid Materials by a Cavitating Liquid Jet
This standard is issued under the fixed designation G 134; 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 2. Referenced Documents
1.1 This test method covers a test that can be used to 2.1 ASTM Standards:
compare the cavitation erosion resistance of solid materials. A A 276 Specification for Stainless Steel Bars and Shapes
submerged cavitating jet, issuing from a nozzle, impinges on a B 160 Specification for Nickel Rod and Bar
test specimen placed in its path so that cavities collapse on it, B 211 Specification for Aluminum and Aluminum Alloy
thereby causing erosion. The test is carried out under specified Bar, Rod, and Wire
conditions in a specified liquid, usually water. This test method D 1193 Specification for Reagent Water
can also be used to compare the cavitation erosion capability of E 691 Practice for Conducting an Interlaboratory Study to
various liquids. Determine the Precision of a Test Method
1.2 This test method specifies the nozzle and nozzle holder G 32 Test Method for Cavitation Erosion Using Vibratory
shape and size, the specimen size and its method of mounting, Apparatus
and the minimum test chamber size. Procedures are described G 40 Terminology Relating to Wear and Erosion
for selecting the standoff distance and one of several standard G 73 Practice for Liquid Impingement Erosion Testing
test conditions. Deviation from some of these conditions is 2.2 ASTM Adjuncts:
permitted where appropriate and if properly documented. Manufacturing Drawings of the Apparatus
Guidance is given on setting up a suitable apparatus, test and
3. Terminology
reporting procedures, and the precautions to be taken. Standard
reference materials are specified; these must be used to verify 3.1 Definitions—See Terminology G 40 for definitions of
terms relating to cavitation erosion. For convenience, defini-
the operation of the facility and to define the normalized
erosion resistance of other materials. tions of some important terms used in this test method are
quoted below from Terminology G 40 – 90a.
1.3 Two types of tests are encompassed, one using test
liquids which can be run to waste, for example, tap water, and 3.1.1 cavitation—the formation and collapse, within a liq-
uid, of cavities or bubbles that contain vapor or gas, or both.
the other using liquids which must be recirculated, for ex-
ample, reagent water or various oils. Slightly different test 3.1.1.1 Discussion—In general, cavitation originates from a
decrease in static pressure in the liquid. It is distinguished in
circuits are required for each type.
1.4 This test method provides an alternative to Test Method this way from boiling, which originates from an increase in
liquid temperature. There are certain situations where it may be
G 32. In that method, cavitation is induced by vibrating a
submerged specimen at high frequency (20 kHz) with a difficult to make a clear distinction between cavitation and
boiling, and the more general definition that is given here is,
specified amplitude. In the present method, cavitation is
therefore, preferred.
generated in a flowing system so that both the jet velocity and
the downstream pressure (which causes the bubble collapse) 3.1.1.2 Discussion—In order to erode a solid surface by
cavitation, it is necessary for the cavitation bubbles to collapse
can be varied independently.
1.5 The values stated in SI units are to be regarded as the on or close to that surface.
3.1.2 cavitation erosion—progressive loss of original mate-
standard. The values given in parentheses are for information
only. rial from a solid surface due to continued exposure to cavita-
tion.
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.1.3 cumulative erosion—the total amount of material lost
from a solid surface during all exposure periods since it was
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
Annual Book of ASTM Standards, Vol 01.03.
Annual Book of ASTM Standards, Vol 02.04.
Annual Book of ASTM Standards, Vol 02.02.
1 5
This test method is under the jurisdiction of ASTM Committee G02 on Wear Annual Book of ASTM Standards, Vol 11.01.
and Erosion and is the direct responsibility of Subcommittee G02.10 on Erosion by Annual Book of ASTM Standards, Vol 14.02.
Solids and Liquids. Annual Book of ASTM Standards, Vol 03.02.
Current edition approved Oct. 10, 1995. Published March 1996. Available from ASTM Headquarters, Order PCN ADJG0134.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
G 134
first exposed to cavitation or impingement as a newly finished 3.2 Definitions of Terms Specific to This Standard:
surface. Unless otherwise indicated by the context, it is implied
3.2.1 cavitating jet—a continuous liquid jet (usually sub-
that the conditions of cavitation or impingement have remained
merged) in which cavitation is induced by the nozzle design or
the same throughout all exposure periods, with no intermediate
sometimes by a center body. See also jet cavitation.
refinishing of the surface.
3.2.2 cavitation number, s—a dimensionless number that
3.1.4 cumulative erosion rate—the cumulative erosion di-
measures the tendency for cavitation to occur in a flowing
vided by the corresponding cumulative exposure duration, that
stream of liquid, and that, for the purpose of this test method,
is, the slope of a line from the origin to a specified point on the
is defined by the equation:
cumulative erosion-time curve.
~p 2 p !
d v
s5 (1)
3.1.5 cumulative erosion-time curve—a plot of cumulative
rV
erosion versus cumulative exposure time, usually determined
by periodic interruption of the test and weighing of the
where:
specimen. This is the primary record of an erosion test. Most
p 5 vapor pressure,
v
other characteristics, such as the incubation period, maximum
p 5 static pressure in the downstream chamber,
d
erosion rate, terminal erosion rate, and erosion ratetime curve,
V 5 jet velocity, and
are derived from it.
r5 liquid density.
3.1.6 flow cavitation—cavitation caused by a decrease in
3.2.2.1 For liquid flow through any orifice
static pressure induced by changes in velocity of a flowing
liquid. Typically, this may be caused by flow around an
r V 5 p 2 p . (2)
u d
obstacle or through a constriction, or relative to a blade or foil.
A cavitation cloud or “cavitating wake” generally trails from
where:
some point adjacent to the obstacle or constriction to some
p 5 upstream pressure.
u
distance downstream, the bubbles being formed at one place
3.2.2.2 All pressures are absolute. For erosion testing by
and collapsing at another.
this test method, the cavitating flow in the nozzle is choked, so
3.1.7 incubation period—in cavitation and impingement
that the downstream pressure, as seen by the flow, is equal to
erosion, the initial stage of the erosion rate-time pattern during
the vapor pressure. The cavitation number thus reduces to
which the erosion rate is zero or negligible compared to later
p 2 p
d v
stages. Also, the exposure duration associated with this stage.
s5 (3)
p 2 p
u v
(Quantitatively it is sometimes defined as the intercept on the
which for many liquids and at many temperatures can be
time or exposure axis, of a straight line extension of the
approximated by:
maximum-slope portion of the cumulative erosion-time curve).
3.1.8 maximum erosion rate—the maximum instantaneous
p
d
s5 (4)
erosion rate in a test that exhibits such a maximum followed by
p
u
decreasing erosion rates. (Occurrence of such a maximum is
since
typical of many cavitation and liquid impingement tests. In
p . p . p (5)
u d v
some instances it occurs as an instantaneous maximum, in
others as a steady-state maximum which persists for some
3.2.3 jet cavitation—the cavitation generated in the vortices
time.)
which travel in sequence singly or in clouds in the shear layer
3.1.9 normalized erosion resistance, N —the volume loss around a submerged jet. It can be amplified by the nozzle
e
rate of a test material, divided into the rate of volume loss of a
design so that vortices form in the vena contracta region inside
specified reference material similarly tested and similarly the nozzle.
analyzed. Similarly analyzed means that the two erosion rates
3.2.4 stand-off distance—in this test method, the distance
must be determined for corresponding portions of the erosion
between the inlet edge of the nozzle and the target face of the
rate-time pattern; for instance, the maximum erosion rate or the
specimen. It is thus defined because the location and shape of
terminal erosion rate.
the inlet edge determine the location of the vena contracta and
3.1.9.1 Discussion—A recommended complete wording has the initiation of cavitation.
the form, “The normalized erosion resistance of (test material)
3.2.5 tangent erosion rate—the slope of a straight line
relative to (reference material) based on (criterion of data
drawn through the origin and tangent to the knee of the
analysis) is (numerical value).”
cumulative erosion-time curve, when the shape of that curve
3.1.10 normalized incubation resistance, N —the incuba- has the characteristic S-shape pattern that permits this. In such
o
tion period of a test material, divided by the incubation period cases, the tangent erosion rate also represents the maximum
of a specified reference material similarly tested and similarly cumulative erosion rate exhibited during the test.
analyzed.
3.2.6 vena contracta—the smallest locally occurring diam-
3.1.11 terminal erosion rate—the final steady-state erosion eter of the main flow of a fluid after it enters into a nozzle or
rate that is reached (or appears to be approached asymptoti- orifice from a larger conduit or a reservoir. At this point the
cally) after the erosion rate has declined from its maximum main or primary flow is detached from the solid boundaries,
value. This occurs in some, but not all, cavitation and liquid and vortices or recirculating secondary flow patterns are
impingement tests. formed in the intervening space.
G 134
4. Summary of Test Method liquid drop impingement, if the use of Practice G 73 is not
feasible. However, this is not recommended for elastomeric
4.1 This test method produces a submerged cavitating jet
coatings, composites, or other nonmetallic aerospace materials.
which impinges upon a stationary specimen, also submerged,
5.5 The mechanisms of cavitation erosion and liquid im-
causing cavitation bubbles to collapse on that specimen and
pingement erosion are not fully understood and may vary,
thereby to erode it. This test method generally utilizes a
depending on the detailed nature, scale, and intensity of the
commercially available positive displacement pump fitted with
liquid/solid interactions. Erosion resistance may, therefore,
a hydraulic accumulator to damp out pulsations. The pump
arise from a mix of properties rather than a single property, and
delivers test liquid through a small sharp-entry cylindrical-bore
has not yet been successfully correlated with other indepen-
nozzle, which discharges a jet of liquid into a chamber at a
dently measurable material properties. For this reason, the
controlled pressure. Cavitation starts in the vena contracta
consistency of results between different test methods (for
region of the jet within the length of the nozzle; it is stabilized
example, vibratory, rotating disk, or cavitating jet) or under
by the cylindrical bore and it emerges, appearing to the eye as
different experimental conditions is not very good. Small
a cloud which is visible around the submerged liquid jet. A
differences between two materials are probably not significant,
button type specimen is placed in the path of the jet at a
and their relative ranking could well be reversed in another
specified standoff distance from the entry edge of the nozzle.
test.
Cavitation bubbles collapse on the specimen, thus causing
5.6 Because of the nonlinear nature of the erosion-time
erosion. Both the upstream and the downstream chamber
curve in cavitation erosion, the shape of that curve must be
pressures and the temperature of the discharging liquid must be
considered in making comparisons and drawing conclusions.
controlled and monitored. The test specimen is weighed
Simply comparing the cumulative mass loss at the same
accurately before testing begins and again during periodic
cumulative test time for all materials will not give a reliable
interruptions of the test, in order to obtain a history of mass
comparison.
loss versus time (which is not linear). Appropriate interpreta-
tion of the cumulative erosion-time curve derived from these
6. Apparatus
measurements permits comparisons to be drawn between
6.1 General Arrangement:
different materials, different test conditions, or between differ-
6.1.1 Fig. 1 shows an arrangement of the test chamber. A
ent liquids. A typical test rig can be built using a 2.5-kW pump
cavitating jet supplied from a constant pressure source (p )
u
capable of producing 21-MPa pressure. The standard nozzle
discharges, through a long-orifice nozzle (Fig. 2), into a
bore diameter is 0.4 mm, but this may be changed if required
chamber held at specified constant pressure (p ). A flat-ended
d
for specialized tests.
cylindrical specimen (Fig. 3) is mounted coaxially with the
nozzle so that the stand-off distance between the nozzle inlet
5. Significance and Use
edge and the specimen face can be set at any required value. A
5.1 This test method may be used to estimate the relative
movable jet deflector (Fig. 1, Item 11) may be provided to
resistances of materials to cavitation erosion, as may be
protect the specimen while test conditions are being set up.
encountered for instance in pumps, hydraulic turbines, valves,
Windows may be provided at both sides of the chamber so that
hydraulic dynamometers and couplings, bearings, diesel engine
the erosion process can be observed. Unless the complete test
cylinder liners, ship propellers, hydrofoils, internal flow pas-
chamber assembly can withstand maximum operating pres-
sages, and various components of fluid power systems or fuel
sures that could occur under any conceivable circumstances, a
systems of diesel engines. It can also be used to compare
pres
...