ASTM F2523-13(2020)
(Practice)Standard Practice for Blowout Resistance of Room-Temperature Vulcanized Elastomers
Standard Practice for Blowout Resistance of Room-Temperature Vulcanized Elastomers
SIGNIFICANCE AND USE
5.1 This practice may be used to determine the viability of an RTV sealant to withstand pressure leak testing before cure at maximum gap conditions of a system. This practice may be used to indicate an RTV’s acceptability to undergo an assembly line leak check without causing a leak path due to material blow out.
SCOPE
1.1 This practice provides a means to determine the blowout resistance of a room-temperature vulcanized elastomer system (RTV) using a standard fixture.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F2523 − 13 (Reapproved 2020)
Standard Practice for
Blowout Resistance of Room-Temperature Vulcanized
Elastomers
This standard is issued under the fixed designation F2523; 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 3.2 Definitions of Terms Specific to This Standard:
3.2.1 blowout, n—disruption of the uncured RTV integrity
1.1 Thispracticeprovidesameanstodeterminetheblowout
inajointfromsystempressurizationresultinginsuddenlossof
resistance of a room-temperature vulcanized elastomer system
pressure.
(RTV) using a standard fixture.
3.2.2 T–joint, n—interface created in a sealing surface
1.2 The values stated in SI units are to be regarded as
where three structural components meet.
standard. No other units of measurement are included in this
3.2.2.1 Discussion—This interface may exist as a small gap
standard.
requiring a material such as room-temperature vulcanized
1.3 This standard does not purport to address all of the
elastomer (RTV) to seal.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.3 Acronyms:
priate safety, health, and environmental practices and deter- 3.3.1 RTV—room-temperature vulcanized elastomer
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
4. Summary of Practice
dance with internationally recognized principles on standard-
4.1 Condensation cures RTVs as a one-component system
ization established in the Decision on Principles for the
cure when exposed to moisture in the ambient air or as
Development of International Standards, Guides and Recom-
two-component systems when those components are mixed
mendations issued by the World Trade Organization Technical
together.RTVsareoftenusedtosealjointswherethreeflanges
Barriers to Trade (TBT) Committee.
meet (T joints) such as an automotive engine’s front cover,
engineblock,andoilpan.Becauseofmachiningandassembly
2. Referenced Documents
tolerance variations, theseTjoints may have a slight misalign-
2.1 ASTM Standards:
ment or gap.We also find gaps in the half-round area of the oil
D907Terminology of Adhesives
pantoblockandinthevalleybetweentheintakemanifoldand
D1566Terminology Relating to Rubber
block on certain V-engines as a result of manufacturing
F2468Classification for Specifying Silicone Adhesives and
tolerances.TheRTVisusedtosealinfluids.Insomeassembly
Sealants for Transportation Applications
line applications, soon after the RTVis applied and the flanges
2.2 SAE Standard:
fastenedtogether,thesystemissubjectedtoanairdecaytestat
SAE J1199Mechanical and Material Requirements for Met-
a designated pressure. This test is used to determine an RTV’s
ric Externally Threaded Steel Fasteners
capability to withstand loss of integrity at this designated
pressure.
3. Terminology
3.1 Definitions—Some terms in this practice are defined in 4.2 When using this practice, one must first determine the
Terminologies D907 and D1566. maximum gap based on stack tolerances of the system. A
two-piece round fixture uses the top portion to mirror the
1 system gap (default gap is 1mm), while the bottom half
ThispracticeisunderthejurisdictionofASTMCommitteeF03onGasketsand
is the direct responsibility of Subcommittee F03.70 on Formed in Place Gaskets.
provides the mating flange and the connection for the pressure
Current edition approved Jan. 1, 2020. Published January 2020. Originally
input. The gap is machined into the top half of the fixture in a
approved in 2005. Last previous edition approved in 2013 as F2523–13. DOI:
“pie slice” 60° angle.Acontinuous bead of RTV is applied to
10.1520/F2523-13R20.
theentirebottomportionofthefixture,thetophalfiscarefully
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
attached, and the fixture is pressurized to the prescribed limits
Standards volume information, refer to the standard’s Document Summary page on
and held for a specified time period. If the RTV is not capable
the ASTM website.
3 ofsealingatthepressureapplied,asuddenlossofpressurewill
Available from Society of Automotive Engineers (SAE), 400 Commonwealth
Dr., Warrendale, PA 15096-0001. occur.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2523 − 13 (2020)
NOTE 1—Torque sequence shall be “crisscross” pattern.
FIG. 1 Aluminum Blowout Fixtures
5. Significance and Use 6.1.1 Aluminum casting, forging, or bar stock with 60
Brinell hardness, minimum.
5.1 This practice may be used to determine the viability of
6.1.2 Surfacefinishshallbeintherangeof0.7to3.2µm Ra.
an RTV sealant to withstand pressure leak testing before cure
6.1.3 Top half of fixture shall have a machined cutout to the
at maximum gap conditions of a system. This practice may be
desired gap depth (1.0 6 0.025 mm default gap), per Fig. 1.
usedtoindicateanRTV’sacceptabilitytoundergoanassembly
Thegapandflangewidtharecriticaldimensionsandshouldbe
line leak check without causing a leak path due to material
controlled to a tight tolerance (62.5% is recommended). All
blow out.
other dimensions are allowed 610 %.
6.1.4 Fournut,bolt,andwashersetsperSAEJ1199(4.8hex
6. Apparatus
head) or equivalent, M10 × 1.5 × 50.
6.1 Fixture—Aluminum, see Fig. 1.
6.2 Air supply and regulator.
6.3 Polyethylene tubing (or equivalent), polytetrafluoroeth-
Thesolesourceofsupplyoftheblowoutfixturesinbothmaterialsknowntothe
committee at this time is Kovil Manufacturing, 925 Sherman Ave., Hamden, CT
ylene (PTFE) pipe tape, plastic, or brass tube fittings.
06514. If you are aware of alternative suppliers, please provide this information to
6.4 Inline pressure gage or equivalent, 0 to 138 kPa,
ASTM International Headquarters. Your comments will receive careful consider-
ation at a meeting of the responsible technical committee, which you may attend. accurate to 60.7 kPa.
F2523 − 13 (2020)
6.5 Timing device with 1-s increments. 10.4.7 Immediately after assembly (within 2 min of RTV
application)openballvalvetopressurizethesystemquicklyto
6.6 Measuring device, capable of measuring an adhesive
the preset pressure.
bead height of 2 mm.
10.4.8 Start the timer and record the time in seconds at
6.7 Environmentally controlled room (temperature, humid-
whichthesuddenlossofpressureoccurs.Ifnolossofpressure
ity monitoring, and control).
occurs after 1 min, report it as “>60 s.”
10.4.9 Disassembleandcleanthefixturethoroughly,remov-
7. Reagents and Materials
ing all traces of RTV.
7.1 Cleaning Solvent—Appropriate cleaning solvent as
10.4.10 Repeat Steps 10.4.1 to 10.4.9 a second time.
specified by RTV manufacturer.
10.4.11 If the second result is within 610% of the first
result, report the average blowout time to the nearest second.
7.2 Clean, lint-free cloth.
10.4.12 If the second result is in excess of 610% of the
first, repeat until a consistent value is obtained.
8. Conditioning
10.5 Method B—Maximum Blowout Pressure Determina-
8.1 Sample containers shall be allowed to equilibrate to 21
tion:
to 25°C. Time required may vary depending on the size of
container and previous storage conditions. 10.5.1 Method B shall be done at or near maximum
application/flow rate of the sealant.
9. Initial Step 10.5.2 Open exhaust valve to prevent any pretest internal
pressure and close inlet ball valve.
9.1 Connect air supply to regulator and to pressure gage
10.5.3 Apply a continuous 4-mm bead (based on default
usingpolyethylenetubing.Plasticorbrasspressfitfittingsmay
gap, user will have to determine proper bead size for alternate
be used for the connection points, depending on the adaptor
gaps) on the flange of the bottom fixture.
connectiononthethreecomponents.Fittingsthreadsshallhave
10.5.4 Apply the top half of the fixture taking care not to
pipe sealant applied before installing into fixtures.
move the fixture horizontally.
9.2 Connect tube to bottom fixture with a brass fitting
10.5.5 Tighten bolts to 1.0 kg·m 6 10%.
containing pipe sealant applied around threads.
10.5.6 Close exhaust valve.
9.3 Block off open hole of fixture with a properly secured
10.5.7 Screen for approximate blow out pressure by open-
rubber stopper or compress a soft silicone plaque against the
ing the ball valve immediately after assembly (within 2 min of
hole. Check for leaks at the various connection points by
RTV application), so as to increase the pressure by 6.9 kPa
sprayingadiluteliquidsoapandwatersolution whilelooking
every 10 s until blow out occurs. Subsequent iterations to
for air bubbles.
determine blow out pressure may start 6.9 kPa below this
screening pressure. If this screen pressure is at or below 20.7
9.4 Test environment shall be set at 21 to 25°C and 40 6
kPa, the iterations shall use 3.45 kPa increments in this
10% relative humidity.
method; otherwise the increments shall be 6.9 kPa.
10.5.8 Immediately after assembly (within 2 min of RTV
10. Procedure
application), open the ball valve and start incrementally in-
10.1 Use either the default gap of 1 mm or choose a fixture
creasing the pressure every 5 s until the initial pressure of the
with the desired machined gap.
screening pressure minus 6.89 kPa is reached.
10.2 Make sure all traces of cured or uncured RTV from
10.5.9 Start the timer. If no loss of pressure occurs after 1
previous test have been removed.
min, incrementally increase the pressure and start the timer.
10.3 Following the initial setup instructions in Section 9, Repeat this process until failure occurs and record this value.
verify the system is free of leaks. 10.5.10 Disassemble and clean the fixture thoroughly, re-
moving all traces of RTV.
10.4 Method A—Time to Blowout at a Specified Pressure:
10.5.11 Repeatthes
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