ASTM F2523-07(2013)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F2523 − 07(Reapproved 2013)
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 3.2.2 T–joint, n—interface created in a sealing surface
where three structural components meet.
1.1 Thispracticeprovidesameanstodeterminetheblowout
3.2.2.1 Discussion—This interface may exist as a small gap
resistance of a room-temperature vulcanized elastomer system
requiring a material such as room-temperature vulcanized
(RTV) using a standard fixture.
elastomer (RTV) to seal.
1.2 The values stated in SI units are to be regarded as
3.3 Acronyms:
standard. No other units of measurement are included in this
3.3.1 RTV—room-temperature vulcanized elastomer
standard.
1.3 This standard does not purport to address all of the
4. Summary of Practice
safety concerns, if any, associated with its use. It is the
4.1 Condensation cures RTVs as a one-component system
responsibility of the user of this standard to establish appro-
cure when exposed to moisture in the ambient air or as
priate safety and health practices and determine the applica-
two-component systems when those components are mixed
bility of regulatory limitations prior to use.
together.RTVsareoftenusedtosealjointswherethreeflanges
meet (T joints) such as an automotive engine’s front cover,
2. Referenced Documents
engineblock,andoilpan.Becauseofmachiningandassembly
2.1 ASTM Standards:
tolerance variations, theseTjoints may have a slight misalign-
D907Terminology of Adhesives
ment or gap.We also find gaps in the half-round area of the oil
D1566Terminology Relating to Rubber
pantoblockandinthevalleybetweentheintakemanifoldand
F2468Classification for Specifying Silicone Adhesives and
block on certain V-engines as a result of manufacturing
Sealants for Transportation Applications
tolerances.TheRTVisusedtosealinfluids.Insomeassembly
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
3. Terminology pressure.
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
3.2 Definitions of Terms Specific to This Standard:
system gap (default gap is 1mm), while the bottom half
3.2.1 blowout, n—disruption of the uncured RTV integrity
provides the mating flange and the connection for the pressure
inajointfromsystempressurizationresultinginsuddenlossof
input. The gap is machined into the top half of the fixture in a
pressure.
“pie slice” 60° angle.Acontinuous bead of RTV is applied to
theentirebottomportionofthefixture,thetophalfiscarefully
attached, and the fixture is pressurized to the prescribed limits
ThispracticeisunderthejurisdictionofASTMCommitteeF03onGasketsand
and held for a specified time period. If the RTV is not capable
is the direct responsibility of Subcommittee F03.70 on Formed in Place Gaskets.
Current edition approved May 1, 2013. Published May 2013. Originally
ofsealingatthepressureapplied,asuddenlossofpressurewill
ε1
approved in 2005. Last previous edition approved in 2007 as F2523–07 . DOI:
occur.
10.1520/F2523-07R13.
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
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Available from Society of Automotive Engineers (SAE), 400 Commonwealth
Dr., Warrendale, PA 15096-0001.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2523 − 07 (2013)
5. Significance and Use 9.3 Block off open hole of fixture with a properly secured
rubber stopper or compress a soft silicone plaque against the
5.1 This practice may be used to determine the viability of
hole. Check for leaks at the various connection points by
an RTV sealant to withstand pressure leak testing before cure
sprayingadiluteliquidsoapandwatersolution whilelooking
at maximum gap conditions of a system. This practice may be
for air bubbles.
usedtoindicateanRTV’sacceptabilitytoundergoanassembly
line leak check without causing a leak path due to material 9.4 Test environment shall be set at 21 to 25°C and 40 6
blow out. 10% relative humidity.
10. Procedure
6. Apparatus
10.1 Use either the default gap of 1 mm or choose a fixture
6.1 Fixture—Aluminum, see Fig. 1.
with the desired machined gap.
6.1.1 Aluminum casting, forging, or bar stock with 60
Brinell hardness, minimum.
10.2 Make sure all traces of cured or uncured RTV from
6.1.2 Surfacefinishshallbeintherangeof0.7to3.2µm Ra.
previous test have been removed.
6.1.3 Top half of fixture shall have a machined cutout to the
10.3 Following the initial setup instructions in Section 9,
desired gap depth (1.0 6 0.025 mm default gap), per Fig. 1.
verify the system is free of leaks.
Thegapandflangewidtharecriticaldimensionsandshouldbe
10.4 Method A—Time to Blowout at a Specified Pressure:
controlled to a tight tolerance (62.5% is recommended). All
10.4.1 Preset pressure regulator to the applicable test pres-
other dimensions are allowed 610 %.
sure.
6.1.4 Fournut,bolt,andwashersetsperSAEJ1199(4.8hex
10.4.2 Open exhaust valve to prevent any pretest internal
head) or equivalent, M10 × 1.5 × 50.
pressure and close inlet ball valve.
6.2 Air supply and regulator.
10.4.3 Apply a continuous 4-mm bead (based on default
6.3 Polyethylene tubing (or equivalent), polytetrafluoroeth-
gap, user will have to determine proper bead size for alternate
ylene (PTFE) pipe tape, plastic, or brass tube fittings.
gaps) on the flange of the bottom fixture.
10.4.4 Apply the top half of the fixture, taking care not to
6.4 Inline pressure gage or equivalent, 0 to 138 kPa,
move the fixture horizontally.
accurate to 60.7 kPa.
10.4.5 Tighten bolts to 1.0 kg·m 6 10%.
6.5 Timing device with 1-s increments.
10.4.6 Close exhaust valve.
6.6 Measuring device, capable of measuring an adhesive
10.4.7 Immediately after assembly (within 2 min of RTV
bead height of 2 mm.
application)openballvalvetopressurizethesystemquicklyto
the preset pressure.
6.7 Environmentally controlled room (temperature, humid-
10.4.8 Start the timer and record the time in seconds at
ity monitoring, and control).
whichthesuddenlossofpressureoccurs.Ifnolossofpressure
occurs after 1 min, report it as “>60 s.”
7. Reagents and Materials
10.4.9 Disassembleandcleanthefixturethoroughly,remov-
7.1 Cleaning Solvent—Appropriate cleaning solvent as
ing all traces of RTV.
specified by RTV manufacturer.
10.4.10 Repeat Steps 10.4.1 to 10.4.9 a second time.
7.2 Clean, lint-free cloth.
10.4.11 If the second result is within 610% of the first
result, report the average blowout time to the nearest second.
8. Conditioning
10.4.12 If the second result is in excess of 610% of the
8.1 Sample containers shall be allowed to equilibrate to 21 first, repeat until a consistent value is obtained.
to 25°C. Time required may vary depending on the size of
10.5 Method B—Maximum Blowout Pressure Determina-
container and previous storage conditions.
tion:
10.5.1 Method B shall be done at or near maximum
9. Initial Step
application/flow rate of the sealant.
9.1 Connect air supply to regulator and to pressure gage
10.5.2 Open exhaust valve to prevent any pretest internal
usingpolyethylenetubing.Plasticorbrasspressfitfittingsmay
pressure and close inlet ball valve.
be used for the connection points, depending on the adaptor
10.5.3 Apply a continuous 4-mm bead (based on default
connectiononthethreecomponents.Fittingsthreadsshallhave
gap, user will have to determine proper bead size for alternate
pipe sealant applied before installing into fixtures.
gaps) on the flange of the bottom fixture.
10.5.4 Apply the top half of the fixture taking care not to
9.2 Connect tube to bottom fixture with a brass fitting
move the fixture horizontally.
containing pipe sealant applied around threads.
10.5.5 Tighten bolts to 1.0 kg·m 6 10%.
10.5.6 Close exhaust valve.
Thesolesourceofsupplyoftheblowoutfixturesinbothmaterialsknowntothe 10.5.7 Screen for approximate blow out pressure by open-
committee at this time is Kovil Manufacturing, 925 Sherman Ave., Hamden, CT
ing the ball valve immediately after assembly (within 2 min of
06514. If you are aware of alternative suppliers, please provide this information to
ASTM International Headquarters. Your comments will receive careful consider-
1 5
ation at a meeting of the responsible technical committee, which you may attend. Commercially available products exist from a wide variety of distributors.
F2523 − 07 (2013)
NOTE 1—Torque sequence shall be “crisscross” pattern.
FIG. 1 Aluminum Blowout Fixtures
RTV application), so as to increase the pressure by 6.9 kPa kPa, the iterations shall use 3.45 kPa increments in this
every 10 s until blow out occurs. Subsequent iterations to
method; otherwise the increments shall be 6.9 kPa.
determine blow out pressure may start 6.9 kPa below this
screening pressure. If this screen pressure is at or below 20.7
F2523 − 07 (2013)
10.5.8 Immediately after assembly (within 2 min of RTV shimming of the fixture which may result in a
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