ASTM D7194-05
(Specification)Standard Specification for Aerospace Parts Machined from Polychlorotrifluoroethylene
Standard Specification for Aerospace Parts Machined from Polychlorotrifluoroethylene
ABSTRACT
This specification establishes the requirements for parts intended for aerospace use and machined from polychlorotrifluoroethylene (PCTFE) homopolymers. This specification, however, does not cover parts machined from PCTFE copolymer, PCTFE film or tape, or modified PCTFE. Material covered by this specification is on four types, differentiated based on intended uses and exposures: Types I (high service pressure) and II (low service pressure) for use in air and oxygen media, Type II for use in inert and reactive media, and Type IV for use in other media. The parts shall be manufactured from virgin, unplasticized, pure PCTFE homopolymer, and the use of recycled polymer or regrind shall be prohibited. The base material shall be free of defects and contaminants. The finished parts shall be white or gray in color with a natural translucent appearance, and shall be free of voids, scratches, fissures, inclusions, or entrapped air bubbles. Tests for specific gravity, melting point, tensile strength and elongation, deformation under load, zero strength time, mechanical impact (in ambient liquid oxygen and pressurized liquid and gaseous oxygen environments), and dimensional stability shall be performed and shall conform to the requirements specified.
SCOPE
1.1 This specification is intended to be a means of calling out finished machined parts ready for aerospace use. Such parts may also find use in selected commercial applications where there are clear benefits derived from the use of parts with known or controlled crystallinity, high molecular weight, good molecular weight retention, dimensional stability in the finished part, and tightly controlled engineering tolerances.
1.2 This specification establishes requirements for parts machined from virgin, unplasticized, 100 % polychlorotrifluoroethylene (PCTFE) homopolymers.
1.3 This specification does not cover parts machined PCTFE copolymers, PCTFE film or tape less than 0.25-mm [0.010-in.] thick, or modified PCTFE (containing pigments or plasticizers).
1.4 This specification does not allow parts containing recycled material.
1.5 This specification classifies parts into three classes based upon intended uses and exposures: oxygen-containing media, reactive media, and inert gases.
1.6 Application PCTFE components covered by this specification are virgin, 100 % PCTFE resin, free of plasticizers and other additives. The components are combustion resistant in oxygen, dimensionally stable, and meet other specific physical characteristics appropriate for their end use. They are used in valves, regulators, and other devices in oxygen, air, helium, nitrogen, hydrogen, ammonia, and other aerospace media systems. The components typically are used as valve seats, o-rings, seals, and gaskets. They are removed and replaced during normal maintenance procedures. The components provide reliable sealing surfaces resulting in proper closure of valves and related devices and no leakage from the system into the environment. They will experience static mechanical loading, cyclic mechanical loading, temperatures ranging from cryogenic to 71°C [160°F], and pressures up to 46.2 MPa [6700 psi].
1.7 The values stated in SI units are to be regarded as standard. The values in brackets are for information only.
1.8 The following precautionary caveat pertains only to the test methods portion, Section 12 of this specification: 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 to determine the applicability of regulatory limitations prior to use.
Note 1—There is no equivalent ISO standard.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D7194 −05
StandardSpecification for
Aerospace Parts Machined from Polychlorotrifluoroethylene
(PCTFE)
This standard is issued under the fixed designation D7194; 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.
1. Scope 1.7 The values stated in SI units are to be regarded as
standard. The values in parentheses are for information only.
1.1 This specification is intended to be a means of calling
outfinishedmachinedpartsreadyforaerospaceuse.Suchparts
1.8 The following precautionary caveat pertains only to the
may also find use in selected commercial applications where
test methods portion, Section 12, of this specification: This
there are clear benefits derived from the use of parts with
standard does not purport to address all of the safety concerns,
known or controlled crystallinity, high molecular weight, good
if any, associated with its use. It is the responsibility of the user
molecular weight retention, dimensional stability in the fin-
of this standard to establish appropriate safety and health
ished part, and tightly controlled engineering tolerances.
practices and to determine the applicability of regulatory
1.2 This specification establishes requirements for parts
limitations prior to use.
machined from virgin, unplasticized, 100 % polychlorotrifluo-
NOTE 1—There is no known ISO equivalent to this standard.
roethylene (PCTFE) homopolymers.
1.3 This specification does not cover parts machined
2. Referenced Documents
PCTFE copolymers, PCTFE film or tape less than 0.25-mm
(0.010-in.) thick, or modified PCTFE (containing pigments or 2.1 ASTM Standards:
plasticizers).
D621 Specification for Jute Rove and Plied Yarn for Elec-
trical and Packing Purposes (Withdrawn 2000)
1.4 This specification does not allow parts containing re-
D638 Test Method for Tensile Properties of Plastics
cycled material.
D792 Test Methods for Density and Specific Gravity (Rela-
1.5 This specification classifies parts into three classes
tive Density) of Plastics by Displacement
based upon intended uses and exposures: oxygen-containing
D883 Terminology Relating to Plastics
media, reactive media, and inert gases.
D1430 ClassificationSystemforPolychlorotrifluoroethylene
1.6 Application—PCTFEcomponentscoveredbythisspeci-
(PCTFE) Plastics
fication are virgin, 100 % PCTFE resin, free of plasticizers and
D1600 Terminology forAbbreviatedTerms Relating to Plas-
other additives. The components are combustion resistant in
tics
oxygen, dimensionally stable, and meet other specific physical
D1708 Test Method forTensile Properties of Plastics by Use
characteristics appropriate for their end use. They are used in
of Microtensile Specimens
valves, regulators, and other devices in oxygen, air, helium,
D2117 Test Methods for Carbon Black—Surface Area by
nitrogen, hydrogen, ammonia, and other aerospace media
Nitrogen Adsorption (Withdrawn 1999)
systems. The components typically are used as valve seats,
D2512 Test Method for Compatibility of Materials with
o-rings, seals, and gaskets. They are removed and replaced
Liquid Oxygen (Impact Sensitivity Threshold and Pass-
during normal maintenance procedures. The components pro-
Fail Techniques)
vide reliable sealing surfaces resulting in proper closure of
D4591 Test Method for Determining Temperatures and
valves and related devices and no leakage from the system into
Heats of Transitions of Fluoropolymers by Differential
the environment. They will experience static mechanical
Scanning Calorimetry
loading, cyclic mechanical loading, temperatures ranging from
cryogenicto71ºC(160ºF),andpressuresupto46.2MPa(6700
psi).
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This specification is under the jurisdiction of ASTM Committee D20 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Standards volume information, refer to the standard’s Document Summary page on
Materials. the ASTM website.
Current edition approved July 1, 2005. Published August 2005. DOI: 10.1520/ The last approved version of this historical standard is referenced on
D7194-05. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7194−05
G86 Test Method for Determining Ignition Sensitivity of parts shall be fabricated from polymers classified as meeting
Materials to Mechanical Impact in Ambient Liquid Oxy- Classification System D1430, Group 01, Class 1, Grade 3.
gen and Pressurized Liquid and Gaseous Oxygen Envi-
6.2 Parts shall be made from virgin, unplasticized, 100 %
ronments
polychlorotrifluoroethylene (PCTFE) homopolymer.
2.2 Federal Standards
6.3 No recycled polymer or regrind shall be permitted.
NASA-STD-6001 Flammability, Odor, and Offgassing Re-
6.4 The base material shall be free of all defects or con-
quirements and Test Procedures for Materials in Environ-
taminants that would be detrimental to final fabrication or
ments that Support Combustion—Mechanical Impact for
performance of the finished parts.
Materials in Ambient Pressure LOX (Test 13A) and
Mechanical Impact for Materials in Variable Pressure
7. Property Requirements
GOX and LOX (Test 13B)
7.1 Specification values listed in this specification are mini-
3. Terminology mum specification values. Any additional requirement for
specific tests or data shall be specified at the time of the order.
3.1 Definitions:
3.1.1 Terms are defined in accordance with Terminologies
8. General Requirements
D883 and D1600 unless otherwise indicated.
NOTE 2—Unless otherwise specified in the purchase contract or order,
the molder producing the semifinished article from which finished parts
3.1.2 air media, n—liquid air, pressurized air, and breathing
aremadewillberesponsibleforinsuringtherequirementsin8.10aremet.
air.
All other requirements listed in Section 8 pertain to the finished part, and
3.1.3 cognizant engineering organization, n—the company,
therefore, will be the responsibility of the supplier of the finished,
agency, or other authority responsible for the system or machined part.
component in which aerospace grade PCTFE is used. This, in
8.1 Finished parts shall have a natural translucent appear-
addition to design personnel, may include personnel from
ance. The color shall be white or gray with no yellowing or
material and process engineering, or quality groups and others
other unnatural color.
as appropriate.
8.2 Finished parts shall be free of voids, scratches, fissures,
3.1.4 inert media, n—gaseous helium (GHe) and gaseous
inclusions, or entrapped air bubbles that will affect serviceabil-
nitrogen (GN ).
ity. No particles (for example, black specks) shall be visible to
3.1.5 oxygen media, n—liquid oxygen (LOX) and gaseous
the naked eye.
oxygen (GOX).
8.3 All finished parts are to be supplied after being annealed
3.1.6 reactive media, n—ammonia (NH ) up to 1.72 MPa
in accordance with 12.8.
(250 psig), gaseous hydrogen (GH ) up to 46.2 MPa (6700
8.4 No dimension of a finished part shall change more than
psig), and liquid hydrogen (LH ) up to 2.76 MPa (400 psig).
0.003 mm/mm (0.003 in./in.) measured at 23 6 2ºC (73.4 6
3.6ºF) before and after being held for 48 65hat71 6 5ºC
4. Classification
(160 6 9ºF), as determined by the method in 12.9.
4.1 Part shape and size shall be defined by the applicable
8.5 The specific gravity variation, ∆sp. gr. 23/23ºC for
purchase order.
finished parts when determined by12.1 shall not exceed 60.01
c
4.2 The type of product shall be categorized by the intended
(the weight percent crystallinity, W , of a given finished part
use category:
shall not vary more than 610 %).
4.2.1 Type I for use in air and oxygen media (see 3.1.2 and
8.6 The melting point of finished parts shall be determined
3.1.5) at service pressures above 11.4 MPa (1650 psi).
tobeintherangeof210to220ºC(410to428ºF)asdetermined
4.2.2 Type II for use in air and oxygen media (see 3.1.2 and
by the method in 12.2.
3.1.5) at service pressures below 11.4 MPa (1650 psi).
4.2.3 Type III for use in inert and reactive media (see 3.1.4 8.7 The minimum tensile strength and percent elongation of
and 3.1.6). the semifinished article from which the finished part was made
4.2.4 Type IV for use in other media specified by the
shall be 33.1 MPa (4800 psi) and 100 %, respectively, as
cognizant engineering organization. determined by the methods in 12.3.
8.8 Themaximumallowabledeformationunderloadwillbe
5. Ordering Information
10 % as determined by the method in 12.4.
5.1 All parts covered by this specification shall be ordered
8.9 Finished parts shall be made from semifinished articles
by Specification D7194 type as listed in Section 4.
havingazerostrengthtime(ZST )of300to450s(Grade3)
stock
when determined in accordance with 12.5.
6. Materials and Manufacture
8.10 The maximum allowable ZST drop, ∆ZST, shall be
6.1 Parts shall be made from polymers meeting all require-
<20 % as determined in 12.5.4.
ments of Classification System D1430. Type I, II, III, and IV
9. Specific Requirements
9.1 Specific requirements for Type I, II, III, and IV material
Available from the U.S. Government Printing Office, Superintendent of
Documents, 732 N. Capitol St., NW, Mail Stop: DE, Washington, DC 20401. are summarized in Table 1.
D7194−05
A
TABLE 1 Type I, II, III, and IV Material Requirements
ρ ρ 2ρ
c a
c
W 5 3100% (1)
S D
Type Service Media Mechanical Assign Unique
ρ ρ 2ρ
c a
Pressure Impact Test Part
(MPa (psi)) Required Number or
Dash
ρ 5
c 24 27 2
0.4556310.8079 310 T10.874 310 T
Number for the
Finished Part
I >11.4 (1650) oxygen, air yes yes
ρ 5
II < 11.4 (1650) oxygen, air no no
24 27 2
a
0.4788411.186 310 T12.20 310 T
III all N , He, H , no no
2 2
ammonia
Where:
IV all other no no
(for example,
ρ = density (specific gravity) of the finished part,
–3
nitrox)
ρ = densityofpureamorphousphase(ρ =2.0760gcm at
a a
A
Finished parts made from Type I, II, III, and IV material will be in an annealed
23ºC),
–3
condition, have specific gravity variation no greater than ±0.01 g/cm , have a –3
ρ = densityofthepurecrystallinephase(ρ =2.1856gcm
c c
melting point from 210 to 220ºC, have a ZST from 300 to 450 s, have a ZST
stock
at 23ºC), and
dropnogreaterthan20 %,haveadeflectionunderloadnogreaterthan10 %,and
have a min
...
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