1、Designation: D 7194 05Standard Specification forAerospace Parts Machined from Polychlorotrifluoroethylene(PCTFE)1This standard is issued under the fixed designation D 7194; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification is intended to be a means of callingout finished machined parts ready for aerospace use. Such pa
3、rtsmay also find use in selected commercial applications wherethere are clear benefits derived from the use of parts withknown or controlled crystallinity, high molecular weight, goodmolecular weight retention, dimensional stability in the fin-ished part, and tightly controlled engineering tolerance
4、s.1.2 This specification establishes requirements for partsmachined from virgin, unplasticized, 100 % polychlorotrifluo-roethylene (PCTFE) homopolymers.1.3 This specification does not cover parts machinedPCTFE copolymers, PCTFE film or tape less than 0.25-mm0.010-in. thick, or modified PCTFE (contai
5、ning pigments orplasticizers).1.4 This specification does not allow parts containing re-cycled material.1.5 This specification classifies parts into three classesbased upon intended uses and exposures: oxygen-containingmedia, reactive media, and inert gases.1.6 ApplicationPCTFE components covered by
6、 thisspecification are virgin, 100 % PCTFE resin, free of plasticiz-ers and other additives. The components are combustionresistant in oxygen, dimensionally stable, and meet otherspecific physical characteristics appropriate for their end use.They are used in valves, regulators, and other devices in
7、oxygen, air, helium, nitrogen, hydrogen, ammonia, and otheraerospace media systems. The components typically are usedas valve seats, o-rings, seals, and gaskets. They are removedand replaced during normal maintenance procedures. Thecomponents provide reliable sealing surfaces resulting inproper clos
8、ure of valves and related devices and no leakagefrom the system into the environment. They will experiencestatic mechanical loading, cyclic mechanical loading, tempera-tures ranging from cryogenic to 71C 160F, and pressures upto 46.2 MPa 6700 psi.1.7 The values stated in SI units are to be regarded
9、asstandard. The values in brackets are for information only.1.8 The following precautionary caveat pertains only to thetest methods portion, Section 12, of this specification: Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibilit
10、y of the userof this standard to establish appropriate safety and healthpractices and to determine the applicability of regulatorylimitations prior to use.NOTE 1There is no equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 621 Test Methods for Deformation of Plastics UnderLoadD 63
11、8 Test Method for Tensile Properties of PlasticsD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 1430 Classification System for Polychlorotrifluoroethyl-ene (PCTFE) PlasticsD 1600 Terminology for Abbreviated Te
12、rms Related toPlasticsD 1708 Test Method for Tensile Properties of Plastics andUse of Microtensile SpecimensD2117 Test Methods for Melting Point of SemicrystallinePolymers by the Hot Stage Microscopy MethodD 2512 Test Method for Compatibility of Materials withLiquid Oxygen (Impact Sensitivity Thresh
13、old and Pass-Fail Techniques)D 4591 Test Method for Determining Temperature andHeats of Transitions of Fluoropolymers by DifferentialScanning CalorimetryG86 Test Method for Determining Ignition Sensitivity ofMaterials to Mechanical Impact in Ambient Liquid Oxy-gen and Pressurized Liquid and Gaseous
14、Oxygen Environ-ments1This specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibility of Subcommittee D20.20 on Plastic Products.Current edition approved July 1, 2005. Published August 2005.2For referenced ASTM standards, visit the ASTM website, www.astm
15、.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 Federa
16、l Standards3NASA-STD-6001 Flammability, Odor, and Offgassing Re-quirements and Test Procedures for Materials in Environ-ments that Support CombustionMechanical Impact forMaterials in Ambient Pressure LOX (Test 13A) andMechanical Impact for Materials in Variable PressureGOX and LOX (Test 13B)3. Termi
17、nology3.1 Definitions: Terms are defined in accordance with Ter-minologies D 883 and D 1600 unless otherwise indicated.3.1.1 air media, nliquid air, pressurized air, and breathingair.3.1.2 cognizant engineering organization, nthe company,agency, or other authority responsible for the system orcompon
18、ent in which aerospace grade PCTFE is used. This, inaddition to design personnel, may include personnel frommaterial and process engineering, or quality groups and othersas appropriate.3.1.3 inert media, ngaseous helium (GHe) and gaseousnitrogen (GN2).3.1.4 oxygen media, nliquid oxygen (LOX) and gas
19、eousoxygen (GOX).3.1.5 reactive media, nammonia (NH3) up to 1.72 MPa250 psig, gaseous hydrogen (GH2) up to 46.2 MPa 6700psig, and liquid hydrogen (LH2) up to 2.76 MPa 400 psig.4. Classification4.1 Part shape and size shall be defined by the applicablepurchase order.4.2 The type of product shall be c
20、ategorized by the intendeduse category:4.2.1 Type I for use in air and oxygen media (see 3.1.1 and3.1.4) at service pressures above 11.4 MPa 1650 psi.4.2.2 Type II for use in air and oxygen media (see 3.1.1 and3.1.4) at service pressures below 11.4 MPa 1650 psi.4.2.3 Type III for use in inert and re
21、active media (see 3.1.3and 3.1.5).4.2.4 Type IV for use in other media specified by thecognizant engineering organization.5. Ordering Information5.1 All parts covered by this specification shall be orderedby Specification D 7194 type as listed in Section 4.6. Materials and Manufacture6.1 Parts shall
22、 be made from polymers meeting all require-ments of Classification System D 1430. Type I, II, III, and IVparts shall be fabricated from polymers classified as meetingClassification System D 1430, Group 01, Class 1, Grade 3.6.2 Parts shall be made from virgin, unplasticized, 100 %polychlorotrifluoroe
23、thylene (PCTFE) homopolymer.6.3 No recycled polymer or regrind shall be permitted.6.4 The base material shall be free of all defects or con-taminants that would be detrimental to final fabrication orperformance of the finished parts.7. Property Requirements7.1 Specification values listed in this spe
24、cification are mini-mum specification values. Any additional requirement forspecific tests or data shall be specified at the time of the order.8. General RequirementsNOTE 2Unless otherwise specified in the purchase contract or order,the molder producing the semifinished article from which finished p
25、artsare made will be responsible for insuring the requirements in 8.10 are met.All other requirements listed in Section 8 pertain to the finished part, andtherefore, will be the responsibility of the supplier of the finished,machined part.8.1 Finished parts shall have a natural translucent appear-an
26、ce. The color shall be white or gray with no yellowing orother unnatural color.8.2 Finished parts shall be free of voids, scratches, fissures,inclusions, or entrapped air bubbles that will affect serviceabil-ity. No particles (for example, black specks) shall be visible tothe naked eye.8.3 All finis
27、hed parts are to be supplied after being annealedin accordance with 12.8.8.4 No dimension of a finished part shall change more than0.003 mm/mm 0.003 in./in. measured at 23 6 2C 73.4 63.6F before and after being held for 48 6 5hat716 5C160 6 9F, as determined by the method in 12.9.8.5 The specific gr
28、avity variation, Dsp. gr. 23/23C forfinished parts when determined by 12.1 shall not exceed 60.01(the weight percent crystallinity, Wc, of a given finished partshall not vary more than 610 %).8.6 The melting point of finished parts shall be determinedto be in the range of 210 to 220C 410 to 428F as
29、determinedby the method in 12.2.8.7 The minimum tensile strength and percent elongation ofthe semifinished article from which the finished part was madeshall be 33.1 MPa 4800 psi and 100 %, respectively, asdetermined by the methods in 12.3.8.8 The maximum allowable deformation under load will be10 %
30、 as determined by the method in 12.4.8.9 Finished parts shall be made from semifinished articleshaving a zero strength time (ZSTstock) of 300 to 450 s (Grade 3)when determined in accordance with 12.5.8.10 The maximum allowable ZST drop, DZST, shall be11.4 1650 oxygen, air yes yesII 11.4 1650 oxygen,
31、 air no noIII all N2, He, H2,ammoniano noIV all other(for example, nitrox)no noAFinished parts made from Type I, II, III, and IV material will be in an annealedcondition, have specific gravity variation no greater than 60.01 g/cm3, have amelting point from 210 to 220C, have a ZSTstockfrom 300 to 450
32、 s, have a ZSTdrop no greater than 20 %, have a deflection under load no greater than 10 %, andhave a minimum tensile strength of 33.1 MPa 4800 psi and a minimum tensileelongation of 100 %.D719405312.6.7 If one sample out of 20 reacts, 40 additional samplesshall be tested without any reactions.12.7
33、Mechanical Impacts/Variable Pressure/GOX or LOX12.7.1 Test Method G86shall be used.12.7.2 Samples shall be prepared in accordance with TestMethod G86.12.7.3 Surface contamination shall be removed by filtered,gaseous nitrogen; or oxygen-compatible solvent, detergent anddistilled water, as appropriate
34、.12.7.4 Pure GOX or LOX shall be used (choice depends onend-use application).12.7.5 Test conditions shall be at the ambient temperature ofthe test facility and a pressure of 11.4 MPa 1650 psi.12.7.6 Twenty separate samples shall be impacted at 98 J72 lbf using a 12.7-mm 12-in. diameter contact.12.7.
35、7 No advance reactions shall be observed. This in-cludes a single audible explosion, visual flash, burning orcharring of samples, or major discoloration.12.7.8 If any sample fails, 40 additional samples shall betested without any reactions.12.8 Annealing12.8.1 Method AFor the best dimensional stabil
36、ity, partsshall be machined to final dimensions with appropriate allow-ances for contraction or expansion during annealing, annealedat 120 6 5C 248 6 9F for 2 h, cooled to room temperature,after which dimensional stability shall be determined (12.9).12.8.2 Method BFor closest tolerances on a finishe
37、d part,parts shall be machined to approximate dimensions, annealedat 120 6 5C 248 6 9F for 2 h, cooled to room temperature,finished to final dimensions, after which dimensional stabilityshall be determined (12.9).12.9 Dimensional Stability12.9.1 Linear dimensional change shall be determined bycompar
38、ing selected dimensions measured before and after ovenheating to simulate accelerated use. Pre- and post-heatingdimensional measurements will be at several reference loca-tions and at multiple locations or both distributed equidistantlyabout the specimen. After the initial dimensions have beenmade a
39、t 20 to 30C 68 to 86F, specimens will be placed inthe preheated oven at 71 6 5C 160 6 9F, heated for 48 65 h, after which the specimens will be removed and allowed tocool. After resting for 16 to 24 h (overnight), the finaldimensions will be measured at 20 to 30C 68 to 86F, andthe percent dimensiona
40、l change, DL, calculated as:DL 5Lf2 LiLi3 100 % (3)where:Liand Lf= initial and final dimensions before and afterheating.12.9.2 Measurement of dimensions will always be madewith respect to a known direction such as the MD, TD, orsealing surface.NOTE 3Conventional metrological methods (coordinate meas
41、uringmachines and dial micrometers) may not have the requisite sensitivity todetect dimensional changes in small parts of the order of 0.3 %. Forexample, a precision micrometer with 0.013-mm 0.0005-in. sensitivitywill not be able to detect dimensional changes smaller than 0.3 % if theoriginal dimens
42、ion is less than 4.3 mm 0.17 in. An example would bePCTFE gaskets with thicknesses of the order of 0.50 mm 0.020 in. Insuch cases, dimensional stability shall be indeterminate and shall notconstitute grounds for nonprocurement.13. Packaging and Package Marking13.1 Finished parts shall be individuall
43、y packaged in sealedenvelopes, pouches, bags, or other containers in accordancewith the manufacturers commercial practice.13.2 Marking for Shipment13.2.1 Each container shall be legibly and permanentlylabeled with the following information:13.2.1.1 MaterialPCTFE parts,13.2.1.2 Type I, II, III, or IV
44、13.2.1.3 Annealing Method: AorB13.2.1.4 ZSTstock13.2.1.5 Specification numberD 719413.2.1.6 Part manufacturers name13.2.1.7 Molders name13.2.1.8 Processing route and date13.2.1.9 Lot number13.2.1.10 Purchase order number13.2.2 For each batch or lot of PCTFE used in oxygen andair media operated at pr
45、essures greater than 11.4 MPa 1650psi (Type I material), a unique dash number or part numbershall be assigned by the part manufacturer to distinguish itfrom like PCTFE parts used 1) in oxygen and air media atpressures less than 11.4 MPa 1650 psi (Type II material), or2) in inert and reactive media (
46、Type III material), or 3) othermedia specified by the cognizant engineering organization(Type IV material).14. Keywords14.1 annealing; dimensional stability; finished parts;PCTFE; polychlorotrifluoroethyleneASTM International takes no position respecting the validity of any patent rights asserted in
47、 connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the re
48、sponsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive care
49、ful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the
