ASTM D7211-23

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Designation: D7211 − 13 (Reapproved 2018) D7211 − 23
Standard Specification for
Parts Machined from Polychlorotrifluoroethylene (PCTFE)
and Intended for General Use
This standard is issued under the fixed designation D7211; 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 Scope*
1.1 This specification is intended to be a means of calling out finished machined parts ready for commercialgeneral use.
1.2 This specification establishes requirements for parts machined from unplasticized, 100 % polychlorotrifluoroethylene
(PCTFE) homopolymers.semifinished parts.
1.3 This specification does not cover parts machined from 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 allows for parts containing regrind and recycled material.
1.5 The specification does not cover PCTFE parts used in aerospace applications involving storage and handling of oxygen media,
air media, inert media, and certain reactive media (specifically ammonia, gaseous hydrogen, and liquid hydrogen), in which
dimensional stability, high molecular weight, molecular weight retention, and crystallinity control are important considerations.
For aerospace grade, machined PCTFE parts, use Specification D7194.
1.3 Application—PCTFE parts covered byFor aerospace grade, machined PCTFE parts, use Specification D7194this specification
are made of 100 % PCTFE resin, free of plasticizers, fillers, or other additives. The parts meet specific physical characteristics
appropriate for their end use, and are typically used in applications requiring good electrical properties or resistance to aggressive
chemical media. General purpose PCTFE parts include seals, gaskets, valve and pump parts (cryogenic and noncryogenic),
translucent tubing, sight glasses, flowmeter tubes, heavy-walled solid pipes and fittings, gears, cams, bearings, laboratory ware,
circuit boards, electrical connector covers and switches, radome covers, and a variety of other stock shapes. They are removed and
replaced during normal maintenance procedures. The parts also experience static or dynamic mechanical loading, and temperatures
ranging from cryogenic to temperatures at or above the glass transition temperature, .T = 55°C (131°F).
g
NOTE 1—Quick-quenched PCTFE will potentially exhibit dimensional relaxation in the vicinity of T . = 55°C (131°F).
g
NOTE 2—Although no recommendations are made regarding the limiting upper use temperature of PCTFE, the heat deflection temperature of PCTFE as
determined by Test Method D648 is 126°C (259°F).
1.4 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only.
This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials.
Current edition approved Nov. 1, 2018May 1, 2023. Published November 2018May 2023. Originally approved in 2005. Last previous edition approved in 20132018 as
D7211 - 13.D7211 - 13(2018). DOI: 10.1520/D7211-13R18.10.1520/D7211-23.
*A Summary of Changes section appears at the end of this standard
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D7211 − 23
1.5 The following precautionary caveat pertains only to the test methods portion, Section 11, 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, health, and environmental practices and determine the applicability of regulatory
limitations prior to use.
NOTE 3—There is no known ISO equivalent to this standard.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D648 Test Method for Deflection Temperature of Plastics Under Flexural Load in the Edgewise Position
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D1430 Classification System for Polychlorotrifluoroethylene (PCTFE) Plastics
D1600 Terminology for Abbreviated Terms Relating to Plastics
D2117 Test Methods for Carbon Black—Surface Area by Nitrogen Adsorption (Withdrawn 1999)
D4591 Test Method for Determining Temperatures and Heats of Transitions of Fluoropolymers by Differential Scanning
Calorimetry
D7194 Specification for Aerospace Parts Machined from Polychlorotrifluoroethylene (PCTFE)
3. Terminology
3.1 Definitions:
3.1.1 Terms are defined in accordance with Terminologies D883 and D1600 unless listed below.
3.1.2 oxygen media, n—liquid oxygen and gaseous oxygen.
3.1.3 air media, n—liquid air and pressurized air (including breathing air).
3.1.4 inert media, n—for example, gaseous helium and gaseous nitrogen.
3.1.5 reactive media, n—for example, ammonia, gaseous hydrogen, and liquid hydrogen, nitrous oxide, and nitrogen trifluoride.
3.1.2 Zero Strength Time (ZST), n—time measured in accordance with Section 10 of Classification D1430 to check the relative
molecular weight of the PCTFE material.
4. Classification
4.1 Part shape and size shall be defined by the applicable purchase order.
4.2 General purpose grade PCTFE shall be Class 1 homopolymer in accordance Classification D1430.
4.3 The grade of product shall be categorized in accordance with Classification D1430 as follows:
4.3.1 Grade 0 having an undetermined or unspecified ZST.
4.3.2 Grade 1 having an as-polymerized ZST of 100 to 199 seconds.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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D7211 − 23
4.3.3 Grade 2 having an as-polymerized ZST of 200 to 299 seconds.
4.3.4 Grade 3 having an as-polymerized ZST of 300 to 450 seconds.
4.4 The finished part shall be received in an unannealed or annealed state as specified in the applicable purchase order. If annealed,
annealing shall be accomplished as described in 11.4.
5. Ordering Information
5.1 All parts covered by this specification shall be ordered by grade and annealed state as listed in Section 4.
6. Materials and Manufacture
6.1 Annealed and unannealed parts shall be made from polymers meeting all requirements of Classification D1430, Group 01,
Class 1, Grades 0, 1, 2, or 3.
6.2 Parts shall be made from virgin, unfilled, unplasticized, 100 % polychlorotrifluoroethylene (PCTFE) homopolymer and up to
30 percent (by volume) regrind or recycled polymer.
6.2 The base material shall be free of all defects or contaminants that would be detrimental to final fabrication or performance of
the finished parts.
7. Property Requirements
7.1 Specification values listed in this specification are minimum specification values or minimum-maximum specification ranges.
Any additional requirement for specific tests or data shall be made at the time of the order.
8. General Requirements
NOTE 4—If so specified in the purchase contract or order, the molder producing the semifinished article from which finished parts are made will be
responsible for insuring the requirement in 8.8 is met. All other requirements listed in this section pertain to the finished part, and therefore, will be the
responsibility of the supplier of the finished, machined part.
8.1 Finished parts shall have a natural translucent appearance. The color shall be white or gray with no yellowing or other
unnatural color.
8.2 Finished parts shall be free of voids, scratches, fissures, inclusions, or entrapped air bubbles that will affect serviceability. No
particles (for example, black specks) shall be visible to the naked eye.
8.3 Depending on commercial resin grade, processing route (for example, extrusion, compression molding, injection molding),
quenching method (water or air cooling), and thickness of the starting semifinished article from which the finished part is made,
the specific gravity, sp. gr. 23/23°C of finished PCTFE parts when determined by 11.1, can vary from 2.11 to 2.17. However, to
ensure consistent properties and performance in the intended application, the specific gravity of a finished part shall not be allowed
to fluctuate freely within the 2.11 to 2.17 range.
8.4 The melting point of finished parts shall be determined to be in the range of 210 to 220°C (410 to 428°F) as determined in
11.2.
8.5 Finished parts shall be made from semifinished articles having an as-molded zero strength time (ZST ) of 300 to 450 s
stock
(Grade 3), or 200 to 299 s (Grade 2), or 100 to 199 s (Grade 1), as determined in 11.3, or shall be undetermined or unspecified
(Grade 0).
NOTE 5—To ensure that the process route does not cause excessive thermal degradation and accompanying molecular weight drop, it is recomme
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