Standard Active Last Updated: Feb 25, 2020
ASTM D5421-15

Standard Specification for Contact Molded “Fiberglass” (Glass-Fiber-Reinforced Thermosetting Resin) Flanges


This specification covers the requirements for materials, workmanship, performance, and dimensions of circular contact-molded "fiberglass" (glass fiber reinforced thermosetting resin) flanges for use in pipe systems and tank nozzles. This specification does not address flange design or gasket selection. Flanges may be produced as integral flanges (Type A) or flange-on-pipe (Type B). They may be made of either epoxy resin (Grade 1), polyester resin (Grade 2), phenolic resin (Grade 3), vinylester resin (Grade 4), or furan resin (Grade 5). Flanges are also grouped into classes according to pressure and thrust capability as Class I (hoop and axial pressure) and Class II (hoop pressure only). Specimens shall undergo tests for which performance requirements must be met for sealing, short-term rupture strength, and maximum bolt torque.


1.1 This specification covers circular contact-molded fiberglass reinforced-thermosetting-resin flanges for use in pipe systems and tank nozzles. Included are requirements for materials, workmanship, performance, and dimensions.

1.2 Flanges (see Fig. 1) may be produced as integral flanges, Type A, or flange-on-pipe, Type B.

1.3 This specification is based on flange performance and does not cover design.

1.4 These flanges are designed for use with pipe and tanks that are manufactured to Specifications D2996, D2997, D3262, D3299, D3517, D3754, and D4097.

1.5 Selection of gaskets is not covered in this specification, refer to the manufacturer's recommendation.

1.6 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only.

1.7 The following precautionary caveat pertains only to the test methods portion, Section 9, of this specification: This standard does not purport to address the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Note 1: There is no known ISO equivalent to this standard.

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Book of Standards Volume: 08.03
Developed by Subcommittee: D20.23
Pages: 5
DOI: 10.1520/D5421-15
ICS Code: 23.040.60