Standard Active Last Updated: Dec 08, 2021
ASTM F3525/F3525M-21

Standard Specification Fabricated Fittings of Crosslinkable Polyethylene (CX-PE)

Scope

1.1 This specification establishes requirements for fabricated fittings intended for use with outside-diameter controlled CX-PE pipe and tubing. These fittings are manufactured by heat-fusion joining shape-modified CX-PE components prepared from pipe, molded fittings, sheet, billet, or block. Included are requirements for materials, design, workmanship, minimum dimensions, marking, test methods, and quality control.

1.2 Pressure rating of the fabricated-fitting design is beyond the scope of this standard and shall be established by the fitting manufacturer.

1.3 Fittings manufactured in accordance with this specification are primarily intended to be joined to CX-PE pipes and used in CX-PE piping systems that are commissioned in accordance with a pipe manufacturer recommended commissioning practice. In addition, fittings manufactured in accordance with this specification that are 65 % crosslinked prior to installation can meet the additional requirements of Specification F2829.

1.4 The pressure rating determined for a fitting will result in the fittings’ equivalent dimension ratio (EDR). The EDR specified by the fitting manufacturer is the DR of the piping system for which the fabricated fitting is intended to be joined. This standard specifies that fittings be fabricated from pipe sections of a lower DR than pipe that the fabricated fitting is intended to be joined to. This standard follows the pattern of Specification F2206 which specifies that the wall thickness of fabricated multiple segment elbow fittings shall be a minimum of 22 % more than the pipe to be joined to for example.

Note 1: Increased wall thickness alone is not necessarily sufficient to produce fittings adequate for use. Increased wall thickness without consideration of proper material placement can be detrimental to performance. Finite element analysis studies have shown that abrupt changes in fitting wall sections, such as between a heavy socket hub and body wall, concentrates stress at the transition point. Normal stresses from flex, pressure, expansion, and contraction in a plastic piping system can break a fitting at this point. Short transitions from 22 % thicker fittings to pipe or tubing create a similar condition.

1.5 Design of fabricated fittings is outside of the scope of this standard. Requirements related to thicknesses and taper angles are intended to differentiate potentially good, fabricated fittings from fittings with a high risk of failure. Users of the standard are advised that for large or made-to-order fittings, minimal testing is required by this standard, and it may be insufficient itself to identify improperly designed and produced fittings made in accordance with this standard. The design and production of fittings made in accordance with this standard shall be performed by a fabricator with appropriate training, equipment and knowledge of fitting design and production.

1.6 Pipe used to fabricate fittings in accordance with this specification shall be produced in accordance with pipe manufacturer specifications.

1.7 The text of this specification references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.

1.8 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Non-conformance with this practice is possible if values from the two systems are combined. Values in parentheses are conversions that are appropriately rounded for accuracy and precision; that are not exact equivalents, and that are for non-mandatory informational purposes.

1.9 The following safety hazards caveat pertains only to the pressure test requirements 6.3 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.

1.10 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.

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Details
Book of Standards Volume: 08.05
Developed by Subcommittee: F17.10
Pages: 6
DOI: 10.1520/F3525_F3525M-21
ICS Code: 23.040.40