ISO 7005-3:1988

Overview

ISO 7005-3:1988 - "Metallic flanges - Part 3: Copper alloy and composite flanges" defines requirements for circular copper-alloy and composite flanges in Series 1 and Series 2 pressure ratings. The standard covers flange types and facings, dimensions and tolerances, bolting (including copper-alloy bolts), flange face surface finish, marking, inspection and testing, and materials. A non-normative annex gives guidance on application and installation.

Keywords: ISO 7005-3, metallic flanges, copper alloy flanges, composite flanges, flange dimensions, PN ratings, flange facings, surface finish.

Key topics and requirements

• Scope and ratings: Applies to circular flanges for nominal pressures (ISO PN) including PN6, PN10, PN16, PN20, PN25, PN40 and PN50. (The standard maps some American Class ratings to ISO PN, e.g., Class 150 → ISO PN20, Class 300 → ISO PN50.)
• Flange types: Defines common flange types (01, 02, 04, 05, 07, 11, 12, 14, 21) such as plate flanges, loose flanges with collars, welding-neck and slip-on types, hubbed slip-on, and integral flanges.
• Materials: Specifies copper alloys and compatible ferrous backing/clad materials (referenced in tables within the standard). Users should verify national equivalents where applicable.
• Dimensions & tolerances: Provides nominal sizes (DN), mating dimensions, bolt circle, bolt-hole patterns and manufacturing tolerances for each PN and flange type.
• Surface finish & facings: Requires specific flange face finishes (Ra, Rz values) and face types (flat faces for full-face gaskets, raised-face considerations). Surface roughness references and visual/tactile comparison methods are specified.
• Bolting & jointing: Addresses bolt material selection (including copper-alloy bolting per ISO 4281 for temperatures ≤ 120 °C), bolt sizes, washer accommodation, and that joint rating equals the lower of two flange ratings when mismatched.
• Marking & manufacture: Non-integral flanges must be permanently marked with DN, ISO PN, material designation and manufacturer’s name. Etching methods (vibro/electrolytic) recommended; stamping with steel stamps is discouraged for copper-alloy components.
• Inspection & testing: Defines inspection, pressure/temperature (p/T) rating interpretation, and limits for flanges attached by soft solder or silver brazing. Annex covers installation and field testing considerations.

Applications and users

• Practical for designers, piping engineers, procurement specialists, manufacturers and inspectors working with copper-alloy pipe systems, HVAC, marine, refrigeration, potable water and industrial process lines where copper or copper-clad flanges are used.
• Useful when specifying flanges to mate with steel or cast-iron components, ensuring compatibility of PN, DN and flange facing.

Related standards

• ISO 7005 (other parts: Part 1 - steel, Part 2 - cast iron, Part 4 - aluminum)
• ANSI B16.24 (referenced for interchangeability)
• ISO 468 (surface roughness parameters), ISO 7268, ISO 887 (washers), ISO 2016 (socket depths), ISO 4281 (copper-alloy bolting)

This summary helps engineers and specifiers quickly locate the ISO 7005-3 requirements needed for compliant copper-alloy and composite flange selection and installation.