ISO 7005-2:1988

Overview

ISO 7005-2:1988 - Metallic flanges - Part 2: Cast iron flanges - specifies requirements for circular grey, malleable and ductile cast iron flanges. Together with ISO 7005-1 and ISO 7005-3 it replaces older national standards (ISO 2084, ISO 2229, ISO 2441). The standard defines flange types, facings, dimensions, materials and pressure/temperature (p/T) ratings for a single international flange system (series 1 and 2), plus marking, inspection and testing guidance. Annex A gives guidance on dimensional tolerances and Annex B is a bibliography.

Keywords: ISO 7005-2, cast iron flanges, metallic flanges, PN ratings, DN, pressure/temperature.

Key topics and technical requirements

• Scope and materials
  • Covers flanges manufactured from grey, malleable and ductile cast iron (material designations referenced in the document).
  • Materials and corresponding p/T ratings are listed in designated tables (material table and p/T rating tables).
• Pressure/Temperature (p/T) ratings
  • Defines nominal pressure ratings (ISO PN) used instead of US “Class” designations (e.g., PN20 and PN50 used to represent certain ANSI classes).
  • Ratings are maximum allowable non-shock working pressures at specified temperatures; lower flange rating governs a joint.
• Flange types and facings
  • Specifies common flange types (welding neck, slip-on, socket-weld, threaded, loose hubbed, blank, integral, etc.).
  • Two facing types are defined: flat face (type A) and raised face (type B), with raised-face dimensions given.
• Dimensions and tolerances
  • Dimensional tables define nominal sizes (DN), bolt patterns, and flange dimensions for each PN rating. Annex A provides guidance on tolerances.
• Jointing, bolting and surface finish
  • Guidance on gasket use, bolting selection and recommendations for mating flange faces. Surface finish requirements for flange faces are specified and referenced against standard roughness parameters.
• Marking, inspection and repairs
  • Mandatory marking (DN, PN, material designation, manufacturer) and guidance on inspection/testing. Welding repairs for ductile cast iron allowed when procedures are established.

Practical applications

• Use for design, manufacture, procurement and inspection of cast iron flanges in piping systems, fittings and pressure-retaining equipment.
• Applicable across industries using cast-iron flange connections where standardization of dimensions, p/T ratings and interchangeability is required (waterworks, process piping, valves and fittings).
• Helps ensure interoperability: PN20 and PN50 cast iron flanges are intended to be interchangeable with corresponding ANSI B16.1/B16.42 products where noted.

Who should use this standard

• Flange and pipe manufacturers, foundries and component suppliers
• Mechanical and piping engineers, designers and specifiers
• Procurement teams and quality/inspection personnel
• Standards committees and regulatory bodies

Related standards

• ISO 7005-1 (Steel flanges), ISO 7005-3 (Copper alloy/composite flanges), ISO 7005-4 (Aluminium flanges)
• Referenced material and component standards (listed within ISO 7005-2) and ANSI standards for compatibility notes (ANSI B16.1, ANSI B16.42).