Overview
ISO 7005-1:2011 - "Pipe flanges - Part 1: Steel flanges for industrial and general service piping systems" is an international base specification for steel pipe flanges used across industrial piping systems. It covers flange selection and specification for applications such as chemical plants, power generation, petroleum and natural gas facilities (including LNG and offshore), steam and pressurized water systems, and packaged equipment piping. The standard recognizes two flange series commonly used worldwide and places responsibility for choosing the appropriate flange series and related data with the purchaser.
Key topics and technical requirements
- Flange series and compatibility: Defines two normative series - the PN series (DN size designations) and the class series (NPS/class designations). Mating dimensions are expected to be compatible within the same series, nominal size and rating.
- Purchaser specification data: Requires purchasers to specify series (PN or class), flange rating (PN number or class), size (DN or NPS), material, design pressure and temperature, minimum application temperature, and fluid service category.
- Pressure/temperature limits: References tables of allowable pressure/temperature ratings that depend on flange material and temperature - users must refer to the applicable reference flange standard for exact ratings.
- Materials and process: Specifies that flange materials and manufacturing processes should conform to the chosen series’ reference standard and applicable material requirements.
- Terms, definitions and application considerations: Provides clear definitions (design pressure/temperature, flanged joint, packaged equipment, owner, purchaser, manufacturer, fabricator) and guidance for application, selection and installation.
- Installation guidance and annexes: Includes practical guidance and an informative annex listing purchaser information requirements.
Applications and users
Who uses ISO 7005-1:2011:
- Piping engineers and designers specifying flanged connections in process plants
- Procurement and purchasing teams selecting flange types and materials
- Flange manufacturers and fabricators producing to buyer requirements
- Plant owners, operators and EPC contractors defining installation and material requirements
- Vendors of packaged equipment and skid-mounted assemblies
Practical uses:
- Specifying flange dimensions, materials and pressure/temperature ratings for new installations and replacements
- Ensuring compatibility of flanged components in packaged equipment and plant piping systems
- Aligning purchaser/manufacturer responsibilities during procurement
Related standards
- EN 1092-1 (PN series flanges)
- ANSI/ASME B16.5 (Class series, NPS 1/2–24)
- ANSI/ASME B16.47 (Large diameter class series, NPS 26–60)
Keywords: ISO 7005-1:2011, pipe flanges, steel flanges, PN series, class series, EN 1092-1, ASME B16.5, flange pressure-temperature ratings, piping systems.