Flange Standards & Specifications
Comprehensive guide to industrial flange standards including ASME, ANSI, AWWA, DIN, API, and MSS specifications
Industrial Flange Standards Overview
Flanges are critical components in piping systems, and their design, dimensions, and material specifications are governed by various international standards. Each standard is developed to address specific industry needs, applications, and geographic requirements. Understanding these standards is essential for proper equipment specification, procurement, and system design.
ASME B16.5
American Society of Mechanical Engineers
Scope
Steel pipe flanges, fittings, valves and flanged unions
Size Range
NPS 1/2 through NPS 24
Pressure Ratings
150, 300, 400, 600, 900, 1500, 2500 PSI
Materials
Applications
- •Petroleum
- •Petrochemicals
- •Power Generation
- + 2 more
ASME B16.47
American Society of Mechanical Engineers
Scope
Large diameter steel flanges (NPS 26 and larger)
Size Range
NPS 26 through NPS 60
Pressure Ratings
Series A (MSS SP-44): 150, 300, 400, 600, 900 | Series B (API 605): 75, 150, 300, 400, 600
Materials
Applications
- •Offshore
- •Pipeline Transport
- •Refining
- + 1 more
AWWA C207
American Water Works Association
Scope
Steel pipe flanges for waterworks (zinc-coated)
Size Range
4 inches through 144 inches
Pressure Ratings
Classes B, D, E, F (different pressure ratings)
Materials
Applications
- •Water Transmission
- •Water Distribution
- •Waterworks Systems
- + 1 more
AWWA C228
American Water Works Association
Scope
Stainless steel pipe flanges for waterworks
Size Range
2 inches through 72 inches
Pressure Ratings
Classes 125, 150, 200 PSI
Materials
Applications
- •Corrosive Water
- •High-Chloride Environments
- •Coastal Systems
- + 1 more
DIN EN 1092-1
Deutsches Institut für Normung / European Standardization
Scope
Metric flanges for industrial applications
Size Range
DN 10 through DN 4000 (metric sizing)
Pressure Ratings
PN 6, PN 10, PN 16, PN 25, PN 40, PN 63, PN 100
Materials
Applications
- •European Industrial
- •ISO Metric Systems
- •Chemical Plants
- + 1 more
API 605
American Petroleum Institute
Scope
Large diameter carbon steel flanges
Size Range
Up to 120 inches OD
Pressure Ratings
150, 300, 600, 900, 1500 PSI classes
Materials
Applications
- •Crude Oil
- •Natural Gas
- •Petrochemical
- + 1 more
MSS SP-44
Manufacturers Standardization Society
Scope
Steel pipeline flanges
Size Range
NPS 1 through NPS 24
Pressure Ratings
Class 150, 300, 600, 900, 1500, 2500
Materials
Applications
- •General Piping
- •Industrial Systems
- •Pressure Equipment
- + 1 more
Why Different Standards?
Different flange standards exist because various industries and regions have unique requirements. Here's a quick overview of the main standard families:
ASME/ANSI Standards
North American standard for industrial flanges
AWWA Standards
Specialized for water and waterworks applications
DIN/EN Standards
Metric-based European and international standards
Key Standards Information
North American Standards
ASME B16.5 & ANSI B16.5
The most widely used flange standard in North America for industrial piping applications. Covers sizes NPS 1/2 through 24 with pressure classes from 150 to 2500 PSI.
ASME B16.47
Covers large diameter flanges (NPS 26 and larger) with lower pressure ratings, commonly used in pipeline and water transmission systems.
API 605
Petroleum Institute standard for large diameter carbon steel flanges, widely used in crude oil and gas transportation systems.
Specialized Standards
AWWA C207 & C228
American Water Works Association standards specifically designed for water and wastewater applications. C207 uses zinc-coated carbon steel; C228 uses stainless steel for corrosive environments.
DIN EN 1092-1
European metric flange standard widely adopted internationally. Uses PN (pressure nominale) ratings from PN6 through PN100, with DN (diamètre nominale) sizing.
MSS SP-44
Manufacturers Standardization Society standard providing specifications for steel pipeline flanges used in general industrial piping systems.
How to Select the Right Standard
Consider These Factors
- 1
Geographic Location
North America typically uses ASME/ANSI standards, while Europe uses DIN/EN standards.
- 2
Industry/Application
Water utilities require AWWA standards; oil/gas industries may use API standards.
- 3
Operating Conditions
Required pressure rating, temperature range, and media compatibility determine standard selection.
- 4
Equipment Compatibility
Flanges must match connected equipment standards and dimension requirements.
- 5
Regulatory Requirements
Some jurisdictions mandate specific standards for safety and compliance.
Quick Selection Guide
Industrial Piping (General)
→ ASME B16.5
Large Diameter Pipelines
→ ASME B16.47 or API 605
Water Systems
→ AWWA C207 (zinc-coated) or C228 (stainless)
European/Metric Systems
→ DIN EN 1092-1
High-Chloride Environments
→ AWWA C228 (stainless steel)
Need Help Selecting the Right Standard?
Our technical experts are ready to guide you through the selection process and ensure you get the perfect flanges for your application.