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ANSI B16.5 Flange Standard Chart | Detailed Class 150–2500 Dimensions

15/04/2026

ANSI B16.5 Flange Standard Chart for Industrial Piping Systems

In industrial piping design and installation, flanges play a critical role in connecting valves, pipes, and equipment. One of the most widely used international standards is ANSI B16.5.

This standard defines the dimensions, pressure ratings, materials, and structural requirements for flanges used in high-pressure industrial systems.

1. What is ANSI B16.5?

ANSI B16.5 (also known as ASME B16.5) is an American standard that specifies requirements for:

Pipe flanges
Gaskets
Bolting
Pressure ratings and nominal sizes

This standard is widely used in:

Oil & gas
Chemical industry
Power plants
Heavy industrial systems

2. ANSI Flange Pressure Classes

ANSI flanges are categorized by pressure ratings (Class):

Class 150
Class 300
Class 600
Class 900
Class 1500
Class 2500

👉 Higher class means higher pressure resistance.

3. ANSI B16.5 Flange Standard Overview Table

Based on Nominal Pipe Size (NPS)

NPS (inch)	DN (mm)	Class 150	Class 300	Class 600	Class 900	Class 1500	Class 2500
1/2”	DN15	✔	✔	✔	✔	✔	✔
1”	DN25	✔	✔	✔	✔	✔	✔
2”	DN50	✔	✔	✔	✔	✔	✔
4”	DN100	✔	✔	✔	✔	✔	✖
8”	DN200	✔	✔	✔	✔	✖	✖

👉 Note: Exact dimensions (OD, bolt circle, bolt holes) vary by pressure class.

4. ANSI Flange Structure

A standard ANSI flange includes:

Outside Diameter (OD)
Bolt Hole Circle
Number of bolt holes
Bore size
Flange thickness

5. Types of ANSI B16.5 Flanges

Weld Neck Flange (WN)
Slip On Flange (SO)
Socket Weld Flange (SW)
Threaded Flange (TH)
Blind Flange (BL)
Lap Joint Flange

6. Applications of ANSI B16.5 Flanges

ANSI standard flanges are widely used in:

Offshore oil & gas systems
Petrochemical plants
Power generation plants
Chemical pipelines
High-pressure steam systems

7. Advantages of ANSI B16.5 Standard

High design accuracy
Excellent pressure resistance
International compatibility and interchangeability
Suitable for heavy industrial systems
Globally recognized standard

8. Important Notes When Selecting ANSI Flanges

Always select correct pressure class according to system requirements
Check material specifications (carbon steel, stainless steel, etc.)
Ensure compatibility with pipes and valves
Consider operating temperature conditions

9. Reliable Supplier of Industrial Flanges & Valves

If you need technical consultation or pricing for ANSI B16.5 flanges, please contact:

Phuc Minh Engineering Co., Ltd
🌐 Website: pm-e.vn
📧 Email: info@pm-e.vn
📱 Hotline: +84 907 450 506 – +84 902 720 814 – +84 979 737 351

👉 We provide:

ANSI, DIN, and JIS flanges
Industrial valves and piping components
Full CO-CQ documentation
Technical support for projects

Conclusion

The ANSI B16.5 standard is one of the most important flange standards in industrial piping systems. Understanding its specifications helps ensure correct equipment selection, system safety, and long-term operational efficiency.

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