What is ASME B16.9 and B16.5? Understanding the Standards for Pipe Fittings and Flanges

In industrial piping systems, precision, reliability, and compatibility are crucial—and that starts with choosing components that comply with international standards. Two of the most widely used specifications in the industry are ASME B16.9 and ASME B16.5, which define the design and dimensions of pipe fittings and flanges, respectively.

As a global supplier of high-quality piping materials, Haihao Group manufactures products strictly according to these standards. Our recent delivery of SS304 butt-weld fittings and weld neck flanges to a domestic client showcases our commitment to standard-compliant production.

Packaged ASME B16.9, ASTM A403, WP304L seamless stainless steel tees and elbows

What Is ASME B16.9?

ASME B16.9 is the American Society of Mechanical Engineers’ standard for factory-made wrought butt-welding fittings. It covers fittings that are used to change the direction, branch, or diameter of a pipeline system.

Common ASME B16.9 Fittings Include:

• 90° and 45° Elbows
• Tees (equal and reducing)
• Reducers (concentric and eccentric)
• Caps
• Crosses

Scope of the Standard:

Applicable to nominal pipe sizes (NPS) from ½” to 48″

Defines wall thickness, center-to-end dimensions, end preparation (bevels), and tolerances

Suitable for welding with carbon steel, stainless steel, alloy steel, and more

Compatible with high-pressure and high-temperature piping systems

ANSI ASME B16.5 class 1500 A350 LF2 weld neck flanges

What Is ASME B16.5?

ASME B16.5 is the standard covering pipe flanges and flanged fittings for sizes from NPS ½” to 24”. It applies to flanges made from forged or cast materials and used in pressure-rated piping systems.

Common Flange Types Under B16.5:

• Weld Neck (WN)
• Slip-On (SO)
• Blind (BL)
• Threaded (THD)
• Socket Weld (SW)
• Lap Joint (LJ)

Key Parameters Defined:

Pressure classes: 150, 300, 600, 900, 1500, and 2500

Facing types: Raised Face (RF), Flat Face (FF), Ring-Type Joint (RTJ)

Bolt circle diameter, number of bolt holes, and thickness

Gasket seating and sealing surfaces

These specifications ensure proper alignment, tightness, and structural performance in demanding pipeline systems.

ASME B16.9 Seamless Concentric Reducers

Haihao Group’s Standard-Compliant Production

In our recent project, Haihao Group produced the following components in full compliance with ASME B16.9 and B16.5:

90° Short Radius Elbows

Equal and Reducing Tees

Concentric Reducers

Weld Neck Flanges (RF)

Material: SS304 stainless steel

Sizes: Multiple, per client specification

All components were manufactured with tight dimensional tolerances and tested for chemical composition and mechanical integrity, ensuring seamless integration in pressurized piping systems.

Why Standards Matter in Piping Systems?

Using ASME-compliant fittings and flanges ensures:

• Compatibility across suppliers and systems
• Safe pressure handling and flow management
• Consistent installation and welding procedures
• Global acceptance and engineering approval

For EPC contractors, end-users, and system integrators, choosing standard-certified components means reducing risk, cost, and installation time.

Choose Haihao Group – Your Trusted ASME B16.9 & B16.5 Supplier

With over 40 years of manufacturing experience and a global client base, Haihao Group is recognized for producing:

• High-quality stainless steel and carbon steel fittings/flanges
• Custom and standard-size components
• Full traceability and material certifications (EN 10204 3.1)
• Support for third-party inspection and special project requirements

Looking for reliable pipe fittings and flanges manufactured to ASME B16.9 and B16.5 standards?

Contact Haihao Group for expert support and competitive quotations. Email:sales@haihaogroup.com