At Haihao Group, we take pride in producing high-quality A105 reducing weld neck flanges, designed for critical piping systems that require smooth flow transitions and reliable sealing. Our forged flanges are engineered to meet ANSI/ASME B16.5 standards, ensuring compatibility and safety in demanding environments.

What is an A105 reducing weld neck flange?

A reducing weld neck flange combines the features of a traditional weld neck flange with an integrated reduction in bore size. This design allows you to connect pipes of different diameters without requiring an additional reducer fitting.

The flange is forged from ASTM A105 carbon steel, a material known for its strength, machinability, and suitability for moderate temperature and pressure applications.

Forged carbon steel reducing weld neck flange machined to ANSI B16.5

Key Features and Benefits

Seamless Flow Transition

The tapered hub and reduced bore enable a smooth flow path, which minimizes turbulence and erosion inside the pipeline.

Robust Connection

Weld neck flanges are butt-welded to the pipe, providing exceptional structural integrity and reducing the risk of leakage under pressure.

Forged Material Quality

Each flange is produced from A105 forged steel with a fine-grain microstructure, improving toughness and performance under load.

Dimensional Accuracy

Our reducing weld neck flanges are precision-machined to strict tolerances in accordance with ASME B16.5, covering sizes, facing types, and pressure ratings (Class 150 to Class 600 and beyond).

Applications

These flanges are commonly used in:

• Petrochemical pipelines
• Oil & gas processing facilities
• Power generation plants
• Water treatment systems

The ability to directly connect pipes of varying diameters helps reduce installation complexity and save space in compact layouts.

Manufacturing Process and Quality Control

At Haihao Group, our production follows a controlled workflow:

Material Selection

Every flange begins with A105 billet, heat-certified to ensure compliance with mechanical and chemical requirements.

Forging and Heat Treatment

Billets are heated and forged into shape, then normalized to achieve the desired mechanical properties.

Machining

We machine the flange faces and bores to tight dimensional tolerances, verifying compatibility with mating pipe ends.

Inspection

Before shipment, each flange undergoes thorough visual and dimensional inspection. We confirm:

No rust or corrosion

No scratches, dents, or warping

Accurate sealing face smoothness (raised face or RTJ as specified)

Certification

All flanges are supplied with:

• Material Test Certificates (EN 10204 3.1 or 3.2)
• Dimensional reports
• Optional NACE compliance for sour service

Packaging and Delivery

To protect the flanges during transit, we:

• Apply rust-preventive oil to machined surfaces
• Fit protective caps over the sealing face
• Wrap each unit in moisture-resistant film
• Pack them securely in sturdy wooden crates

This ensures your products arrive in perfect condition, ready for installation.

Why Choose Haihao Group?

For more than 40 years, Haihao has been manufacturing carbon steel pipe flanges and fittings for global customers. When you work with us, you can expect:

✔ Consistent quality
✔ Complete documentation
✔ Competitive pricing
✔ Flexible production for custom sizes

Our A105 reducing weld neck flanges are trusted by EPC contractors and fabricators in over 80 countries.

FAQs

Q: What pressure ratings are available?
A: We can produce Class 150, 300, 600, and higher ratings on request.

Q: Do you offer RTJ facings?
A: Yes, in addition to raised face (RF), we can provide ring-type joint (RTJ) facing for higher-pressure applications.

Q: Can you customize the bore dimensions?
A: Absolutely. We can tailor the bore and reduction sizes to match your pipe schedule and project specifications.

Q: Do the flanges comply with NACE MR0175?
A: NACE compliance can be provided upon request, with proper material certification.

Hebei haihao flange factory can design and produce the reducing flange as per request , we can supply the reducing flange in various types including weld-neck reducing flange, slip on reducing flange, threaded reducing flange and plain reducing flange etc. Using the reducing flange could decrease the cost of transitions between different pipe sizes.

Difference between weld neck flange and slip on flange

The difference between threaded flanges and weld neck flanges