Quality Inspection in Action: Haihao Group Ensures Precision and Compliance for SS304 Butt-Weld Fittings and Flanges

At Haihao Group, delivering products that meet both international standards and customer expectations is our top priority. Recently, we conducted a full quality inspection for a domestic client’s order consisting of various stainless steel pipe fittings and flanges, all manufactured in accordance with ASME B16.9 and ASME B16.5 standards. The inspection process highlights our commitment to excellence, precision, and transparency across every stage of production.

ASME B16.5 WN flange dimension inspection

Products Inspected

The batch included a diverse range of stainless steel 304 (SS304) pipe fittings and flanges used in pipeline systems across industries such as oil & gas, petrochemicals, water treatment, and power generation. All products were produced to strict dimensional tolerances and surface finish requirements.

Items under inspection:

• 90° Short Radius Butt-Weld Elbows (ASME B16.9)
• Equal Tees (ASME B16.9)
• Reducing Tees (ASME B16.9)
• Concentric Reducers (ASME B16.9)
• Weld Neck Flanges (WN) (ASME B16.5)
• Material: SS304 stainless steel
• Sizes: Various, customized per order

These components are essential in redirecting flow, connecting pipeline branches, and ensuring pressure continuity in piping systems.

Inspection Scope & Procedures

Haihao Group’s in-house quality control team, supported by customer oversight, conducted a series of inspections focused on dimensional accuracy and chemical composition, two critical factors in ensuring safe installation and long-term performance.

1.Dimensional Inspection

All fittings and flanges were measured using calibrated precision tools to verify compliance with the specified tolerances defined in ASME B16.9 and ASME B16.5:

• Outer Diameter (OD)
• Wall Thickness
• Bore Diameter
• Flange Bolt Hole PCD, Thickness, and Raised Face Height

This guarantees proper alignment, pressure integrity, and compatibility during site installation.

2.Chemical Composition Test

ASME B16.5 WN Flange Chemical Composition Test

Each product was tested to confirm its compliance with SS304 grade requirements, ensuring:

• Cr (Chromium): 18.0–20.0%
• Ni (Nickel): 8.0–11.0%
• Fe (Iron): Balance
• Low content of C, Mn, P, S — within ASTM A403 limits

Using optical emission spectrometry (OES) and portable analyzers, our team validated the raw material consistency, providing peace of mind regarding corrosion resistance and weldability.

Why Quality Inspection Matters

In projects involving pressurized systems, every fitting and flange must meet design tolerances and material standards. Any deviation in chemical composition or size could lead to:

• Joint failure
• Corrosion or cracking
• Increased maintenance cost
• Safety hazards

Through rigorous inspections, Haihao Group ensures that every component shipped meets both functional and regulatory expectations.

Value We Provide

Full traceability and test certificates provided (EN 10204 3.1)

Compliance with international standards (ASME, ASTM, ISO)

Support for third-party or client-supervised inspections

Flexible production for varied sizes and quantities

Haihao Group – Trusted Manufacturer for Stainless Steel Pipe Fittings and Flanges

For over 40 years, Haihao Group has specialized in manufacturing a complete range of welded and seamless pipe fittings, forged flanges, and custom components for industrial piping systems. Our facilities are equipped for precision machining, material testing, and surface finishing, delivering world-class products to clients in over 100 countries.

Contact us today for high-quality ASME B16.9 fittings and B16.5 flanges with full QA documentation and competitive pricing.Email:sales@haihaogroup.com