ASTM A403 WP304H Steel Pipe Fitting

At Haihao Group, we frequently work with austenitic stainless steels specified for high-temperature service, and ASTM A403 WP304H is one of the most requested grades among our industrial clients.

WP304H fittings are essentially based on the well-known 304 stainless steel chemistry, but with a higher carbon content, typically in the range of 0.04–0.10%. This elevated carbon improves the material’s creep strength and structural stability when exposed to prolonged high temperatures, making it a preferred choice for superheater tubes, boiler piping, and other thermal process equipment.

ASTM A403 WP304H Pipe Fitting,90 degree elbows finished in Haihao Group

In our production facility, we manufacture a complete portfolio of stainless steel butt weld fittings in this grade, ensuring compliance with ASME B16.9 dimensional tolerances and ASTM chemical and mechanical property requirements.

Common Types and Dimensions

Our WP304H product range includes:

• 90° and 45° Elbows (Long Radius and Short Radius)
• Tees and Reducing Tees
• Concentric and Eccentric Reducers
• End Caps
• Stub Ends

Depending on project requirements, we supply fittings in seamless or welded construction, with outside diameters ranging from ½ inch up to 48 inches. For all critical orders, each piece is clearly stamped with heat number, grade, size, and schedule to guarantee traceability throughout the supply chain.

Quality Control and Testing

One aspect that sets our production apart is the emphasis on material verification and inspection. For WP304H, this typically includes:

• Positive Material Identification (PMI): to confirm the high carbon content differentiating 304H from standard 304.
• Dimensional inspection: per ASME B16.9 tolerances.
• Hydrostatic testing: as specified by the end user.
• Surface finishing: pickled and passivated for consistent corrosion performance.

In a recent delivery to a refinery project in Northern Europe, we supplied over 800 pieces of 304H elbows and reducers. The fittings underwent 100% PMI, dye penetrant testing on weld seams, and were documented with EN 10204 3.1 certificates.

Advantages of ASTM A403 WP304H

From a design and operations perspective, WP304H offers several benefits:

• Improved strength at elevated temperatures: Suitable for sustained service above 525°C (977°F).
• Good oxidation resistance: Even under cyclic heating conditions.
• Weldability: Similar to standard 304, with attention required to avoid sensitization in the heat-affected zone.
• Corrosion resistance: Comparable to 304 in most media, making it versatile for chemical and thermal process lines.

Typical Applications

Based on the projects we’ve supported, WP304H stainless steel fittings are commonly used in:

• Steam superheater and reheater piping systems.
• Furnace and heat exchanger connections.
• Power plant boiler manifolds.
• Petrochemical process lines with intermittent high temperatures.

Packaging and Traceability

All fittings are cleaned, capped, and securely packed—either in plywood crates or wooden cases, depending on project specifications. Labels are applied for easy identification, and each batch is accompanied by full traceability documentation.

Contact Our Team

If you are considering ASTM A403 WP304H stainless steel pipe fittings for your project, our engineering and production teams can provide detailed support. Whether you need assistance selecting the right schedules, confirming mechanical properties, or arranging third-party inspection, Haihao Group has the experience and capacity to deliver high-quality fittings worldwide.

Email: sales@haihaogroup.com