ASTM A403 WP304
ASTM A403 WP304H Stainless Steel Pipe Fittings
ASTM A403 WP304H Pipe Fittings are high-temperature austenitic stainless steel fittings manufactured from grade 304H — a high-carbon modification of 304 stainless steel. Engineered for enhanced strength at elevated temperatures, WP304H fittings are widely used in boilers, heat exchangers, power generation plants, refining units, and high-temperature fluid processing lines.
With excellent mechanical properties, superior corrosion and oxidation resistance, and outstanding formability, ASTM A403 WP304H is a preferred choice for high-pressure & high-temperature piping systems.
Key Features
High carbon content for improved high-temperature strength
Excellent resistance to oxidation & scaling up to 870°C
Good corrosion resistance in a wide range of environments
Superior weldability and formability
Excellent creep and stress-rupture strength
Ideal for high-temperature & high-pressure fluid transfer
Long service life & durability in harsh industrial conditions
Specifications
| Specification | Details |
|---|---|
| Standard | ASTM A403 |
| Grade | WP304H |
| Material | Austenitic Stainless Steel |
| Manufacturing Types | Seamless / Welded / ERW |
| Sizes | ½” to 48″ (DN15–DN1200) |
| Standards | ASME B16.9 / B16.11 / MSS-SP-43 |
| Pressure Rating | SCH 5S to SCH XXS |
| Forms | Butt-Weld, Socket Weld, Threaded |
| Surface Finish | Mill Finished / Pickled & Passivated |
Equivalent Grades
| Standard | Grade |
|---|---|
| UNS | S30409 |
| WNR | 1.4948 |
| EN | 1.4948 |
| JIS | SUS 304H |
| DIN | X5CrNi18-10 (High-Carbon Variant) |
| BS | 304S51 |
Available Sizes
Butt-Weld Fittings: ½” – 48″
Socket Weld / Threaded Fittings: ⅛” – 4″
Schedules: SCH 5S, 10S, 20, 40, 80, 120, 160, XXS
Custom sizes available on request.
Chemical Composition
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.04 – 0.10 |
| Chromium (Cr) | 18.0 – 20.0 |
| Nickel (Ni) | 8.0 – 11.0 |
| Manganese (Mn) | ≤ 2.0 |
| Silicon (Si) | ≤ 0.75 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa |
| Yield Strength | ≥ 205 MPa |
| Elongation | ≥ 35% |
| Hardness | ≤ 217 HB |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.0 g/cm³ |
| Melting Point | 1400 – 1455°C |
| Thermal Conductivity | 16.2 W/m-K (100°C) |
| Electrical Resistivity | 0.72 µΩ-m (20°C) |
| Modulus of Elasticity | 193 GPa |
Types of ASTM A403 WP304H Fittings
ASTM A403 WP304H Elbow
ASTM A403 WP304H Tee
ASTM A403 WP304H Reducers
ASTM A403 WP304H Caps
ASTM A403 WP304H Cross Fittings
ASTM A403 WP304H Nipples
ASTM A403 WP304H Couplings
ASTM A403 WP304H Stub Ends
Corrosion Resistance
ASTM A403 WP304H provides:
Excellent resistance to atmospheric & oxidizing environments
Good performance in nitric acid & organic chemicals
Resistance to intergranular corrosion due to controlled carbon content
Not recommended for chloride-rich media where 316/316L is preferred
Heat Resistance
Sustains elevated temperatures up to 870°C
Excellent creep and stress-rupture strength
Suitable for continuous service in furnace & boiler environments
Heat Treatment
Solution Annealed: 1040–1100°C followed by water quenching
No hardening by heat treatment (austenitic structure)
Welding
Excellent weldability using TIG/MIG/SMAW
Low-carbon filler recommended to reduce carbide precipitation
Preheat & post-weld heat treatment not required in most cases
Fabrication
Good machinability & formability
Easily cold & hot worked
Recommended to perform pickling & passivation after fabrication
Applications
Petrochemical & Refinery Plants
Thermal & Power Generation Units
Heat Exchangers & Boilers
Super Heaters & Pressure Vessels
High-Temperature Steam & Gas Lines
Chemical Processing Equipment
Oil & Gas Transmission Pipelines
Food & Pharmaceutical Industries