ASTM A403 WP317-S 180 Degree Return Bend SR For Power Generation Heat Exchanger
ASTM A403 WP317-S 180 Degree Return Bend SR For Power Generation Boilers&Heat Exchangers
A403 WP317-S 180° Return Bend is a seamless, butt-weld stainless steel pipe fitting designed to reverse fluid flow by 180° (U-bend shape), fully compliant with ASTM A403/A403M material spec, ASME B16.9 dimensions, and Class S (seamless, no mandatory NDE beyond standard checks) requirements.
1. The material: ASTM A403 WP317-S
(1). Chemical Composition of ASTM A403 WP317
The table below outlines the required chemical composition for WP317 stainless steel.
| Element | Composition (%) |
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.00 max |
| Silicon (Si) | 1.00 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Chromium (Cr) | 18.00 – 20.00 |
| Molybdenum (Mo) | 3.00 – 4.00 |
| Nickel (Ni) | 11.00 – 15.00 |
| Iron (Fe) | Balance (approx. 57.8 min) |
(2). Mechanical Properties of ASTM A403 WP317
| Property | Value |
| Tensile Strength | 515 MPa (min) / 75,000 psi (min) |
| Yield Strength (0.2% Offset) | 205 MPa (min) / 30,000 psi (min) |
| Elongation | 35% (min) -1-2 / 40% (min) -3 |
| Density | 7.9 - 8.0 g/cm³ |
| Melting Point | ~1400 °C (~2550 °F) |
2.180° Return Bend:
U-shaped fitting where two ends are parallel and opposite; available as Long Radius (LR, R=1.5D) or Short Radius (SR, R=1.0D). It replaces two 90° elbows for a compact flow reversal.
3. Key specs & features
- Connection: Butt-weld ends (beveled per ASME B16.25 for full-penetration welding).
- Heat treatment: Solution annealed (typically 1040°C/1900°F followed by water quenching).
- Typical dimensions: NPS ½ to 24 (seamless), schedules 5S, 10S, 40S, 80S, STD, XS, etc.
Main Advantages & Applications of A403 WP317S 180° Return Bend
1. Main Advantages
- Superior corrosion resistance: WP317 has higher Mo (3.0–4.0%) than 316, greatly improving resistance to pitting, crevice corrosion, and chloride stress corrosion — much better than 304/316 in aggressive environments.
- Seamless fitting (ClassS)
- No weld seam inside the fitting
- Stronger, more reliable under pressure
- Lower risk of leakage
- Better surface finish & flow
- 180° flow reversal in one fitting: Replaces two 90° elbows, making layout more compact, cleaner, and cost-effective.
- Butt-weld design: Full penetration welds = strong, permanent, low-maintenance piping system.
- High temperature & pressure capability: Suitable for high-temperature & high-pressure process lines.
2. Primary Applications
- Chemical Processing Industry: For handling corrosive chemicals and acids.
- Power Generation: In boilers, heat exchangers, and high-temperature steam lines.
- Oil & Gas Industry: For piping systems that transport corrosive media or operate under high pressure.
- Heat Exchangers: The 180° return bend is a fundamental component in creating the compact, U-shaped tube bundles found in shell and tube heat exchangers, optimizing space and directing fluid flow.
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