Yuhong Group Co.,Ltd
Yuhong Holding Group Co.,LTD
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ASTM A403 / ASME SA403 WP321H Concentric Reducer, B16.9 Stainless Steel Buttweld Pipe Fittings
ASTM A403 WP321H concentric reducer is a high-performance fitting designed for extreme heat and corrosive environments. Stainless Steel Grade 321H, the "H" suffix (per ASTM A403/A403M) ensures controlled carbon content for elevated temperature service. Titanium binds carbon, preventing chromium carbide precipitation (sensitization) during welding/exposure to 425–815°C. High-Temp Performance: Retains strength and resists oxidation up to 815°C (1500°F). Corrosion Resistance: Resists general corrosion, acids, and chlorides (similar to 304/316).
Material Equivalent of ASTM A403 WP321/321H Stainless Steel Concentric Reducer
| STANDARD | WERKSTOFF NR. | UNS | JIS | EN |
| SS 321 | 1.4541 | S32100 | SUS 321 | X6CrNiTi18-10 |
| SS 321H | 1.4878 | S32109 | SUS 321H | X12CrNiTi18-9 |
Chemical Equation of ASTM A403 WP321/321H Stainless Steel Concentric Reducer
| Grade | C | Mn | Si | P | S | Cr | N | Ni | Ti |
| SS 321 | 0.08 max | 2.0 max | 1.0 max | 0.045 max | 0.030 max | 17.00 - 19.00 | 0.10 max | 9.00 - 12.00 | 5(C+N) - 0.70 max |
| SS 321H | 0.04 - 0.10 | 2.0 max | 1.0 max | 0.045 max | 0.030 max | 17.00 - 19.00 | 0.10 max | 9.00 - 12.00 | 4(C+N) - 0.70 max |
Mechanical Characteristics of ASTM A403 WP321/321H Stainless Steel Concentric Reducer
| Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| 8.0 g/cm3 | 1457 °C (2650 °F) | Psi - 75000 , MPa - 515 | Psi - 30000 , MPa - 205 | 35 % |
Inspection & Testing
PT (Penetrant Testing): Mandatory for detecting surface cracks after forming/welding.
Additional Tests:
PMI (Positive Material Identification): Verifies Ti/Ni/Cr/C content.
Hydrostatic Test: Pressure integrity validation.
Hardness Test: Ensures proper annealing.
Certification: Mill Test Reports (MTRs) confirming compliance with ASTM/ASME.
Application
High-Temperature Systems: power plant boilers, superheaters, steam lines.
Critical Services: Where thermal cycling or weld decay risks exist
PT TEST
The purpose of Penetrant Testing (PT) for steel pipe fittings is to detect surface-breaking discontinuities (defects) that could compromise the fitting's integrity, leading to leaks, failures, or safety hazards. It's a critical non-destructive testing (NDT) method used primarily for quality control and assurance.
