321 Stainless Steel Fittings – Titanium-Stabilised High-Temperature Champions for 870 °C Welded Systems
When your piping assembly must survive continuous exposure between 425 °C and 850 °C, only 321 Stainless Steel Fittings eliminate the risk of sensitisation and intergranular corrosion. The deliberate addition of titanium (≥5×C) locks up carbon as harmless TiC, preventing chromium depletion along grain boundaries during welding or long-term thermal cycling. This unique mechanism delivers full corrosion resistance after welding, excellent creep strength to 870 °C, and complete compatibility with standard welding procedures—making 321 Stainless Steel Fittings the undisputed standard for aircraft exhaust manifolds, furnace ducting, thermal oxidizers, and petrochemical flare lines worldwide.
321 Stainless Steel Pipe Fittings – Seamless Butt-Weld Fittings – ASTM A403 WP321/321H, Ready for High-Temperature Service
Key Features & Benefits
- Titanium stabilised (Ti ≥ 5×C) – immunity to sensitisation 425–850 °C
- Continuous service to 870 °C; intermittent to 900 °C with minimal scaling
- Excellent creep & stress-rupture strength above 600 °C
- Superior weldability – no post-weld stabilising heat treatment required for most services
- Fully austenitic – non-magnetic, even after heavy cold forming
- Available in both standard and aerospace-special 321 stainless steel pipe fitting configurations
- Full compliance – ASTM A182, A403 WP321/321H, ASME B16.9, B16.11, EN 1.4541, PED 2014/68/EU
Technical Specifications
Table 1 – Chemical Composition (ASTM A403)
| Element | 321 % | 321H % | 304 % | 316 % |
|---|---|---|---|---|
| Cr | 17.0–19.0 | 17.0–19.0 | 18.0–20.0 | 16.0–18.0 |
| Ni | 9.0–12.0 | 9.0–12.0 | 8.0–10.5 | 10.0–14.0 |
| Ti | ≥5×C | ≥4×C | 0 | 0 |
| Mo | 0 | 0 | 0 | 2.0–3.0 |
| C | ≤0.08 | 0.04–0.10 | ≤0.08 | ≤0.08 |
| Fe | Balance | Balance | Balance | Balance |
Table 2 – Mechanical & Elevated-Temperature Properties
| Property | Room Temp. | 650 °C | 870 °C |
|---|---|---|---|
| Tensile Strength | ≥515 MPa | ≥320 MPa | ≥150 MPa |
| Yield Strength (0.2 %) | ≥205 MPa | ≥150 MPa | ≥85 MPa |
| Elongation in 2" | ≥40 % | ≥28 % | ≥30 % |
| Hardness HRB | ≤92 | — | — |
| Density | 8.0 g/cm³ (0.289 lb/in³) | — | — |
| Thermal Expansion | 17.2 µm/m·K (20–100 °C) | — | — |
Full Product Range Table
| Fitting Type | Size Range | Pressure Class | Standards | Finish |
|---|---|---|---|---|
| 321 stainless steel pipe fittings – butt-weld seamless | ½"–48" | Sch 5S/10S/40S/80S | ASTM A403 WP321/321H, ASME B16.9 | Pickled, 180G |
| 321 stainless steel pipe fitting – welded | 14"–48" | Sch 10S/20/40S | ASTM A403 WP321, ASME B16.9 | Pickled |
| Threaded NPT/BSPT | ⅛"–4" | 150 lb / 3000 lb | ASME B16.11, ISO 7-1 | Pickled |
| Socket-weld forged | ¼"–4" | 3000 lb / 6000 lb | ASME B16.11 | Pickled |
| Sanitary tri-clamp special | ½"–6" | 10 bar | Custom | Mirror Ra ≤0.4 µm |
| Special aviation elbows | ½"–8" | Custom | AMS 5645, ABS/DNV | Bright annealed |
Custom CNC-machined specials available on request.
Product Focus & Market Info
As one of the world’s largest specialized manufacturers of 321 stainless steel pipe fittings, we operate a 120 000 t/year automated forging and CNC finishing line dedicated to 321 stainless steel pipe fitting production. Our 150 000 m² facility keeps 25 000 t of ready stock, ensuring immediate availability for global EPC and aerospace contractors. Whether you need one pallet of 3" Sch 40S elbows or a full vessel of 20" × 12 m special-radius bends, our mill-direct pricing and ABS/DNV-approved quality give you the competitive edge. Contact our export team today for the most updated quotation and downloadable 3.1 MTC.
Specialty products include custom 321 stainless steel pipe fittings for aviation exhaust systems – tight-radius, thin-wall, and bright-annealed finishes.
Custom 321 Stainless Steel Pipe Fitting – From Standard Elbows to Aerospace-Grade Special Components
Main Applications
- Aircraft & piston-engine exhaust systems, turbo-charger ducts
- Furnace & boiler connections, radiant tubes, muffles, baskets
- Refinery cat-crackers, thermal oxidizers, flare stacks
- Superheater tubes, reheater supports, EGR piping
- Expansion joints, high-temperature chemical process lines
- Petrochemical crackers, muffle retorts, afterburners
Massive Stock of 321 Stainless Steel Pipe Fittings – Mill-Direct Prices, Full Traceability, Same-Day Shipping Worldwide
Why Choose Us – Aerospace-Approved Mill
- ASME, PED 2014/68/EU, EN 10204 3.1 & 3.2 MTC supplied
- ABS/DNV aviation approvals available – accepted by Boeing & Airbus Tier-1 suppliers
- 120 000 ton annual capacity – 5-day lead time for standard 321 stainless steel pipe fittings
- In-house CNC machining of special 321 stainless steel pipe fitting – tight-radius, thin-wall
- Same-day cutting, beveling, and PMI testing – lengths 3–12 m, tolerances ±0.2 mm
- Real-time stock portal – 24/7 visibility for any 321 stainless steel pipe fittings
Grade Comparison Table: 321 vs 304 vs 316 vs 310S vs 347 vs 321H Fittings
| Grade/Type | Ti % | Mo % | Max Temp (°C) | Weld Post-Treat | Pressure Rating | Relative Cost | Best Use |
|---|---|---|---|---|---|---|---|
| 321/321H | ≥5×C | 0 | 870 | Not needed | High | 1.1× | High-temp welded |
| 304 | 0 | 0 | 800 | Not needed | High | 1.0× | General service |
| 316 | 0 | 2–3 | 870 | Not needed | High | 1.35× | Marine chloride |
| 310S | 0 | 0 | 1150 | Not needed | High | 1.4× | Furnace radiant |
| 347 | Nb≥10×C | 0 | 870 | Not needed | High | 1.2× | Nuclear welded |
FAQ – 321 Stainless Steel Fittings
-
Why 321 instead of 304 after welding?
321 resists sensitisation and intergranular corrosion in the 425–850 °C range; 304 does not. -
What is the maximum service temperature?
870 °C continuous; intermittent to 900 °C with acceptable scaling rate. -
Price vs 304/316 fittings?
321 is ~10 % higher than 304, ~20 % lower than 316; longer life often offsets premium. -
Stock availability for special 321 stainless steel pipe fitting?
25 000 t ready stock; specials machined within 7 days. -
Lead time for large orders?
5 days for standard 321 stainless steel pipe fittings; 10 days for custom CNC specials. -
Which welding procedures are recommended?
TIG with ER321 filler; pre-heat not required; post-weld stabilising anneal optional. -
Do you supply ABS/DNV certificates?
Yes, included with each batch of 321 stainless steel pipe fittings for aerospace projects. -
Do you export worldwide?
Yes, to 70+ countries including USA, Germany, India, UAE, South Korea, and Brazil.
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Stop paying trader margins. Contact the world’s largest 321 stainless steel pipe fittings manufacturer today for the most competitive price, immediate access to massive stock, and same-day cutting of any 321 stainless steel pipe fitting.