Stainless steel welded U-tube

TOKO TECH offers Stainless steel welded U-tube as following:

Out diameter range: 6mm -600mm

Wall thickness range: 0.6-80mm

Grade: TP304L/H,TP316L/H/Ti, 321/H, 317L, 347H, 310S, N8904(904L), S31803,S32205,S32750,etc.

Standard: ASTM A312, ASTM A249, ASTM A269,ASTM A790, ASTM A789, GOST9941, EN10217-7,etc.

Surface finish: Annealed &Pickled; bright annealed &Polished

TOKO TECH Core Advantages

​Precision Forming: 3D laser alignment + servo-hydraulic bending. wall thinning ≤5%.

​Rigorous QC: Triple inspection (RT+UT+hydro test). ASME Section VIII Div.1 compliant.

​Flexible Production: Customizable OD 6-600mm, wall thickness 0.6-80mm. Non-standard U-bends delivered in 30 days

1.Material Options

​304/304L Austenitic Stainless Steel

​Properties: 18% Cr, 8% Ni. Resists weak acids/alkalis with excellent ductility. Post-weld heat treatment not required.

​Applications: Heat exchanger U-bends for food processing, HVAC piping. Minimum bend radius ≥3D (tube diameter).

​316/316L Molybdenum-Enhanced Stainless Steel

​Properties: 2-3% Mo. Chloride resistance (Cl⁻≤5000 ppm). Suitable for marine/chemical media.

​Applications: Seawater desalination U-bends, pharmaceutical condensers. Operating temperature: -50°C to 450°C.

​Duplex Steel 2205 (S31803)

​Properties: Austenitic-ferritic duplex structure. Yield strength ≥550 MPa, PREN ≥35. Resists stress corrosion (H₂S ≤1000 ppm).

​Applications: High-pressure oil/gas casing U-bends, acidic media heat exchangers.

​High-Temperature Alloy 310S (0Cr25Ni20)

​Properties: 25% Cr, 20% Ni. Oxidation resistance ≤1100°C with superior creep resistance.

​Applications: Boiler U-bend superheater tubes, pyrolysis furnace radiant coils.

​2. Compliance Standards & Certifications

​International Standards

​ASTM A312/A358: Covers TIG/Plasma welding with 100% X-ray (RT) weld inspection.

​EN 10217-7: EU pressure equipment standard limits wall thinning at bends to ≤8%.

​ASME BPE-2022: Medical-grade U-bends require Ra ≤0.4μm internal finish, SIP/CIP compatible.

​Key Certifications

​Process Certifications: ISO 3834 welding system, NACE MR0175 (sulfide corrosion resistance).

​Testing Reports: Hydrostatic test (2.5× working pressure), intergranular corrosion test (ASTM A262).

​3. Surface Treatments

​Weld Smoothing & Polishing

​Process: Internal argon shielding + external mechanical polishing. Ra ≤1.6μm eliminates fluid stagnation.

​Applications: Dairy-grade U-bends compliant with 3-A Sanitary Standards.

​Acid Pickling & Passivation (AP)

​Process: Full immersion pickling. Passivation layer ≥2.5nm. Salt spray resistance ≥720 hours (ASTM B117).

​Applications: Cost-effective chemical industry U-bends.

​Electropolishing (EP)

​Process: Electrochemical polishing to Ra ≤0.2μm. Reduces microbial adhesion by 95% (ASME BPE SF-2).

​Applications: Bioreactor U-bends, vaccine production equipment.

​Sandblasting + Coating

​Process: 80-grit alumina blasting (Ra 3.2-6.3μm) + PTFE coating. Temperature range: -196°C to 260°C.

​Applications: Aggressive media (e.g., concentrated H₂SO₄, HF) transfer tubes.

​4. Industry-Specific Solutions

​Oil & Gas Industry

• ​Configuration: Duplex 2205 + TIG welding + internal pickling.
• ​Performance: Pressure ≤25 MPa, H₂S corrosion rate ≤01 mm/year.
• ​Case: Middle East hydrocracker U-bends – zero leaks over 8 years.

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Food & Pharma Industry

• ​Configuration: 316L EP tubes + automated orbital welding.
• ​Performance: Internal Ra ≤0.2μm, dead volume <0.1%.
• ​Case: European lyophilizer U-bends – FDA 21 CFR Part 177 compliant.

​Power & Energy Industry

• ​Configuration: 310S alloy + internal shot peening.
• ​Performance: Operating temp. 800-1000°C, steam oxidation rate ≤0.05 mm/year.
• ​Case: China ultra-supercritical boiler U-bends – 100,000+ service hours.

​Marine Engineering

• ​Configuration: Super Duplex 2507 + external epoxy coating.
• ​Performance: Cl⁻corrosion resistance ≥30 years, cathodic protection (-800mV to -1100mV).
• ​Case: South China Sea cooling U-bends – 60% lower maintenance costs.

​Environmental Engineering

• ​Configuration: 6Mo alloy + PTFE lining.
• ​Performance: Resists 98% H₂SO₄, 40% HF (≤150°C).
• ​Case: Hazardous waste acid gas lines – 50% cost savings vs. Hastelloy.