Stainless steel seamless U-tube

TOKO TECH offers Size range: O.D.:6.35-50.8mm, W.T.: 0.7-4.0mm

TOKO TECH offers Length: according to client’s requirement

TOKO TECH offers Standard: ASTM A213, ASME SA213, ASTM A269

TOKO TECH offers Grade: TP304 Seamless U tube, TP304L Seamless U tube, TP316L seamless U tube, TP316 Seamless U tube, TP321 seamless U tube

TOKO TECH offers Finished: Heat treatment and pickled

Material Options

TOKO TECH offers a full range of stainless steel U-bend tubes for extreme operational demands:

304/304L Austenitic Stainless Steel

• ​Properties: 18% Cr, 8% Ni. Balances corrosion resistance and formability. Ideal for food, pharmaceutical, and mildly corrosive environments.
• ​Applications: U-bend heat exchanger tubes, low-temperature condensers. Minimum bend radius ≥3× tube diameter (DN), crack-free bending.

316/316L Molybdenum-Enhanced Stainless Steel

• ​Properties: 2-3% Mo improves chloride resistance by 50%. Suitable for marine and chemical environments.
• ​Applications: Seawater desalination evaporator tubes, acid transfer lines. Tolerates Cl⁻≤5000 ppm.

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Duplex Steel 2205 (S31803)

• ​Properties: Austenitic-ferritic structure. Yield strength ≥450 MPa, excellent stress corrosion cracking (SCC) resistance.
• ​Applications: Oil/gas well casings, high-pressure heat exchangers. Resists H₂S/CO₂in sour environments.

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High-Temperature Alloy 310S (0Cr25Ni20)

• ​Properties: 25% Cr, 20% Ni. Oxidation resistance up to 1100°C, anti-carburization.
• ​Applications: Boiler U-bend superheater tubes, pyrolysis furnace tubes. Long-term service ≤1000°C.

​2. Compliance Standards

​International Standards

• ​ASTM A312/A789: Covers dimensional tolerances and mechanical properties for seamless/welded austenitic tubes.
• ​ASTM A213: Mandates grain size and hardness control for boiler/exchanger tubes.
• ​EN 10216-5: EU standard for pressure equipment, including U-bend forming and NDT requirements.
• ​ASME BPE: Specifies surface finish and cleanliness for biopharmaceutical-grade tubes.

​Certifications

• PED 2014/68/EU, NACE MR0175 (sulfide corrosion resistance)

​3. Surface Treatments

​Acid Pickling & Passivation (AP)

• ​Process: Nitric-hydrofluoric acid mix removes scale, forming Cr₂O₃passive layer (Ra ≤6μm).
• ​Applications: General-purpose U-bends for chemical/energy industries. Cost-effective corrosion protection.

​Electropolishing (EP)

• ​Process: Electrochemical smoothing achieves Ra ≤0.2μm, reducing microbial adhesion by 90%.
• ​Applications: Pharma/dairy U-bends. Complies with ASME BPE SF-4 standards.

​Sandblasting

• ​Process: 120-180 grit abrasives create Ra 3.2-6.3μm for enhanced coating adhesion.
• ​Applications: U-bends with PTFE/ceramic coatings for aggressive environments.

​Bright Annealing (BA)

• ​Process: Argon-protected annealing yields oxide-free surface (Ra ≤0.8μm).
• ​Applications: Semiconductor vacuum lines, high-purity fluid transfer tubes.

​4. Selection Guidelines

​Industry-Specific Solutions

• ​Petrochemical Industry:
  • ​Material: Duplex 2205 (sour service), 316L (chlor-alkali media).
  • ​Process: AP + 100% PT inspection. Bend radius ≥5D (D = tube diameter).
• ​Power & Energy:
  • ​Material: 310S (boiler tubes), TP347H (ultra-supercritical units).
  • ​Process: Internal shot peening to enhance steam oxidation resistance.
• ​Food & Pharma:
  • ​Material: 316L electropolished tubes.
  • ​Process: 3-A compliant, Ra ≤0.4μm, supports CIP/SIP cleaning.
• ​Marine Engineering:
  • ​Material: Super Duplex 2507 (seawater corrosion resistance).
  • ​Process: External sandblasting + epoxy coating; internal EP.

​Operational Parameter-Based Selection

• ​Pressure Rating:
  • Low pressure (≤5MPa): Thin-wall (δ=1-3mm), 304 material.
  • High pressure (≥10MPa): Thick-wall (δ≥5mm), 316L/Duplex. Mandatory 100% UT inspection.
• ​Temperature Range:
  • Cryogenic (-196°C to 200°C): 304/304L (avoids low-temperature embrittlement).
  • High temp (500-1000°C): 310S/Alloy 800H (controls grain growth).
• ​Media Corrosivity:
  • Weak acids (pH≥4): 304 AP tubes.
  • Strong acids (H₂SO₄, HCl): Hastelloy C-276 or lined U-bends.

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Design-Driven Selection

• ​Bend Radius:
  • Compact: R=1.5D (requires specialized bending; material elongation ≥35%).
  • Standard: R=3D (covers 90% of applications).
• ​End Preparation:
  • Plain ends: For flange connections.
  • Bevelled ends: TIG welding with internal argon shielding to prevent oxidation.

​5. Why Choose TOKO TECH?

Smart Manufacturing Strength: TOKO TECH’s fully automated bending lines support OD 6-630mm and R1.5D-10D bend radii.

Rapid Response: 72-hour technical proposal + 15-day delivery. Free prototyping for non-standard designs.

Rigorous Testing: Eddy current testing (ET) + hydrostatic test (1.5× working pressure).