ASTM A213 TP347H Stainless Steel U Bend Tube
Standard：ASTM A213 / ASME SA213
Material Grade：TP347H, UNS S34709, 1.4961
Manufacturing Process：Seamless, Cold Drawn
Tube Type：U Bend Heat Exchanger Tube
Outside Diameter (OD)：6.35 mm – 76.2 mm (1/4" – 3")
Wall Thickness (WT)：0.7 mm – 8.0 mm
Straight Length Before Bending:Up to 25 m
Finished U Tube Length:Up to 30 m (Custom Available)
Bending Radius:≥1.5 × OD or as per customer drawing
Leg Length Tolerance:±3 mm
Overall Length Tolerance:±5 mm
Ovality After Bending:≤10% of OD
Wall Thinning at Bend:≤12% or according to project specification
Heat Treatment:Solution Annealed & Pickled
Surface Finish:Annealed & Pickled (AP), Bright Annealed (BA)
Tube Ends:Plain End (PE), Deburred, Square Cut
ASTM A213 TP347H U Bend Tube Manufacturer
GNEE Stainless Steel is a leading manufacturer and supplier of straight tubes, seamless U-bend tubes, seamless coils, long-length coils, straight heat exchanger tubes, boiler tubes, superheater tubes, reheater tubes, and custom-fabricated tubing.
Our ASTM A213 TP347H U-bend tubes are fabricated from premium-grade seamless tubes. Throughout the manufacturing process, the bending radius, wall thinning rate, and ovality are strictly controlled to guarantee uniform heat transfer performance and an extended service life.
To achieve 100% relief of residual stress, localized electrical resistance solution annealing is performed on the bend radius (R-portion) and extended 300 mm into the straight legs. We guarantee a maximum hardness not exceeding 190 HV, effectively eliminating the risk of stress corrosion cracking (SCC) during high-pressure superheater operations. Furthermore, the grain size across the entire tube-including the bend heat-affected zone (HAZ)-is strictly maintained at ASTM 7 or coarser. This ensures the exceptional creep-rupture strength required for environments ranging from 540°C to 815°C, extending equipment life by more than 20% compared to non-standard heat-treated products.
Production process of TP347H U-bend tubes
In addition, our SS 347H U-tubes undergo a 100% drift test (using a ball diameter equal to 80% of the tube ID) to guarantee a completely blockage-free inner surface, while keeping ovality strictly within 5%. Post-heat treatment, all tubes undergo internal descaling and nitrogen purging to ensure heat exchange efficiency remains unimpeded by contaminants.
The leg length tolerance of our ASTM A213 TP347H U-tubes is held within ±1.5 mm, and the center-to-center distance tolerance is controlled within ±0.5 mm. This high-precision alignment ensures 100% first-time successful fit-up through the tube sheet, significantly reducing your on-site assembly labor and welding preparation time.
Specification
| Specification | Details |
|---|---|
| Material Grade | TP347H, UNS S34709, 1.4961 |
| Manufacturing Process | Seamless, Cold Drawn |
| Tube Type | U Bend Heat Exchanger Tube |
| Outside Diameter (OD) | 6.35 mm – 76.2 mm (1/4" – 3") |
| Wall Thickness (WT) | 0.7 mm – 8.0 mm |
| Straight Length Before Bending | Up to 25 m |
| Finished U Tube Length | Up to 30 m (Custom Available) |
| Bending Radius | ≥1.5 × OD or as per customer drawing |
| Leg Length Tolerance | ±3 mm |
| Overall Length Tolerance | ±5 mm |
| Ovality After Bending | ≤10% of OD |
| Wall Thinning at Bend | ≤12% or according to project specification |
| Heat Treatment | Solution Annealed & Pickled |
| Surface Finish | Annealed & Pickled (AP), Bright Annealed (BA), Polished |
| Tube Ends | Plain End (PE), Deburred, Square Cut |
| Inspection Certificate | EN 10204 3.1 / 3.2 |
| Third-Party Inspection | SGS, BV, TUV, Lloyd's Register, DNV |
| Packing | Wooden Cases, Plywood Boxes, Plastic Caps, Individual Protection for U Bend Legs |
| Applications | Heat Exchangers, Condensers, Boilers, Superheaters, Reheaters, Petrochemical Plants, Power Plants, Refineries |
Wall thickness in U bent portion
The wall thickness of the tube in the U-bent section shall not be less than value determined by the equation:
Where:
tf is wall thickness after bending in. [mm]
T is specified minimum tube wall thickness in. [mm]
R is centerline bend radius in[mm]
D is nominal outside tube diameter in[mm].
Why use U Bend tubes in heat exchangers?
U-bend tubes are used in shell-and-tube heat exchangers because they allow the tube bundle to expand and contract freely, eliminating the risk of thermal stress damage. This configuration cuts manufacturing costs by requiring only a single tubesheet and eliminates the need for an expansion joint.
What is the maximum operating temperature of TP347H?
The maximum continuous operating temperature for TP347H stainless steel is typically 870°C to 899°C (1600°F to 1650°F). For intermittent service, it can withstand temperatures up to 925°C (1700°F). When used for structural pressure parts, allowable stress ratings are typically optimized for use up to 650°C (1200°F).
What bend radius is available for TP347H U tubes?
For TP347H (ASME SA213/A213) seamless U tubes, the available centerline bend radius typically ranges from a minimum of 1.5 × OD (Outside Diameter) up to 1,250 mm or more, depending on the exact manufacturing capabilities and standards.
Applications of ASME SA213 TP347H Seamless Tubes
Power Generation: Superheater and reheater coils.
Oil & Gas / Refining: Heat exchanger and condenser tubes in fluid catalytic cracking (FCC) units and hydroprocessing facilities.
Chemical Processing: High-temperature process lines and heat recovery steam generators (HRSGs).
Power Generation
Oil & Gas / Refining
Chemical Processing
Stainless Steel U bend Tube Export Record
Export ASME SA213 TP316L Stainless Steel U bend Tubes, OD 25.4mm, WT 2.11mm Total in 9800KGS.
Export ASME SA213 TP304L U bend Stainless Steel Tubes, OD 25.4mm, WT 2.11mm Total in 5900KGS.
Export ASME SA213 TP321 U bend Tubes, OD 25.4mm, WT 2.11mm Total in 25000KGS.
Export ASME SA213 TP310S U bend Tubes, OD 25.4mm, WT 2.1mm, ST Length 3615mm, Total 710Pcs
Could you please provide the project requirements so that I can better assist you? I can help by estimating pipe wall thickness and bending radii based on your pressure and temperature parameters, supplying custom U-bends, and sourcing the matching filler metal (such as ER347) for installation.
Quality Control
| Test Category | Description |
| Non-Destructive Test | 100% Eddy Current (ECT) and 100% Ultrasonic Testing (UT) |
| Hydrostatic Test | Performed after bending; 1.5×design pressure (Max 20 MPa) |
| Ball Pass Test | 100% verification with precision SS ball (80% of Tube ID) |
| Surface Inspection | 100% Dye Penetrant Test (PT) on the bend radius area |
| Corrosion Test | ASTM A262 Practice E (Intergranular Corrosion Test) |
| Hardness Check | Verification of max 190 HV in the heat-treated bend zone |
High-quality sea freight packaging
Traceability: Each tube is stenciled with Heat No., Lot No., Standard, Grade, and Size.
Protection: Ends are deburred and fitted with high-density plastic caps.
Crating: Tubes are packed in sea-worthy steel-framed wooden cases with individual spacers to prevent tube-to-tube contact and bending of the U-structure.
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