Titanium Alloy U-Bent Tube : Lightweight, Corrosion-resistant Tubes For Extreme Environments

Titanium Alloy U-Bent Tubes are seamless or welded tubes made from titanium alloys (e.g., Grades 2, 5, 9) bent into a U-shape for use in heat exchanger tubes and boiler tubes. Conforming to standards like ASTM B338 and ASME SB338, these tubes are designed for high-temperature, high-pressure, and corrosive environments in industries such as aerospace, marine, chemical processing, and power generation. Their exceptional corrosion resistance, lightweight tubing properties, and ability to act as a thermal expansion absorber ensure pipeline durability in demanding applications.

Manufactured via cold-working methods, Titanium Alloy U-Bent Tubes feature outer diameters from 9.53mm to 38.1mm, wall thicknesses from 0.7mm to 5mm, and bend radii from 1.5D to 1500mm, customizable per client specifications. Post-bending heat treatments, such as stress relief annealing at 540-650°C, optimize mechanical properties and prevent cracking. Surface treatments like pickling or polishing enhance corrosion resistance, and plastic caps protect tube ends during transport. The alloy’s low density (4.51 g/cm³) and high strength make it ideal for weight-sensitive applications.

These tubes undergo rigorous testing, including hydrostatic, eddy current, flaring, flattening, and ultrasonic tests, to comply with ASTM B338 and TEMA standards. With tensile strengths ranging from 345 MPa (Grade 2) to 860 MPa (Grade 5) and yield strengths from 275 MPa to 550 MPa, they are engineered for temperatures up to 600°C and pressures up to 10 MPa. The U-bend design minimizes thermal stress, eliminates expansion joints, and reduces installation costs, making them ideal for compact heat exchanger systems in corrosive environments like seawater or chemical fluids.

Titanium alloys, such as Grade 2 (commercially pure) and Grade 5 (Ti-6Al-4V), offer a high strength-to-weight ratio and excellent resistance to seawater, acids, and chloride-induced stress corrosion cracking. Compared to stainless steel, titanium alloys provide superior corrosion resistance in marine and chemical applications, while their biocompatibility makes them suitable for medical and food processing equipment. These tubes are ideal for heat exchangers, condensers, evaporators, and intercoolers in industries requiring lightweight tubing with robust performance.

Addressing challenges like pipeline wear, corrosion, and thermal stress, Titanium Alloy U-Bent Tubes provide a reliable solution for engineers seeking durable heat exchanger tubes. Their high strength, low thermal expansion, and long-term durability make them a preferred choice for critical applications in extreme environments, ensuring efficiency and minimal maintenance

Advantages of Titanium Alloy U Bent Tubes

Titanium U-bend tubes are widely used in boilers, condensers, heat exchangers, coolers, and critical process equipment across industries including oil & gas, chemical, power, steel, sugar, and renewable energy plants.

Corrosion Resistance

Outstanding resistance to seawater and chemical corrosion, ensuring long-term durability in harsh environments.

High Strength-to-Weight Ratio

Titanium alloys deliver excellent mechanical strength while remaining significantly lighter than steel.

Lightweight

Reduces overall equipment weight, improving handling and efficiency in transport and installation.

Heat Transfer Efficiency

U-bend design increases surface area, enhancing heat transfer performance for critical applications in power and process industries.

Longevity

Exceptional fatigue and wear resistance ensures extended service life and reduced maintenance downtime.

Chemical Composition of Titanium Alloy U-Bent Tubes (ASTM B338 Grade 2)
Element	Composition (%)
Titanium (Ti)	Balance
Iron (Fe)	≤0.30
Oxygen (O)	≤0.25
Carbon (C)	≤0.08
Nitrogen (N)	≤0.03
Hydrogen (H)	≤0.015

Mechanical Properties of Titanium Alloy U-Bent Tubes (ASTM B338 Grade 2)
Property	Value
Tensile Strength, min (MPa)	345
Yield Strength, min (MPa)	275
Elongation, min (%)	20
Hardness, max (HBW)	160

Chemical Composition of Titanium Alloy U-Bent Tubes (ASTM B338 Grade 5)
Element	Composition (%)
Titanium (Ti)	Balance
Aluminum (Al)	5.5-6.75
Vanadium (V)	3.5-4.5
Iron (Fe)	≤0.40
Oxygen (O)	≤0.20
Carbon (C)	≤0.08
Nitrogen (N)	≤0.05
Hydrogen (H)	≤0.015

Mechanical Properties of Titanium Alloy U-Bent Tubes (ASTM B338 Grade 5)
Property	Value
Tensile Strength, min (MPa)	860
Yield Strength, min (MPa)	550
Elongation, min (%)	10
Hardness, max (HBW)	334

FAQs

Engineered to meet diverse industrial needs with robust materials and versatile designs.

Titanium Alloy U-Bent Tubes are seamless or welded tubes made from titanium alloys (e.g., Grades 2, 5) bent into a U-shape for heat exchangers and boilers, offering superior corrosion resistance and lightweight properties.

Used in heat exchangers, condensers, evaporators, and intercoolers in aerospace, marine, chemical processing, and power generation industries.

Titanium alloys offer excellent corrosion resistance to seawater, acids, and chlorides, high strength-to-weight ratio, and biocompatibility, ideal for marine, chemical, and medical applications.

For Grade 2:
- Titanium (Ti): Balance
- Iron (Fe): ≤0.30%
- Oxygen (O): ≤0.25%
- Carbon (C): ≤0.08%
- Nitrogen (N): ≤0.03%
- Hydrogen (H): ≤0.015%

For Grade 5:
- Titanium (Ti): Balance
- Aluminum (Al): 5.5-6.75%
- Vanadium (V): 3.5-4.5%
- Iron (Fe): ≤0.40%
- Oxygen (O): ≤0.20%
- Carbon (C): ≤0.08%
- Nitrogen (N): ≤0.05%
- Hydrogen (H): ≤0.015%

For Grade 2:
- Tensile Strength: ≥345 MPa
- Yield Strength: ≥275 MPa
- Elongation: ≥20%
- Hardness: ≤160 HBW

For Grade 5:
- Tensile Strength: ≥860 MPa
- Yield Strength: ≥550 MPa
- Elongation: ≥10%
- Hardness: ≤334 HBW

Outer diameters range from 9.53mm to 38.1mm, wall thicknesses from 0.7mm to 5mm, with bend radii of 1.5D to 1500mm. Tolerances comply with ASTM B338 and TEMA standards.

Produced via cold-working, followed by mandrel bending and stress relief annealing at 540-650°C to enhance properties and prevent cracking.

Tests include hydrostatic, eddy current, flaring, flattening, and ultrasonic tests to ensure compliance with ASTM B338 and TEMA standards.

Installed in heat exchanger or boiler tube sheets with welded or expanded ends, using gas tungsten arc welding (GTAW) with inert gas shielding to prevent oxidation.

Titanium alloy U-bent tubes offer superior corrosion resistance in seawater and chemical environments, and a higher strength-to-weight ratio, but are more expensive than stainless steel.

U-Bend Fabrication Tolerances

U-bend tubes are widely used in heat-exchanger systems. Heat-exchanger equipment on the basis of seamless stainless U-tubes is essential in strategically important and critical fields — nuclear and petrochemical machine building.

U-tube explanation

a...................The difference in length between two straight pipe sections
c..............The tangent spacing of the outer wall of the elbow
Da............nominal steel pipe outer diameter
E..............The distance between the outer diameters of the two straight ends
f...............the distance between the ends of the two straight ends
l............... straight tube length
Lg............. straight pipe section plus total length of pipe
Rm...........nominal bending radius
S.............nominal wall thickness
Smin.......The minimum wall thickness at the back of the elbow
t...............the bend deviates from the horizontal distance
So...........Standard minimum wall thickness

Tube Bending Tolerance Specifications
Item	Condition (when)	Tolerance
Ovality	Nominal bend radius ≤ 2 x nominal OD	less than or equal to 12%
	2 x nominal OD < Nominal bend radius ≤ 4 x nominal OD	less than or equal to 10%
	Nominal bend radius > 4 x nominal OD	less than or equal to 5%
	Nominal bend radius ≤ 2 x nominal OD	0.75 x nominal wall
Minimum wall thickness	2 x nominal OD < Nominal bend radius ≤ 4 x nominal OD	0.8 x nominal wall
	Nominal bend radius > 4 x nominal OD	0.9 x nominal wall
	Nominal bend radius ≤ 8" (200mm)	+/-3/64"(1mm)
Bending Radius	8" (200mm) < Nominal bend radius ≤ 16" (400mm)	+/-1/16"(1mm)
Bending Radius	Nominal bend radius >16" (400mm)	+/-5/64"(1mm)
Distance between legs	-	Max 1/16"(1.5mm)
Wall thinning of bending area	-	Max 17%
Difference between leg lengths at the ends	Leg length ≤ 16' (4.88m)	+1/8"(3mm)
Difference between leg lengths at the ends	Leg length > 16' (4.88m)	+3/16"(5mm)
Deviation from plane of bend	-	≤ 3/16"(1.5mm)
Flattening on bend	-	≤ 10% nominal diameter
Straight leg length	≤5m	+1/8"(3mm)
Straight leg length	>5m	+3/16"(5mm)
Total tube length including radius	≤6m	+3/16"(5mm)
Total tube length including radius	>6m	+5/16"(8mm)

U-Tube heat exchanger Pros and Cons

U-Tube heat exchangers are known for their distinctive U-shaped tubes that offer several advantages and also come with certain limitations.

Pros:

The U-tube heat exchanger features a single tubesheet with both ends of the tubes secured to it. This design allows the tubes to expand and contract freely, avoiding thermal stress and offering excellent thermal compensation. A double tube pass is utilized, providing a lengthy process path, high flow rates, and superior heat transfer performance with robust pressure resistance. The tube bundle is removable from the shell for convenient maintenance and cleaning, presenting a simple structure and low cost.

Cons:

Limitations imposed by the elbow's curvature radius restrict the arrangement of heat exchange tubes. This results in a larger inner tube spacing within the tube bundle and a lower utilization rate of the tube sheet. The shell-side fluid is prone to short-circuiting, which can impede heat transfer. When a tube leaks or sustains damage, only the U-shaped tubes on the outer part of the bundle can be readily replaced. Damage to the inner heat exchange tubes is not as easily repairable and may require blocking off. Furthermore, the damage to a single U-shaped tube equates to the loss of two tubes, leading to a higher scrap rate.

Titanium Alloy U-Bent Tube

Titanium Alloy U-Bent Tube