Seamless Low-carbon Steel Tubes For Efficient Heat Transfer
Astm a179 u-bend tubes are seamless low-carbon steel tubes designed for heat exchangers and condensers.
Seamless Low-carbon Steel Tubes For Efficient Heat Transfer
Astm a179 u-bend tubes are seamless low-carbon steel tubes designed for heat exchangers and condensers.
ASTM A179 U-Bend Tubes are seamless, cold-drawn low-carbon steel tubes designed for heat exchanger tubes and condensers, offering superior corrosion resistance and thermal conductivity. Conforming to ASTM A179/ASME SA179 specifications, these U-shaped tubing solutions are widely used in industries such as petrochemical, power generation, chemical processing, and food and beverage, where pipeline durability and efficient heat transfer are essential. The U-bend design acts as a thermal expansion absorber, reducing stress in compact heat exchanger systems.
Manufactured through a cold-drawing process, ASTM A179 U-Bend Tubes are produced with outer diameters ranging from 12.7mm to 38.1mm, wall thicknesses from 1.65mm to 2.77mm, and bend radii from 1.5 times the outer diameter to 1250mm. Leg lengths can be customized up to 26 meters, meeting diverse project requirements. Post-bending heat treatment at 1200°F (650°C) or higher ensures stress relief and optimal mechanical properties, while surface treatments like varnishing, pickling, or galvanization enhance corrosion resistance. The tubes are packed in wooden boxes or bundles with plastic caps to prevent contamination during transport.
These boiler tubes undergo rigorous testing, including hydrostatic, flaring, flattening, and hardness tests, to comply with ASTM A450/A450M standards. With a minimum tensile strength of 325 MPa, yield strength of 180 MPa, and elongation of 35%, they are designed for efficient heat transfer in low-to-medium temperature applications (up to 450°C). The low-carbon steel composition (0.06-0.18% carbon, 0.27-0.63% manganese) ensures excellent weldability and formability, making them suitable for bending and flanging without cracking.
Compared to ASTM A192 tubes, ASTM A179 U-Bend Tubes are optimized for lower-pressure, lower-temperature applications, making them ideal for tubular heat exchangers and condensers. Their seamless construction minimizes the risk of leaks, ensuring reliable performance in corrosive environments, such as those involving water or chemical fluids. The U-bend design eliminates the need for additional fittings or expansion joints, reducing installation costs and space requirements in heat exchanger systems.
The ASTM A179 U-Bend Tubes address critical challenges like pipeline wear, corrosion, and thermal stress in industrial systems. Their high thermal conductivity, durability, and ease of maintenance make them a preferred choice for engineers seeking reliable heat exchanger tubes for applications requiring consistent performance and longevity in demanding environments.
Precision tube bending ensures ASTM A179 tubes maintain their structural integrity and performance in heat exchanger and boiler applications.
Proper bending techniques and quality inspections ensure ASTM A179 tubes deliver consistent performance in high-pressure and high-temperature environments.
Engineered to meet diverse industrial needs with robust materials and versatile designs.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.06-0.18 |
| Manganese (Mn) | 0.27-0.63 |
| Phosphorus (P) | ≤0.035 |
| Sulfur (S) | ≤0.035 |
| Property | Value |
|---|---|
| Tensile Strength, min (MPa) | 325 |
| Yield Strength, min (MPa) | 180 |
| Elongation, min (%) | 35 |
| Hardness, max (HRB) | 72 |
ASTM A450 covers carbon and low alloy steel tube. Steel samples shall be melt processed and shall either be ingot cast or strand cast. Heat and product analyses shall be performed on the steel materials. Steel specimens shall also undergo tensile tests and shall conform to required values of yield strength and elongation. Flattening test, reverse flattening test, flaring test, flange test, hardness test, hydrostatic test, air underwater pressure test, and nondestructive tests shall be performed on the steel materials.
| OD (in / mm) | ≤0.095 in (2.4 mm) | 0.095–0.150 in (2.4–3.8 mm) | 0.150–0.180 in (3.8–4.6 mm) | >0.180 in (>4.6 mm) | ||||
|---|---|---|---|---|---|---|---|---|
| Seamless ± | Welded ± | Seamless ± | Welded ± | Seamless ± | Welded ± | Seamless ± | Welded ± | |
| ≤4 in (≤101.6 mm) | 40 / 0% | 18 / 0% | 35 / 0% | 18 / 0% | 33 / 0% | 18 / 0% | 28 / 0% | 18 / 0% |
| >4 in (>101.6 mm) | – | – | 35 / 0% | 18 / 0% | 33 / 0% | 18 / 0% | 28 / 0% | 18 / 0% |
| Tube Type | OD Range | + (in / mm) | – (in / mm) |
|---|---|---|---|
| Hot‑Finished Seamless | ≤4 in (≤101.6 mm) | +1⁄64″ (0.4 mm) | –1⁄32″ (0.8 mm) |
| >4–7½ in (101.6–190.5 mm) | +1⁄64″ (0.4 mm) | –3⁄64″ (1.2 mm) | |
| Welded & Cold‑Finished Seamless | ≤1 in (≤25.4 mm) | +0.004″ (0.1 mm) | –0.004″ (0.1 mm) |
| 1 – 1½ in (25.4–38.1 mm) | +0.006″ (0.15 mm) | –0.006″ (0.15 mm) | |
| 1½ – 2 in (38.1–50.8 mm) | +0.008″ (0.2 mm) | –0.008″ (0.2 mm) | |
| 2 – 2½ in (50.8–63.5 mm) | +0.010″ (0.25 mm) | –0.010″ (0.25 mm) | |
| 2½ – 3 in (63.5–76.2 mm) | +0.012″ (0.30 mm) | –0.012″ (0.30 mm) | |
| 3 – 4 in (76.2–101.6 mm) | +0.015″ (0.38 mm) | –0.015″ (0.38 mm) | |
| 4 – 7½ in (101.6–190.5 mm) | +0.015″ (0.38 mm) | –0.025″ (0.64 mm) | |
| 7½ – 9 in (190.5–228.6 mm) | +0.015″ (0.38 mm) | –0.045″ (1.14 mm) | |
ASTM A179 (ASME SA179) specifies seamless, cold-drawn low-carbon steel tubes for heat exchangers, condensers, boilers, and similar heat-transfer equipment, with outside diameters from 1/8″ to 3″ (3.2 – 76.2 mm).
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.
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
| 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) |
| 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) |
| 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) |
| >5m | +3/16"(5mm) | |
| Total tube length including radius | ≤6m | +3/16"(5mm) |
| >6m | +5/16"(8mm) |
U-Tube heat exchangers are known for their distinctive U-shaped tubes that offer several advantages and also come with certain limitations.
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.
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.
U-bend tubes are used to transfer heat between fluids.
Transfers heat between fluids, allowing return flow at 180° in a compact space.
Used in heat exchangers, chemical & petrochemical, food processing, and refrigeration industries.
Applied in heat exchangers at Oil & Gas, petrochemical plants, refineries, and power plants.
Handles aggressive fluids like sodium hydroxide + sodium hypochlorite safely.
Allows pipeline expansion without buckling; flexible or sliding options available.
Enhances heat transfer when the outside coefficient is lower than the inside, improving efficiency.
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