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| Nome da marca: | YUHONG |
| Número do modelo: | Tubo trocador de calor com curvatura em aço carbono ASME SA179 |
| MOQ: | 1000kg |
| Condições de pagamento: | L/C,T/T |
ASTM A179 / ASME SA179 Carbon Steel Heat Exchanger Tube Seamless Steel U Bend Tube
The ASTM A179 / ASME SA179 specification is unique because it requires the steel to be "Killed."
During the steelmaking process, oxygen is removed (deoxidized) using elements like silicon or aluminum. This produces a more homogenous, sound steel with no gas porosity. Many people assume all steel is killed. It's not. The fact that SA179 requires it makes it superior for bending. Non-killed (rimmed) steel has variable grain size and inclusions. When you U-bend non-killed steel, the inclusions elongate and can create "stringers" that act as starting points for cracks along the extrados (outer curve) of the bend. If a supplier tries to substitute a cheaper, non-killed steel, the U-bend will have a high reject rate during dye penetrant inspection.
Why SA179 here?
Cost vs. Copper: While copper tubes offer better heat transfer, they are expensive and susceptible to erosion from high-velocity water. SA179 steel tubes are thicker and more durable against water treatment chemicals, though they are heavier.
The "Cleanliness" Factor: In closed-loop HVAC systems (where the water is treated and recirculates), SA179 provides a long, corrosion-free life if the water chemistry is maintained.
ASTM A179 / ASME SA 179 Carbon Steel Seamless Tube Chemical Composition
| Element | Carbon | Manganese | Phosphorus | Sulfur |
| Grade | 0.06-0.18 | 0.27-0.63 | 0.035 | 0.04 |
ASTM A179 / ASME SA 179 Carbon Steel Seamless Tube Material Mechanical Properties
| Yield Strength(MPa) | Tensil Strength(MPa) | Elogation(%) |
| ≥180 | ≥325 | ≥35 |
Comparison with Similar Grades
| Grade | Standard | Key Difference |
|---|---|---|
| SA179 | ASME | Cold-drawn, mandatory heat treatment, fine grain, higher ductility. |
| SA192 | ASME | Higher carbon (0.06–0.18% C), higher tensile (≥55 ksi), for boilers. |
| SA210 A1 | ASME | Medium-carbon steel (C ≤0.27%), higher strength, for boiler tubes. |
| EN 10216-2 P195 | EN | Similar low-carbon seamless, slightly different mechanicals. |
| JIS G3461 STB340 | JIS | Japanese equivalent; comparable properties. |
Galvanic Corrosion at the Bend (The Tube Sheet Connection)
Dissimilar Metals: The U-bend tube (carbon steel) is usually rolled or welded into a tubesheet. That tubesheet might be carbon steel (safe), but often it is clad with stainless steel or even made of a different alloy for corrosion resistance.
The Crevice: At the point where the tube enters the tubesheet, there is a tiny crevice. If water gets in there and the tubesheet is stainless steel while the tube is carbon steel (SA179), the carbon steel becomes the anode and will corrode rapidly (galvanic corrosion).
The "Bend" Connection: This corrosion usually happens at the straight leg. But if the corrosion is severe, it weakens the leg, and the vibration from the process causes the bend to whip around and hit adjacent tubes (tube fretting). The failure shows up at the bend, but the cause is at the joint.
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