What Is ASTM A179 Low Carbon Pressure Pipe
ASTM A179 covers seamless cold-drawn low-carbon steel tubes for tubular heat exchangers, condensers and similar heat-transfer equipment, and ASME SA179 adopts the same requirements for code applications. The grade exists because a heat exchanger tube has to conduct heat efficiently while containing pressure, so the specification controls carbon content, grain structure, bore finish and dimensional accuracy together.
Tubes are produced by cold drawing a pierced billet or mother tube to the finished size, followed by annealing, straightening, pickling and testing. Cold drawing delivers the tight wall tolerance and smooth bore needed for rolling into a tube sheet, and the annealed condition keeps the metal ductile enough for expansion without cracking.
Purchase orders normally complete the specification with the general requirements of ASTM A450 / ASME SA450, which covers delivery condition, tolerances, testing and marking.
Chemical Composition of ASTM A179 Tubes
The heat analysis limits are low-carbon and narrow, which protects ductility and thermal conductivity.
| Element | Requirement, % |
|---|---|
| Carbon | 0.06-0.18 |
| Manganese | 0.27-0.63 |
| Phosphorus | 0.035 max |
| Sulfur | 0.035 max |
| Silicon | 0.25 max |
Mechanical Properties
| Property | Requirement |
|---|---|
| Yield strength, 0.2% offset | 180 MPa minimum |
| Tensile strength | 325 MPa minimum |
| Elongation in 50 mm | 35% minimum |
Tubes are supplied in the cold-drawn and annealed condition, and the specification also applies a hardness limit that keeps the material suitable for tube-sheet expansion.
Sizes, Tolerances and Testing
Heat-transfer tubes in this grade are commonly supplied from 6.0 mm to 114.0 mm outside diameter, with wall thickness from 1 mm to 15 mm and lengths up to 12,000 mm. Because the tubes pass through baffle plates and are rolled into tube sheets, diameter, wall and straightness tolerances are tighter than for general-purpose pipe, and the bore must be free from scale, seams and deep pits.
Each lot is normally verified by tensile testing together with a flattening or bend test and a non-destructive examination. Eddy-current testing, hydrostatic testing or the air-under-water test can be specified, and the mill issues a report that links the tubes to the heat number.
Applications and Service Conditions
Typical uses are shell-and-tube heat exchangers, surface condensers, feedwater heaters and turbine condensers in chemical plants, refineries and power stations. The grade is chosen for thermal duty and pressure containment rather than for creep strength, so it is not a substitute for alloy grades where metal temperatures are higher. Media must also be compatible with ferritic carbon steel, so tube material, water chemistry and cleaning practice are selected together to keep wall loss inside the corrosion allowance.
Handling and Installation Notes
Compare grade, size and wall tolerance with the tube-sheet drawing before cutting.
Keep the bore clean in storage, because shop soil is a common cause of early fouling.
Expand to the roll torque recommended for the tube-sheet material and re-test the joints.
Support the tubes on timber so that mill straightness is preserved.
FAQ
Q: Is ASTM A179 the same as ASME SA179?
Yes, the two designations describe one product and the chemistry and mechanical requirements are identical.
Q: What is the maximum service temperature?
The grade is intended for moderate-temperature heat-transfer duty, so the design temperature comes from the exchanger calculation rather than from a fixed grade limit.
Q: Which sizes are available?
Outside diameters from about 6.0 mm to 114.0 mm with wall thickness from 1 mm to 15 mm are typical.
Q: Is the tube welded or seamless?
ASTM A179 is a seamless, cold-drawn product.
Q: What tests accompany the tubes?
Tensile and flattening or bend tests are standard, and eddy-current or hydrostatic testing can be added.
Q: Can the tubes be bent after supply?
They can be bent or coiled for specific exchanger designs when the bend radius and any post-bend heat treatment are agreed in advance.
