What Is SA-179 / ASTM A179 Material?
SA-179 is the ASME designation for the material defined by ASTM A179/A179M, a specification for seamless cold-drawn low-carbon steel tubes for heat exchangers and condensers. The same product is commonly called A179, ASTM A179 tube or SA-179 tube. It is a mild steel tube with high ductility, good weldability and consistent quality, produced by cold drawing to precise dimensions.
Chemical Composition
The composition is controlled to keep the steel soft, ductile and weldable. Typical limits are carbon 0.06-0.18%, manganese 0.27-0.63%, phosphorus 0.035% max and sulfur 0.035% max.
| Element | Limit (%) |
|---|---|
| Carbon (C) | 0.06 - 0.18 |
| Manganese (Mn) | 0.27 - 0.63 |
| Phosphorus (P) | 0.035 max |
| Sulfur (S) | 0.035 max |
Mechanical Properties
Per the standard, the minimum tensile strength is 325 MPa, the minimum yield strength is 180 MPa, and the minimum elongation is 35%. The material is also checked by flattening, flaring and hydrostatic tests to confirm its suitability for tube expansion into tube sheets.
| Property | Minimum Value |
|---|---|
| Tensile strength | 325 MPa |
| Yield strength | 180 MPa |
| Elongation | 35% |
Manufacturing Process
A179 tubes are made by cold drawing seamless pipe to the final size, which provides a smooth bright surface, accurate outside diameter and uniform wall thickness. After drawing, the tubes may be annealed to restore ductility, and are straightened and cut to length. Each tube is subject to nondestructive testing or hydrostatic testing and dimensional inspection before shipment.
Applications
SA-179 tubes are used in tubular heat exchangers, condensers, coolers and similar heat transfer equipment in refineries, power plants, chemical plants and marine systems. Typical services include cooling water, steam and process fluids that are not corrosive to carbon steel. Tubes are normally expanded or welded into tube sheets and can be bent for U-tube bundles.
SA-179 vs A179
SA-179 is the ASME Boiler and Pressure Vessel Code designation, which refers to the same material as ASTM A179. In practice, A179 and SA-179 tubes are interchangeable when the ASTM and ASME editions are harmonized, which is the case for this specification. Purchasers should confirm which designation is required by their project code.
FAQ About SA-179 Material
Is SA-179 tube seamless or welded?
SA-179 per ASTM A179 is a seamless tube, produced by cold drawing a pierced hollow.
What is the difference between SA-179 and SA-106?
SA-106 is a hot-finished carbon steel pipe for high-temperature service and is much larger in size; SA-179 is a small-diameter cold-drawn tube specifically for heat exchanger and condenser service.
Can A179 tubes be bent into U-tubes?
Yes. The low carbon content and ductility allow cold bending into U-tubes, followed by stress relief where required by the design code.
What heat treatment is applied?
Tubes are normally supplied in the annealed or normalized condition as required, to ensure ductility and stable mechanical properties for tube rolling.
What tests are required?
Typical tests include tensile testing, flattening, flaring, hydrostatic or nondestructive testing, and dimensional checks, per ASTM A179/A179M.
What size range is typical?
A179 tubes are typically small-diameter, commonly from about 3/4 inch (19 mm) outside diameter and up to 3 inches (76 mm) outside diameter, with wall thicknesses suited to heat exchanger duty.