ASTM A179 Seamless Cold Drawn Steel Tube for Heat Exchangers

ASTM A179/A179M seamless cold-drawn low-carbon steel tube is specifically manufactured for tubular heat exchangers, condensers, and similar heat-transfer equipment. The specification applies to minimum-wall-thickness seamless tubes produced by cold drawing, with an outside diameter range of 3.2–76.2 mm. After the final cold-drawing operation, the tubes are heat treated at not less than 650°C to obtain controlled hardness, ductility, and dimensional stability suitable for tube-sheet expansion and long-term heat-transfer service. ASTM lists ASTM A179/A179M-24 as the current active edition. 

Specifications

The dimensional tolerances above correspond to common ASTM A179/A450 cold-finished tube requirements. ASTM A450/A450M establishes general requirements applicable to ASTM A179 tubes. 

Main Features

1. Minimum-Wall Design

ASTM A179 is specified on a minimum-wall-thickness basis rather than an average-wall basis. For cold-finished seamless tubes, the commonly applied wall tolerance is +20% / −0% for tubes up to 38.1 mm OD and +22% / −0% above 38.1 mm OD. This is particularly important when the minimum remaining wall controls design pressure or corrosion allowance.

2. Controlled Low-Carbon Chemistry

Carbon is controlled at 0.06–0.18% and manganese at 0.27–0.63%, with phosphorus and sulfur each limited to 0.035% maximum. The low carbon level supports cold drawing, tube-end forming, and tube-to-tubesheet expansion.

3. Defined Mechanical Requirements

Typical ASTM A179 requirements are:

• Tensile strength: ≥325 MPa
• Yield strength: ≥180 MPa
• Elongation: ≥35%
• Rockwell hardness: ≤72 HRB

The relatively low maximum hardness is particularly useful where tubes are mechanically expanded into tubesheet holes.

4. Cold-Drawn Dimensional Control

Cold drawing provides tighter OD control and improved dimensional consistency compared with ordinary hot-finished tubing. For example, tubes below 25.4 mm OD have a typical permissible OD variation of ±0.10 mm.

5. Mandatory Final Heat Treatment

After the final cold-drawing pass, ASTM A179 tubing is heat treated at 650°C or above. This reduces cold-working effects and restores the ductility required for flattening, flaring, and tube-end expansion. 

Our Advantages

1. How Can Minimum Wall Thickness Be Controlled for Heat Exchanger Design?

Heat-exchanger purchasers frequently specify a minimum wall because localized under-thickness can affect pressure integrity and tube service life.

ASTM A179 tubes can be supplied with dimensional inspection based on minimum-wall requirements rather than nominal-wall averages. Wall thickness can be checked at multiple circumferential positions, with the applicable ASTM tolerance of −0% used as the acceptance basis where required. OD and wall inspection records can also be included in the manufacturing documentation.

2. How Can Tube-to-Tubesheet Expansion Problems Be Reduced?

Excessive hardness or inconsistent heat treatment may cause splitting, poor expansion, or unstable tube-to-tubesheet joints.

ASTM A179 limits hardness to 72 HRB, while final heat treatment at 650°C or above restores ductility after cold drawing. Tube ends can additionally be supplied clean, square-cut, and free from heavy scale to support mechanical rolling, hydraulic expansion, or subsequent welding procedures.

3. How Is Tube Integrity Verified Before Installation?

Small discontinuities can become leak paths after tubes are installed in a heat exchanger, making pre-installation inspection important.

ASTM A179 tubing is supplied subject to the applicable ASTM A450/A450M general requirements. Depending on the purchase specification, hydrostatic testing or permitted nondestructive electric examination can be used for tube-integrity verification. Flattening, flaring, flange, and hardness examinations provide additional verification of manufacturing quality and forming behavior. 

Execution Standards

These standards serve similar industrial sectors but are not automatically interchangeable. Chemical composition, dimensions, wall definition, heat treatment, mechanical properties, and inspection requirements must be checked against the actual project specification before substitution.

Application

Shell-and-Tube Oil Cooler

ASTM A179 seamless cold-drawn tubes are suitable for the tube bundle of a shell-and-tube lubricating-oil cooler, where cooling water passes through the tubes while lubricating oil flows on the shell side.

A typical tube specification may be:

19.05 mm OD × 2.11 mm minimum wall × 6000 mm length, ASTM A179/A179M, seamless cold drawn, heat treated, plain end.

The controlled outside diameter supports accurate insertion through baffle plates, while the specified hardness and elongation are suitable for mechanically expanding the tube ends into carbon-steel tubesheets.

Chemical Composition

ASTM A179 itself does not contain five steel grades. It defines one low-carbon material chemistry. For engineering reference, the table below therefore includes ASTM A179 and four commonly compared international low-carbon tube materials. They should not be treated as direct equivalents without engineering review.

Mechanical Properties

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