What is the tolerance of ASTM A179 steel pipe?

The tolerance of ASTM A179 steel pipe is defined in the standard for seamless cold-drawn carbon steel heat exchanger and condenser tubes. ASTM A179 specifies the mechanical properties, chemical composition, and dimensions of the pipes, including the allowable tolerances. These tolerances are important to ensure the pipes fit within the required specifications for various applications, such as in heat exchangers, condensers, and other fluid or gas transportation systems.

Key Tolerances for ASTM A179 Steel Pipe:

1. Outside Diameter (OD) Tolerance:
- For seamless tubes, the outside diameter tolerance typically falls within ±0.5 mm for pipes up to 25 mm in diameter.
- For pipes with larger diameters, the tolerance may be specified more precisely based on the pipe's size and the manufacturer’s processes.

2. Wall Thickness Tolerance:
- The wall thickness tolerance is usually specified as ±10% of the nominal thickness. For example, if the nominal wall thickness is 5 mm, the actual thickness can range from 4.5 mm to 5.5 mm.

3. Length Tolerance:
- The standard length tolerance is typically +0/-5 mm for lengths up to a certain size (often 6 meters or more). The pipe can be slightly longer than the specified length but should not be shorter.

4. Ovality Tolerance (Shape Deviation):
- The ovality (difference in the major and minor diameters) of the pipe should not exceed 2% of the nominal diameter. This ensures the pipe maintains a circular cross-section and fits correctly into fittings and connectors.

5. Straightness Tolerance:
- Straightness tolerance is typically specified as a deviation from a straight line, usually limited to 1 in 1000 of the length. This means the pipe should not deviate more than 1 mm per meter of length.

6. Surface Finish and Other Dimensions:
- The surface finish of the pipe, while not directly part of the dimensional tolerance, is often required to meet specific surface quality standards, such as smoothness without visible defects, in line with ASTM A179 requirements.

Summary:
The tolerance for ASTM A179 steel pipe includes allowances for variations in diameter, wall thickness, length, ovality, and straightness. These tolerances ensure that the pipes conform to specified dimensions while maintaining the strength, performance, and fit needed for use in applications like heat exchangers and condensers. Depending on the pipe size and manufacturer, these tolerances can vary slightly, but they typically fall within these general guidelines.