scope:

This specification² covers minimum wall-thickness, seamless carbon steel boiler and superheater tubes for high-pressure service.

The tubing sizes and thicknesses usually furnished to this specification are 1/2 in. to 7 in. (12.7 to 177.8 mm) outside diameter and 0.085 to 1.000 in. (2.16 to 25.4 mm), inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of this specification.

Mechanical property requirements do not apply to tubing smaller than ¹/₈ in. (3.2 mm) inside diameter or 0.015 in. (0.38 mm) thickness.

When these products are to be used in applications conforming to ISO Recommendations for Boiler Construction, the requirements of Specification A 520 shall supplement and supersede the requirements of this specification.

The values stated in inch-pound units are to be regarded as the standard.

² For ASME Boiler and Pressure Vessel Code applications