According to ASTM specifications, this particular specification pertains to seamless ferritic and austenitic steel tubes for use in boilers, superheaters, and heat exchangers. The specific grades covered by this specification include T5, TP304, and others listed in Tables 1 and 2. The tubing size ranges from an internal diameter of 1/8 inch up to an outer diameter of 5 inches, with thicknesses ranging from 0.015 to 0.500 inches (0.4 mm to 12.7 mm). If other sizes are required, they can be specified as part of the order, along with minimum and average thicknesses.