Grade of steel used
Carbon steel pipe comes in a variety of grades and strengths, as well as wall thicknesses. As we have seen, the allowable stress is used to determine the required wall thickness. Hence, the allowable stress is determined by both the material’s metallurgy and the manufacturing method.
ASTM & API
Other than that, the various ASTM and API piping specifications provide guidelines for both metallurgy and manufacturing method. For example, ASTM Specifications A-53 and A-106, as well as API Standard 5L, are the most widely used piping specifications for process lines.
Schedules
Also, the primary wall thicknesses used are defined by schedules, such as Schedule 40, and weights, such as STD. In Grades A and B, ASTM A53 and ASTM A106 pipe are fabricated SMLS or seamed by electric resistance welding. However, tensile strength is higher in grades B. Besides that, ASTM A106 is available in three grades, A, B, and C, in descending order of tensile strength.