1.nominal size: the nominal size specified in the standard. It is the ideal size that the users and manufacturers hope to obtain, and also the order size specified in the contract.
2.actual size: the actual size obtained during production, which is usually greater than or less than the nominal size. This is larger or smaller than the nominal size of the phenomenon known as deviation.
3.m weight: =0.02466* per meter, wall thickness * (OD - wall thickness)