TThis standard establishes methodology consistent with industry best practices for the measurement, analysis, and correction of alignment of shafts on rotating machinery coupled by means of a flexible coupling where such shafts are supported by two bearings in independent, horizontally mounted machine cases. Electric motors driving a pump, fan, or similar machine are examples of this type of machinery. Rigidly coupled machines are outside of the scope of Part 1 of this standard. The methodology addresses conditions for machinery mounting which directly affects shaft alignment, methods for measuring the amount of shaft misalignment, and practices for relocating machine cases to achieve proper shaft alignment. Tolerances are provided in a system of Alignment Quality Grades. Ancillary information for shaft alignment is provided in eight Annexes. Part 2 of this standard provides definitions of terminology unique to the alignment of machinery that has been in common use among engineers and technicians working in the field.