ASME is the registered trademark of the American Society of Mechanical Engineers.

Scope: This standard covers the standardization of dimensions of welded and seamless wrought steel pipe for high or low temperatures and pressures. This word pipe is used as distinguished from tube to apply to tubular products of dimensions commonly used for pipeline and piping systems.

The size of all pipe is identified by the nominal pipe size.

The manufacture of pipe NPS 1/8 (DN 6) to NPS 12( DN 300) inclusive is based on a standardized outside diameter (OD). This OD was originally selected so that pipe with a standard OD and having a wall thickness that was typical of the period would have an inside diameter(ID) approximately equal to the nominal size.

Athough there is no such relation between the existing standard thickness–OD and nominal size — these nominal sizes and standard ODs continue in use as”standard”.

Marerials

The dimensional standards for pipe described here are for products covered in ASTM specifications.