A unit of PIPE size (NPS, DN, STD, SCH, etc.)

 

 

♣ NPS&DN

 

- NPS: Norminal Pipe Size with inch

- DN: Diameter Norminal with ISO metric unit system

 

 

 

→ Norminal Pipe Size (NPS) is a North American set of standard sizes for pipes. The European and international designation equivalent to NPS is DN, in which sizes are measured in millimetres. The term NB (Nominal Bore) is also frequently used interchangeably with NPS.

 

→ Over 14" = Same as outer diameter. i.e. just different unit, have no physical meaning

 

→ No problem between the units with coversion well

 

→ Many international Code and standard mention a table for conversion

 

 

NPS 1 = DN 25 = 1 inch

 

 

ANSI/ASME: NPS, DN

API: INCH, DN

EU/ISO: DN

 

 

 

 

 

 

♣ PIPE WALL THICKNESS

 

- Weight System: ASME and ASTM define STD(standard), EX(extra strong), XXS(double extra strong), Manufacturues' weight, etc.

 

- Schedule(SCH) = (Operating pressure/Maximum allowable strss) x 1,000

→  5, 5S, 10, 10S, 20, 20S, 30, 40, 40S, 60, 80, 80S, 100, 120, ...

("S" is for stainless steel pipe defined in ANSI)

 

- API Specification: Definition of thickness for each size in API 5L, 5LX, etc. i.e. Find API Table

 

- IPS: Iron Pipe Size