We’ve also created our own for you to download Pdf documents using the links below. If you Google ‘Pipe Size Charts’, you’ll find plenty of pipe manufacturers who offer these to download from their website. What this means is that sizes (NPS) ⅛″ up to 12″ have an outside diameter that is greater than its nominal pipe size, whereas pipe sizes 14″ and above have an outside diameter equal to its nominal pipe size. Just when you thought you were beginning to understand pipe sizing unfortunately there’s an added complexity to be aware of:ĭifferent sizes of pipes are manufactured in different ways and this has affected how pipe sizing works. Less wall thickness is required to withstand the same pressure as compared with other steels.

The reason stainless steel is schedules are treated in this way is due to their extra strength. An example to illustrate is an NPS 14 pipe with a schedule of 40s shown in the table below. So somebody specifying a pipe for a high pressure application will select a bigger number which represents a bigger schedule (wall thickness).Īdditionally, in the case of stainless steel, piping schedules are specified with a letter ‘s’ as a suffix after the number. Two pipes the same diameter may have different schedules, which means they have a different wall thickness. It is not an actual measurement, but a guide number based on a wall thickness formula. Pipe schedule (SCH) is how the wall thickness of a pipe is described. (To convert from NPS 6 to DIN simply multiply the 6 x 25=150. For example the metric equivalent of an NPS 6 pipe (6”) is DN 150. This is the international and European metric method used to describe NPS (or NB).ĭN pipe sizes numbers are therefore different to NPS.

( It is a common way of describing pipe sizes used in the USA). ‘NPS’ is an abbreviation of Nominal Pipe Size, which is a term used as a guideline number defining the diameter of the pipe. So what exactly does NPS mean? Is it the inside diameter, the outside diameter? or the wall thickness? There’s not a huge amount to remember, but you do need to familiarize yourself with the terminology and the underlying methods behind how pipes are classified by manufacturers in the oil and gas sector. If you are new to the world of in-situ machining one of the essential things you must learn is how pipe sizing works.

Smith chart turbine varying diameter