𝗡𝗣𝗦 (𝗡𝗼𝗺𝗶𝗻𝗮𝗹 𝗣𝗶𝗽𝗲 𝗦𝗶𝘇𝗲) is an international definition for measuring pipe size and schedule for various pressures and temperatures.
𝙄𝙨 𝙉𝙋𝙎 𝙙𝙞𝙧𝙚𝙘𝙩𝙡𝙮 𝙧𝙚𝙡𝙖𝙩𝙚𝙙 𝙩𝙤 𝙊𝘿 𝙤𝙛 𝙩𝙝𝙚 𝙥𝙞𝙥𝙚?
𝘛𝘩𝘦 𝘢𝘯𝘴𝘸𝘦𝘳 𝘪𝘴; 𝘪𝘵 𝘥𝘦𝘱𝘦𝘯𝘥𝘴 𝘰𝘯 𝘕𝘗𝘚 size.
For example; NPS 14 pipe will have an outside diameter of exactly 14 inches while for smaller pipes of NPS 1/8 up to NPS 12, the NPS number does not directly represent the outer diameter of the pipe. For example, an NPS 12 pipe will have an actual outside diameter of 12.75 inches.