A–B–C–D–E–F–G–H–I–J–K–L–M–N–O–P–Q–R–S–T–U–V–W–X–Y
NACE International
A professional organization for the corrosion control industry established in 1943 which publishes papers articles and standards on all aspects of corrosion and has written the definitive standard for valve materials for sour gas service. Formerly known as the National Association of Corrosion Engineers. www.nace.org
National Pipe Thread
A US standard for tapered (NPT) or straight (NPS) threads used to join pipes and fittings.
NEC
An American consensus standard for the installation of electrical systems.
Needle Valve
A type of small valve used for flow metering having a tapered needlepoint plug or closure element and a seat having a small orifice.
NEMA
National Electrical Manufacturers standard American
Nipple
A short length of small size pipe threaded on both ends. Used on end connections of screwed-end valves and in small size piping systems.
Non Destructive Tests
Those inspection tests which are not destructive to the product structure or function. See RT (Radiographic Test), Liquid Penetrant Test, Magnetic Particle Test and Ultrasonic Test.
Non Rising Stem
A gate valve having its stem threaded into the gate. As the stem turns, the gate moves but the stem does not rise. Stem threads are exposed to line fluids.
Normally Closed Solenoid Valve
An electrically operated valve whose inlet orifice is closed when the solenoid coil is not energized. Energize to open. See Solenoid.
Normally Open Solenoid Valve
An electrically operated valve whose inlet orifice is open when the solenoid coil is not energized. Energize to close. See Solenoid.
NPS (Nominal Pipe Size)
Numerical inches designation of size which is common to components in piping systems of any one size. The nominal pipe size is designated by the letters NPS followed by a number. See also National Pipe Thread and API 6D / ISO 14313.
NPT
American National Pipe Thread standard for tapered threads.