Terms starting with N

Planning rule that a grid must stay within limits after losing any single major element such as a line or generator.

The point on the seabed directly beneath the sonar, where the beam looks straight down.

The unimaged strip directly under a side-scan towfish, roughly twice as wide as the fish's height above the seabed.

Linemen's nickname for inside electricians, implying they never climb poles or haul heavy line gear. Shop talk

Potential of a buried or immersed structure before any cathodic protection current is applied.

A map of waters and coasts made for mariners, showing depths, hazards, aids to navigation and landmarks.

Shorthand for the vessel's positioning data stream, or for the positioning system as a whole. Shop talk

North American Vertical Datum: the geodetic height reference used for land elevations across the United States.

N design: the number of gyrations a mix specimen gets in the gyratory compactor, set by expected traffic.

A tide of smaller than average range, occurring near first and last quarter moon when Sun and Moon pull at right angles.

Stranded after grounding near spring high water and unable to refloat until the next spring tides return. Shop talk

Blast grade allowing light shadows or stains on no more than 5 percent of the surface, the usual immersion standard.

Describes a bolt visibly thinner in one spot because it was stretched past yield and started to neck. Shop talk

Machine that drives boards of barbed needles through a moving batt to bond it mechanically.

A small valve with a long tapered stem tip that meters tiny flows with fine adjustment.

Mechanical bonding in which barbed needles punch repeatedly through a batt, dragging fibers through and tangling it.

Non-evaporable getter: a porous alloy that pumps active gases once it has been activated by heating in vacuum.

The interior face of a wall or slab, opposite the water, where waterproofing must resist water pushing it off.

Small, tight knot of tangled fibers that shows as a speck or pimple on the fabric surface.

List of every electrical connection in a design, naming which pins belong to which net.

Nickel-aluminum composite that reacts in the flame to give a strongly bonded first layer.

Shop name for a 90-degree conduit bend, whether factory-made or bent on site. Shop talk

Short length of conduit, threaded or with fittings on both ends, connecting two nearby boxes or enclosures.

A short length of pipe, threaded or plain on its ends, used to connect two fittings or a valve to a fitting.

A common label phrase claiming a measurement links back to US national standards, often used loosely. Shop talk

An informal but widely used name for one candela per square meter, the unit of luminance.

An etch of nitric acid in alcohol that reveals steel microstructure and grinding damage.

A low-temperature surface hardening that diffuses nitrogen into alloy steel gears with almost no distortion.

Diffusing nitrogen into steel below its critical temperature to form a hard case with no quench.

Number from 000 to 6 describing grease stiffness, based on cone penetration after working.

Nominal maximum aggregate size: the sieve size used to name a mix, such as a 9.5 mm or 19 mm mix.

National metrology institute, the body that realizes a country's measurement units at the top of its traceability chain.

Antioxidant joint compound brushed onto aluminium wire before it goes under a lug, named after a common brand. Shop talk

The 18.6-year cycle in the tilt of the Moon's orbit that slowly raises and lowers tidal ranges.

The stated target size of a feature before any tolerance is applied.

Air, nitrogen or other gases trapped in a refrigeration system that will not condense at operating conditions.

Describing a sealant thick enough to stay in vertical and overhead joints without slumping.

Fabric made directly from fibers or filaments locked together by needles, water jets, heat or binder instead of woven or knitted yarn.

Geotextile made by needlepunching or heat-bonding fibers into a felt-like sheet, used for filtration, drainage and cushioning.

The bell-shaped distribution assumed for most certificate values and averaged readings, set by mean and standard deviation.

Symmetric bell-shaped distribution set by a mean and a standard deviation, the default model for measurement data.

Heating steel above its upper critical temperature and cooling it in still air to refine and even out grain.

An official bulletin of chart corrections and navigational warnings, issued regularly to keep charts current.

The precision tip on an oil burner that atomizes oil into a fine cone-shaped spray, rated in gallons per hour.

In a plasma gun, the water-cooled copper anode the arc attaches to; in HVOF, the passage that shapes the jet.

Operator who handles the gunning nozzle and controls water and placement on a gunning or shotcrete crew. Shop talk

National Pipe Taper: the tapered pipe thread used for threaded valves and fittings in North America.

A portable instrument with a radioactive source that estimates asphalt density in about a minute without cutting a core.

A safety shutdown or lockout caused by a faulty or marginal device, not by a real unsafe condition. Shop talk

Protective device opening with no real fault present, usually from bad settings, leakage or transients. Shop talk

Slang for someone trained to operate or maintain nuclear reactors, especially a naval nuclear sailor. Shop talk

A measure of how wide a cone of light a fiber can accept and guide, written as a number such as 0.20.

An internally threaded part that mates with a bolt or stud, graded so the bolt breaks before the nut strips.

The empirical constant K in T = KDF that lumps all the friction and geometry between torque and tension.

A powered tightening spindle, handheld or fixtured, that drives nuts and bolts to a controlled torque or angle.

Shop name for a nylon-insert lock nut, the hex nut with a colored plastic ring captured in one end. Shop talk