Terms starting with G

The head of the lighting and electrical department on a film or television set. Shop talk

A clamp or screw fitted to a safety valve to hold its disc shut during a system pressure test.

Length saved because conduit turns around a curve instead of a sharp corner, used when cutting pipe to length.

The material inside a laser or amplifier that amplifies light once it is pumped: a crystal, glass, gas, semiconductor or doped fiber.

The drop in an amplifier's gain as the signal grows strong enough to deplete the stored inversion.

A splice that shows an apparent gain of light on an OTDR trace, an artifact of mismatched backscatter. Shop talk

Adhesive wear where thread surfaces cold-weld and tear under load, seizing a nut partway down a bolt.

Severe adhesive wear where sliding metals seize and tear, raising lumps of transferred metal.

Severe adhesive wear where loaded metal surfaces slide, cold-weld together and tear material out.

Large, slow vertical swinging of overhead line conductors driven by wind on ice-coated wires.

Accelerated corrosion of the more active metal when two dissimilar metals touch in a shared electrolyte.

Ranking of real metals and alloys by their measured potential in a given electrolyte, usually seawater.

A railroad track worker, especially one on a section or tie gang doing hands-on track work. Shop talk

Big lockable steel chest that holds a crew's tools and material on a jobsite overnight. Shop talk

The ability of an adhesive to bond parts with a loose or uneven fit and still cure fully across the gap.

Shop name for an oxy-fuel cutting torch, also used for heating seized parts. Shop talk

Controlled bleed of air into an oil-sealed pump's compression stage that keeps vapours from condensing in the oil.

Multiplier that converts a gauge reading calibrated for nitrogen into the true pressure of another gas.

Total gas flow a pumping system must remove, summed from process gas, leaks, outgassing and permeation.

The string of valves, regulator and switches that controls and safeguards gas on its way to the burner.

Describing a casting, galvanized part or batch of metal known to outgas and ruin the finish. Shop talk

Full-bore valve with a sliding plate that isolates a high vacuum pump or a load lock from the chamber.

A multi-turn isolation valve that lifts a flat or wedge-shaped gate clear of the flow path to open.

The distance between the inside faces of the two rails, 4 feet 8.5 inches on standard-gauge track.

The glass tube or window on a steam boiler that shows the operator the actual water level.

Study that measures how much observed variation comes from the measurement system's repeatability and reproducibility.

The manifold gauge set techs connect to service ports to read system pressures, saturation temperatures and charge. Shop talk

A beam whose intensity falls off from the center as a bell curve, the shape of an ideal single-mode laser.

Geosynthetic clay liner: a factory-made barrier of sodium bentonite held between two geotextiles.

Shop name for a gear measuring machine that traces profile, helix, pitch and runout, and for its operator. Shop talk

Finishing hardened gear teeth with abrasive wheels to correct heat treat distortion and reach high accuracy.

The number of teeth on the driven gear divided by those on the driver, setting speed reduction and torque gain.

Cutting gear teeth with a reciprocating, gear-shaped cutter that rolls with the blank as it strokes.

A compact gear reducer that bolts to a motor face, and also a person who lives for machinery. Shop talk

A sheet of colored or diffusing plastic film placed in front of a lighting fixture to change its color or quality. Shop talk

How many seconds a powder takes at a set temperature to go from melted to a rubbery gel that no longer flows.

Single-gang metal device box with removable sides, so several can be ganged together for a row of switches. Shop talk

Three-dimensional honeycomb of welded polymer strips that is stretched open on site and filled with soil, stone or concrete.

Product that combines two or more geosynthetics, most often a geonet core with geotextile bonded on one or both sides.

Polymer grid with large open apertures that interlocks with soil or aggregate to reinforce or stabilize it.

Low-permeability polymer sheet used as a liquid or gas barrier in liners, covers, ponds and tunnels.

Net of extruded polyethylene ribs that forms a thin, high-flow drainage layer within its own plane.

Polymer sheet, grid, net or cell product built into soil or rock to separate, filter, drain, reinforce or contain it.

Permeable fabric used with soil to separate, filter, drain, reinforce or protect, made woven, nonwoven or knitted.

Standard file format describing each board layer as a 2D image, sent to the fabricator to build the board.

To take an electric shock on the job, as in got bit by a hot neutral. Shop talk

Reactive material that removes gas from a vacuum by binding it chemically to a fresh metal surface.

A false event on an OTDR trace caused by a strong reflection bouncing back and forth in the fiber.

A weak stray beam from a back-surface reflection that travels off in an unexpected direction or focuses somewhere it should not. Shop talk

A gear noise tone that matches no tooth count in the box, left behind by errors in the cutting machine.

A single bare lamp on a stand left burning center stage whenever a theater is dark and empty. Shop talk

A faint glow from LED fixtures that are switched off, caused by small leakage currents in the wiring or controls. Shop talk

The coupling heads on the ends of air brake hoses, which lock together when two cars are joined. Shop talk

The part that presses down on the packing to load it against the stem, adjusted by the gland nuts.

Visual discomfort or loss of visibility caused by excessive brightness or contrast in the field of view.

Installer shorthand for optical fiber itself, or for the fiber plant as a whole. Shop talk

Fully hardened and untempered, so hard and brittle that a file skates off and a drop could shatter it. Shop talk

The temperature change of a refrigerant blend as it boils or condenses at constant pressure.

A brief, bright reflection of a laser beam off a shiny object such as a tool, screw head, mount or jewelry. Shop talk

Visible sparkling metal flakes in drained oil or a cut-open filter, a red flag for serious wear. Shop talk

A linear-motion valve that throttles well because its disc moves straight onto a seat across an S-shaped flow path.

The mirror-like shine of a paper or print surface, measured as specular reflectance at a defined angle.

How mirror-like a finish is, read with a gloss meter at a fixed angle, usually 60 degrees.

Black absorbing port in an integrating sphere that removes mirror-like surface reflection from a measurement.

Slang for an itinerant contract worker who travels from plant to plant working refuelling outages. Shop talk

The everyday word for any adhesive, used freely on the floor but avoided in engineering drawings. Shop talk

Lab slang for a bond test where the epoxy broke first, so the coating is at least as strong as the glue. Shop talk

The stage of assembly where all parts get adhesive and are clamped together, or the clamped assembly itself. Shop talk

Gas metal arc welding: a continuously fed wire electrode shielded by gas, known in the shop as MIG.

Gear mesh frequency: tooth count times shaft speed, the frequency at which teeth enter mesh.

Maximum specific gravity of the mix: the density it would have if every air void were squeezed out.

Clean shop term for a tiny, unmeasured amount, smaller than anyone bothers to put a number on. Shop talk

Global navigation satellite systems: satellite positioning such as GPS, GLONASS, Galileo and BeiDou, used together.

A fixed gauge with one end that must fit and one that must not, for fast pass or fail checks.

A yard switch engine, the locomotive that spends its life sorting cars around a terminal. Shop talk

A thin metal or glass disk with a cut pattern, placed in a spotlight to project shapes, textures or logos. Shop talk

Lab shorthand for laser safety eyewear, the filtering glasses or goggles rated by optical density at specific wavelengths. Shop talk

Hard-gold-plated contacts along a board edge that plug into a slot, as on a memory module.

Slang for an exceptionally skilled welder whose work passes inspection every time. Shop talk

Known-good assembled board kept as the reference for testing, comparing and debugging others. Shop talk

A known-good, carefully characterized example of a product kept to check test stations and fixtures. Shop talk

Reference wafer or part kept aside and measured on a schedule to check that a tool or gauge has not drifted. Shop talk

The final tie-in weld between new and existing piping that cannot be included in the hydrotest. Shop talk

An instrument that measures a luminaire's light intensity in every direction by turning the luminaire, or a mirror around it, relative to a detector.

The imaginary visitor who brings last-minute changes and bright ideas nobody thought through. Shop talk

Oversized cover plate used to hide a drywall hole cut too big or too ragged around a box. Shop talk

Box extension ring that brings a box set too deep back out flush with the finished wall surface. Shop talk

A personal project made on company machines and material, on the side or on the clock. Shop talk

Shop slang for the part that goes into another part, from the phrase goes into. Shop talk

Floor word for how quickly and firmly an adhesive takes hold when parts are pressed together. Shop talk

Index tensile test on geotextiles in which a 100 mm wide specimen is gripped by 25 mm jaws in its middle.

Tensile test in which jaws narrower than the specimen grip its center, so neighboring fibers help carry the load.

The distribution of particle sizes in an aggregate blend, reported as percent passing each sieve.

Shop shorthand for the strongest common inch bolt, and loosely for anything overbuilt; six lines on the head. Shop talk

Switching a paper machine from one product to another while it keeps running. Shop talk

Laboratory ratio that shows whether a soil and geotextile pair is starting to clog under steady seepage.

The main direction in which fibers in a paper sheet are aligned, almost always the machine direction.

The average size of the crystals in a metal, usually reported as an ASTM number where higher means finer.

Mass of paper per unit area in grams per square meter, the base for most optical calculations.

Shop name for an extra-low first gear used for crawling under heavy load, not for normal driving. Shop talk

The SI unit of absorbed dose, equal to one joule of energy deposited per kilogram.

Lighting a surface from a very steep angle, close to the wall, to bring out its texture with strong highlights and shadows.

Semi-solid lubricant made of oil held in a thickener sponge, usually with additives.

Whether two greases can be mixed without losing consistency, dropping point or stability.

Slang, sometimes fond and sometimes dismissive, for a mechanic or whoever is stuck with grease duty. Shop talk

Shop word for a gear in its soft, machined state before heat treatment, as in cut green, finish hard. Shop talk

Describes refractory that has been formed or placed but not yet fired, dried or heated in service.

Epoxy-coated rebar, named for its usual green coating, used where salt and chlorides threaten corrosion. Shop talk

Concrete that has set but is only hours or days old, still weak enough to cut, mark or damage easily. Shop talk

The hold a bonded joint has in its first seconds or minutes, long before the adhesive reaches full cure.

Flexible metal conduit: spiral-wound steel or aluminium tube that wire is pulled into, used for short flexible runs. Shop talk

The greenish cast a sheet takes on when optical brightener is dosed past its effective range. Shop talk

Shop slang for a gearbox or axle destroying itself all at once, scattering broken teeth and bearing parts. Shop talk

Turning millions of scattered soundings into a regular grid of depth values at a chosen cell size.

Heat damage to hardened gear teeth from aggressive grinding, which softens or rehardens the surface.

Extra coating thickness sprayed beyond the final size so it can be ground or machined to finish.

Shop saying that a grinder and paint make me the welder I ain't, for hiding ugly welds. Shop talk

Lightly abrading geomembrane before an extrusion weld to remove the oxidized surface and dirt.

Heat damage to a hardened surface from abusive grinding, which softens it or creates brittle rehardened spots.

Shop blend of grip and traction for how well something holds on, from vise jaws to boot soles. Shop talk

Blasting a surface with angular abrasive to clean it and roughen it so the coating can grip.

Pre-fired clay or crushed brick added as aggregate to cut shrinkage and cracking in refractory bodies.

A weld made in a prepared opening between two members, such as a beveled butt joint.

Leak big enough to stop a system pumping down properly, or to be found without sensitive instruments.

The electrical path from the part through hooks, racks and conveyor to earth that lets charged powder stick.

Shop word for the work lead and its clamp, which completes the welding circuit through the part. Shop talk

Unintended current path formed when connected equipment is earthed at points of different potential.

Large continuous copper area, usually a whole layer, that serves as ground and as the reference for signals.

Group of impressed-current anodes buried in backfill that discharges rectifier current into the earth.

The increase in a part's size after hardening, caused mainly by austenite turning into bulkier martensite.

Grams per square meter, the shorthand unit for nonwoven basis weight on specs, labels and the line.

Gas tungsten arc welding: an arc from a non-consumable tungsten electrode under inert gas, known as TIG.

A margin that pulls acceptance limits inside the tolerance limits to cut the risk of passing nonconforming items.

Guide to the Expression of Uncertainty in Measurement, the core reference method for evaluating measurement uncertainty.

Describing an adhesive that stayed soft and rubbery instead of curing hard. Shop talk

Installer slang for the hand-held extrusion welder used on patches, boots and detail welds. Shop talk

Booth word for the thermal spray torch itself, whether plasma, HVOF, arc or flame. Shop talk

The arc voltage of a plasma gun, watched as a live indicator of gas mix, power and hardware wear.

Shop name for gunned refractory and the dry-gun process, borrowed from the concrete trade. Shop talk

Spraying refractory through a hose and nozzle with compressed air to build or repair a lining.

Mock-German torque spec meaning tightened by feel until it seems good and tight, with no wrench reading. Shop talk

Interior of a panel: the bus bars, breaker mounting and neutral assembly that bolt into the enclosure. Shop talk

Sheet-metal trough with a removable cover used to splice, tap and route conductors next to panels and disconnects. Shop talk

The tradespeople actually doing the hands-on work, as opposed to supervisors, planners and office staff. Shop talk

Group Velocity Dispersion: how strongly a material's group velocity changes with wavelength, which stretches short pulses.

The lab machine that compacts mix specimens by pressing and tilting them in a rotating mold.