Terms starting with I

Individuals and moving range chart: the control chart for one measurement per period, such as one batch or one lot.

Indoor air quality: how clean and healthy indoor air is, judged by contaminants, ventilation, humidity and comfort.

Impressed current cathodic protection: CP powered by a rectifier pushing current through long-life anodes.

Describes an evaporator coil or suction line coated in ice because it is running below freezing. Shop talk

Slang for drips of excess root metal hanging inside a pipe from too much heat or too wide a gap. Shop talk

Slang for the sticky petroleum gel that fills loose buffer tubes and some cable cores to keep water out. Shop talk

Shop name for connectors and tools from the maker whose Wire-Nut trademark became a generic word. Shop talk

A gear placed between a driver and a driven gear to change direction or span distance, without changing ratio.

Inverse definite minimum time: an overcurrent curve that trips faster as current rises, down to a set minimum.

A standard text file of a luminaire's measured candela distribution, loaded into lighting calculation software.

Insulating firebrick: light, porous brick rated by the maximum temperature it can face, such as group 23 or 26.

A furnace that burns the binder out of a mix sample to measure binder content by weight loss.

Insulating glass unit, two or more lites sealed around a spacer with a dry air or gas space between.

In-line inspection: sending instrumented tools through a pipeline to measure wall loss, dents and cracks.

The amount of light falling on a surface per unit area, measured in lux or foot-candles.

A handheld meter that reads the light falling on a surface in lux or foot-candles, commonly called a light meter.

Standard CIE light distribution approximating average daylight, with relatively little ultraviolet.

Standard CIE daylight at about 6500 K, with enough ultraviolet to excite optical brighteners strongly.

A test that drops a weighted punch onto a coated panel and checks whether the film cracks or lifts.

Total opposition a circuit offers to alternating current, combining resistance and reactance, in ohms.

Designing and building traces to a target impedance, such as 50 or 100 ohms, within a set tolerance.

The uncertainty carried into a measurement from the calibration certificate of the reference standard used.

In the siding, waiting for another train to pass on the main line. Shop talk

A root left unfused because the weld never reached all the way through a joint meant to be fully penetrated.

A clear gel with nearly the same refractive index as fiber, used to fill gaps between fiber ends.

To align a vise, part or bore to the machine axes using a dial or test indicator. Shop talk

Hardening gear teeth by heating them locally with an induction coil and quenching immediately.

Heating only the surface of a steel part with an alternating magnetic field, then quenching for a hard case.

Early-life failures caused by manufacturing flaws, giving a failure rate that starts high and then falls.

A short extra line run to fill a gap in coverage, usually to clear holidays found during processing. Shop talk

Outdoor air that sneaks into a building through gaps in its shell, pushed by wind, stack effect and fans rather than by design.

A condition that is not the thing being measured but still changes the reading, such as temperature or humidity.

The point at which fresh concrete stops being workable and begins to stiffen into a solid.

The ability of a paper surface to keep ink and its vehicle on top instead of absorbing them.

Smaller plastic tubing placed inside a larger conduit to divide it into separate protected paths for fiber cables.

Large transient current drawn when a transformer, motor or capacitive load is first switched on.

A small replaceable carbide or ceramic cutting tip clamped in a holder, indexed to a fresh edge when worn.

The optical power lost when a component or a whole link is placed in the light path, measured in dB.

The fiber tech's rule that every connector end face gets scoped, and cleaned if needed, before it is mated. Shop talk

Loss of geosynthetic strength caused by placing, spreading and compacting fill on it.

Structure potential read in the split second after CP current is switched off, free of IR drop.

Lightweight castable made with porous aggregates that trades strength for low thermal conductivity.

Fitting that electrically isolates one pipe section from another so CP current stays where it belongs.

Sizing insulation and surge arresters together so any flashover lands at a cheap, self-restoring point, not inside plant.

DC test that applies a high voltage between conductors and earth and reads leakage resistance in megohms.

A sealed batch furnace with a heating chamber and an attached oil quench, run under protective atmosphere.

A white-lined hollow ball that spreads a source's light evenly so one detector can read its total lumens and color.

Hollow sphere lined with a highly reflective matte white that bathes a sample in diffuse light from all directions.

Situation where the effect of one factor depends on the level of another, so their combined effect is not simply additive.

The handoff of cars from one railroad to another at an agreed junction track or yard.

Shear resistance between a geosynthetic and soil, or between two geosynthetics, that keeps lined slopes from sliding.

Unwanted DC or AC current picked up from another source, which corrodes a structure where it leaves.

Attack that runs along grain boundaries, often in stainless steel sensitized by welding heat.

Precision measured within one lab over longer periods, with changes such as different days, operators or recalibrations.

A gear with teeth cut on the inside of a ring, meshing with a pinion running inside it.

Jokey name for an effect so obvious in a plot that it hits you between the eyes, no formal statistics needed. Shop talk

The temperature of the weld area just before the next pass starts, with minimum and maximum limits.

Timed switch fitted to a rectifier or bond that cycles CP current on and off for instant-off readings.

The rise of sea level under low air pressure and fall under high pressure, about 1 cm per hectopascal.

The rule that illuminance from a point source falls with the square of distance, so double the distance gives a quarter of the light.

The curve traced by the end of a taut string unwound from a circle, the shape of almost every gear tooth flank.

Nitriding with a glow-discharge plasma in a vacuum vessel, which allows close control of the white layer.

Capture pump that ionizes gas in a high-voltage magnetic discharge and buries the ions in titanium.

Gauge that reads high and ultra-high vacuum by ionizing gas molecules and measuring the resulting ion current.

Cleaning a bonding surface with isopropyl alcohol on a lint-free wipe just before adhesive goes on. Shop talk

Reliability class 1, 2 or 3 under IPC standards, setting the acceptance criteria a board is built to.

Integrated part load value: a single weighted chiller efficiency figure that reflects operation at 100, 75, 50 and 25 percent load.

Intrinsically photosensitive retinal ganglion cells: eye cells that sense light for the body clock rather than for vision.

A small card coated with phosphor that glows visibly where an invisible infrared beam hits it, used for alignment. Shop talk

Curing powder with infrared emitters that heat the film and part surface directly by radiation.

Voltage error in a potential reading caused by current flowing through the soil between pipe and electrode.

International Roughness Index: a measure of ride quality in inches per mile, collected with a laser profiler.

The phase map of iron and carbon that shows which structures are stable at each temperature and carbon level.

A thin, amorphous phosphate conversion coating on steel, the economical standard for indoor and light outdoor parts.

Condition where part of a network stays energised by local generation after being cut off from the main grid.

The international standard setting the competence requirements for testing and calibration laboratories.

Diffuse blue reflectance factor at 457 nm, measured with d/0 geometry and UV content matched to illuminant C.

Three-number code for how many particles above 4, 6 and 14 microns are in a millilitre of fluid.

Larger elastomer-sealed flange family, clamped with claws or bolted, used for pump and chamber ports.

The 60-degree metric screw thread, written as M plus diameter and pitch in millimeters, such as M10 x 1.5.

ISO viscosity grade, the number on an industrial oil that names its kinematic viscosity in cSt at 40 C.

A full-depth separation between a slab and a fixed element, so each can move without cracking the other.

Earthing arrangement in which the source is isolated from earth or earthed only through a high impedance.