GAS FREE–A term used to describe a space that has
been tested and found safe for hot work (welding
and cutting).
GAS GENERATION (GG)–The high-pressure section
of the main propulsion gas turbineIt includes the
compressor, combustor, high-pressure turbine,
front frame, compressor rear frame, turbine mid
frame, transfer gearbox, and the controls and
accessories.
GAUGE (SIGHT) GLASS–A device that indicates the
liquid level in a tank.
GEARED-TURBINE DRIVE–A turbine that drives a
pump, generator, or other machinery through
reduction gears.
GROUNDED PLUG–A three-pronged electrical plug
used to ground portable tools to the ship’s structureIt
is a safety device that must always be checked
before portable electrical tools are used.
HALIDE LEAK DETECTOR–A device used to
locate leaks in refrigeration systems.
HANDHOLE–An opening large enough for the hand
and arm to enter for making slight repairs and for
inspection purposes.
HARDENING–The heating and rapid cooling
(quenching) of metal to induce hardness.
HEADER–A large pipe to which smaller pipes are
connected so that the liquid may pass freely from
one pipe to the other(s).
HEAT EXCHANGER–Any device that allows the
transfer of heat from one fluid (liquid or gas) to
another.
HERTZ–A unit of frequency that equals 1 cycle per
second.
HYDROGEN–A highly explosive, light, invisible,
nonpoisonous gas.
HYDROMETER–An instrument used to determine the
specific gravity of liquids.
HYDROSTATIC TEST–A pressure test that uses
water to detect leaks in closed systems.
IGNITION, COMPRESSION–The heat generated by
compression in an internal combustion engine that
ignites the fuel (as in a diesel engine).
IGNITION SPARK–The electric spark that ignites the
mixture of air and fuel in an internal combustion
engine (as in a gasoline engine).
IMPELLER–An encased, rotating element provided
with vanes that draws in fluid at the center and
expels it at a high velocity at the outer edge.
IMPULSE TURBINE–A turbine in which the major
part of the driving force is received from the impulse
of incoming steam. See REACTION TURBINE.
INDIRECT DRIVE–A drive mechanism coupled to
the driven member by gears or belts.
INERT–Inactive.
INJECTOR–A device that forces a fluid into an area.
Injectors are used in the diesel engine to deliver fuel
into the cylinders and in boilers to force water into
the boilers.
INSULATION–A material used to retard heat transfer.
INTERCOOLER–An intermediate heat transfer unit
between two successive stages, as in an air
compressor.
JACKBOX–A receptacle, usually secured to a
bulkhead, into which telephone plugs or jacks are
inserted.
JOB ORDER––An order issued by a repair activity to
its own subdivision to perform a repair job in
response to a work request.
JP5–A fuel oil similar to DFM.
JUMPER-Any connecting pipe, hose, or wire normally
used in emergencies aboard ship to bypass damaged
sections of a pipe, a hose, or a wireSee BYPASS.
JURY RIG–Any temporary or makeshift device.
LABYRINTH PACKING–Rows of metallic strips or
fins that minimize steam leakage along the shaft of
a turbine.
LAGGING–A protective and confining cover placed
over insulating material.
LIGHT OFF–To start a tire, as in light off a boiler.
LINE UP–To align a system for operation.
LOGBOOK–Any chronological record of events, such
as an engineering watch log.
LOG, ENGINEERING–A legal record of important
events and data concerning the machinery of a ship.
LOGROOM–The engineer’s office aboard ship.
LUBE OIL PURIFIER-A unit that removes waste and
sediment from lubricating oil by centrifugal force.
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