GAS FREEA term used to describe a space that has
been tested and found safe for hot work (welding
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
GAUGE (SIGHT) GLASSA device that indicates the
liquid level in a tank.
GEARED-TURBINE DRIVEA turbine that drives a
pump, generator, or other machinery through
GROUNDED PLUGA three-pronged electrical plug
used to ground portable tools to the ships structureIt
is a safety device that must always be checked
before portable electrical tools are used.
HALIDE LEAK DETECTORA device used to
locate leaks in refrigeration systems.
HANDHOLEAn opening large enough for the hand
and arm to enter for making slight repairs and for
HARDENINGThe heating and rapid cooling
(quenching) of metal to induce hardness.
HEADERA large pipe to which smaller pipes are
connected so that the liquid may pass freely from
one pipe to the other(s).
HEAT EXCHANGERAny device that allows the
transfer of heat from one fluid (liquid or gas) to
HERTZA unit of frequency that equals 1 cycle per
HYDROGENA highly explosive, light, invisible,
HYDROMETERAn instrument used to determine the
specific gravity of liquids.
HYDROSTATIC TESTA pressure test that uses
water to detect leaks in closed systems.
IGNITION, COMPRESSIONThe heat generated by
compression in an internal combustion engine that
ignites the fuel (as in a diesel engine).
IGNITION SPARKThe electric spark that ignites the
mixture of air and fuel in an internal combustion
engine (as in a gasoline engine).
IMPELLERAn 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 TURBINEA turbine in which the major
part of the driving force is received from the impulse
of incoming steam. See REACTION TURBINE.
INDIRECT DRIVEA drive mechanism coupled to
the driven member by gears or belts.
INJECTORA 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
INSULATIONA material used to retard heat transfer.
INTERCOOLERAn intermediate heat transfer unit
between two successive stages, as in an air
JACKBOXA receptacle, usually secured to a
bulkhead, into which telephone plugs or jacks are
JOB ORDERAn order issued by a repair activity to
its own subdivision to perform a repair job in
response to a work request.
JP5A 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 RIGAny temporary or makeshift device.
LABYRINTH PACKINGRows of metallic strips or
fins that minimize steam leakage along the shaft of
LAGGINGA protective and confining cover placed
over insulating material.
LIGHT OFFTo start a tire, as in light off a boiler.
LINE UPTo align a system for operation.
LOGBOOKAny chronological record of events, such
as an engineering watch log.
LOG, ENGINEERINGA legal record of important
events and data concerning the machinery of a ship.
LOGROOMThe engineers office aboard ship.
LUBE OIL PURIFIER-A unit that removes waste and
sediment from lubricating oil by centrifugal force.