IBV
Acronym for an internal bottom ball valve. This is an angle style valve whose body and inlet opening extend into the tank. See "Bottom Outlet Valve"; "Ball Valve"; "Angle Valve."

INDUSTRIAL CARRIER
A short line railroad owned or controlled by one or more of the principle industries served by it. May be organized as a common carrier or merely a private carrier or plant facility.

INJURIOUS DEFECT
Any discontinuity (crack, lamination, pit, hard spot, etc.) that results in a change in the material's physical properties, so as not to meet specification requirements.

INNAGE
A measurement of the number of gallons of commodity contained in a tank. Usually determined indirectly by measuring to the liquid level in the tank and then consulting a precalculated table.

INSULATED
Refers to a tank, fitting, housing, draft sill, or other car appurtenance whose outside surfaces are covered with a thermal insulating material.

INSULATION (CAR CONSTRUCTION)
In general, any material that serves to decrease the flow of heat through a structural wall from one space to another. Common insulating materials in rail car applications include polyurethane foam, ceramic fiber, and fiberglass. Dead air space between wall panels also serves as effective insulation.

INTERCHANGE
The transfer of cars from one road to another at a common junction point.

INTERCHANGE RULES
A set of regulations adopted by the Association of American Railroads governing the care and handling of freight cars operating in interchange service. The Interchange Rules are contained in two publications known as the Field Manual and the Office Manual, and are revised and reissued annually to meet changing conditions.

INTERIOR BLAST
See "Exterior Blast" but used on the interior of the car.

INTERIOR COATING
A coating sprayed onto the interior surfaces of a tank; sometimes requiring heat curing. The purpose is to either protect the tank from corrosion or protect the commodity from contamination, or both.

INTERIOR COILS
See "Heater Pipes."

INTERIOR PREP
The blasting and/or grinding of the interior surfaces of a tank usually in anticipation of lining or coating application.

INTERLINE FREIGHT
Freight moving from point of origin to destination over the lines of two or more carriers.

INTER-MODAL
A term used to describe freight containers that are designed to be easily transferred from one basic mode of transport to another. See "Mode."

INTERNAL BALL VALVE
See "IBV."

INTRA-PLANT SWITCHING
The moving of cars from one place to another within a plant.

IXC
Acronym for an insulated and exterior coiled tank car.