Glossary


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

ABRASION

Progressive wearing away of material.

ABRASION RESISTANCE

The ability of a material to resist mechanical wear.

ACCELERATED SERVICE TEST

Any set of test conditions designed to reproduce in a short time the deteriorating effect obtained under normal service conditions.

ACTIVE INHIBITOR

A type of galvanic corrosion inhibitor added to packing. It acts as a sacrificial anode, corroding in preference to the surrounding metal. Zinc dust is added to the surface of some packing materials as an active inhibitor. See also "Galvanic Corrosion". Compare with "Passive Inhibitor".

ACTUATE

To cause movement of a valve stem either by raising, lowering, or turning it.

ACTUATOR

A device, attached to a valve, which moves the stem, usually by means of a motor or pneumatics. A valve fitted with an actuator is usually referred to as a control valve.

ADHESION

The clinging, binding or sticking of two material surfaces to one another, such as rubber to rubber, rubber to metal, or rubber to cloth. It also refers to the bond strength between two surfaces.

AGING

Undergo changes to physical properties with lapse of time.

AMBIENT TEMPERATURE

The temperature of the surrounding environment.

ANCHOR

Terminal point or fixed point from which directional movement occurs.

ANGLES

L-Shaped steel member used either as a duct flange or as the fastening connection of an expansion joint. Angles are also used for bolting the joint to the mating flange surfaces of the duct work or adjacent equipment.

ANGULAR MOVEMENT

Movement which occurs when one flange of the expansion joint is moved to an out of parallel position with the other flange. Angular movement is measured in degrees.

ANSI

Abbreviation for "American National Standard Institute".

ANTI-EXTRUSION RING

A ring of packing used at one or both ends of a packing set to prevent extrusion of the packing into clearances. Also called a "Bull Ring." See also "End Ring" and "Junk Ring."

AOV

Abbreviation for "Air Operated Valve", a pneumatically actuated valve.

API

Abbreviation for American Petroleum Institute.

AQUEOUS SOLUTIONS

Any fluid solution containing water. See further discussion under "pH."

ARAMID

A family of polymers used in a fibrous form as packing materials. Kevlar® is a DuPont trade name for an aramid fiber known for its excellent abrasion resistance, high tensile strength, and its characteristic deep yellow color. Nomex® is the DuPont trade name for another type of aramid fiber.

ASME

Abbreviation for American Society of Mechanical Engineers.

ASSEMBLED SPLICE

A splice that is constructed of multi layers of materials and connected by use of elastomeric cements, adhesives, etc.

ASSEMBLED SPRING INSIDE DIAMETER

The inner diameter of the garter spring, with the ends securely joined.

ASTM

Abbreviation for American Society for Testing and Materials.

AUTOCLAVE

In the rubber sheet manufacturing industry, the device used to vulcanize (cure) elastomers. Typically the autoclave is drum-shaped, open on one end, and is steam-heated.

AXIAL

In the direction of a shaft or stem axis.

AXIAL CLEARANCE

The gap between the toe face to the head section and the inside surface of the inner case.

AXIAL COMPRESSION

The dimensional shortening of an expansion joint parallel to its logitudinal axis. Such movement being measured in inches or millimeters and usually caused by thermal expansion of the piping/ducting system.

AXIAL EXTENSION

The dimensional lengthening of an expansion joint parallel to its logitudinal axis. Such movement being measured in inches or millimeters.

AXIAL SURFACE ROUGHNESS

Surface roughness of a shaft measured in a direction parallel with the centerline axis.