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Paladon Systems Valve Automation Glossary

Wall Thickness

The thickness of the wall of a pressure vessel or of a pipe.

Water Hammer

The physical effect often accompanied by loud banging produced by pressure waves generated within the piping by rapid change of velocity in a liquid system.

WE (Weld End)

The end connection of a valve which is to be installed by welding into the line. To prepare the end bevel, it is necessary to know the wall thickness and specified minimum yield strength of the connecting pipe. See End Bevel.


Damage to a solid surface generally involving progressive loss of material due to relative motion between that surface and a contacting substance or substances.

Wear Test

Verification of a component’s resistance under specific wear conditions.


Of a device that is protected against intrusion of water, sand, dust or other atmospheric contamination.

Wedge Gate Valve

A gate whose seating surfaces are inclined to the direction of closing thrust so that mechanical force on the stem produces tight contact with the inclined seat rings. Manufactured to API 600.

Weld Neck Flange

A flanged piping element with a weld-neck used in pipeline construction to provide a companion flange for installation of flanged valves. Also used to convert weld end valves to flanged valves or vice versa.

Weld Reducers

A reducing fitting used on weld end piping components to adapt from a large sized pipe to a smaller diameter pipe or vice versa.

WO (Wrench Operated)

The operation of a valve by means of a handle or lever. Used on smaller size and lower pressure class valves.

WOG (Water Oil Gas)

Used in connection with a pressure rating. 100 WOG indicates that the rated pressure is 100 psi in water, oil or gas service at normal ambient temperatures.

Worm Gear

Gear used to transmit motion or power between right angle shafts when a high-ratio reduction is necessary. The worm is the small gear which drives the larger ring gear. Worm threads resemble screw threads and are available in various leads and pitches. See BGO (Bevel Gear Operated).

WP (Working Pressure)

The pressure at which a valve is designed to operate. Same as operating pressure rating.

Wrought Products

Products shaped by means of forging or hot isostatic pressing.

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