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
Fabricated Valve
A valve in which the body is neither cast nor forged but rather is formed from plate or pipe welded together.
Face-to-Face
The overall dimension from the inlet face to the outlet face of the valve (one end to the other). This dimension is governed by ASME B16.10 and for pipeline valves, API 6D / ISO 14313, to ensure that such valves are mutually interchangeable regardless of the manufacturer.
Facing
The finishing of the contact surface of flanged fittings.
Fail-Safe Valve
When there is a failure in the pipeline system, the actuated valve is designed to automatically either open or close the valve.
Fatigue Assessment
Fatigue resistance verification of a component subjected to a number of design/operating cycles.
Fatigue
The phenomenon leading to fracture under repeated or fluctuating stresses having a maximum value less than the tensile strength of the material.
FEA (Finite Element Analysis)
A numerical method of analysing complex shapes by organizing the volume into a series of smaller elements which can be more accurately analysed to determine whether or not components are suitable for their intended purpose.
Feedback
The process of transferring data from the output of a system to the input typically for valve position monitoring.
Female Thread
An internal screw thread designed to mate with a component having male (external) threads of the same size and type.
Field Serviceable
Any equipment is field serviceable when normal repair or replacement of operating parts can be accomplished in the field without returning to the manufacturer.
Fieldbus
A digital, serial, two-way communications system that interconnects measurement and control devices such as sensors, actuators and controllers. Additional intelligence can be embedded in field devices which can allow calibration and diagnostics and decentralised control.
Filter
A device incorporated into a system to remove contaminants from the fluid.
Firepoint
The temperature at which a fuel will continue to burn after ignition.
Firesafe
This is a term used to describe the fire resistance ability of a valve when exposed to fire. In order to qualify for this certification, a valve is required to be exposed to fire for a 30-minute period. Once acceptable leakage (through the test valve and also external leakage) has been confirmed, the valve is considered to be firesafe. Some common fire testing specifications include ISO 10497, BS 6755 Part 2, API Spec 6FA, API Spec 6FC, API Spec 6FD and API 607 (3rd Edition).
Fitting
Any device used for connecting elements in fluid lines e.g. elbows, tees, nipples, unions, flanges, etc.
Flange
A cast or formed pipe fitting consisting of a projecting radial collar with bolt holes to provide means of attachment to piping components having a similar fitting. The end piece of flanged end valves.
Flash (Molding Flash)
Excess of materials attached to a molded product which usually must be removed.
Flashing
The phenomenon by which a fluid vaporizes due to sudden pressure drop across a valve. Beside physical damages, the occurrence of flashing within a control valve results in a decreased ability of the valve to convert pressure drop across it into mass flow rate.
Flashpoint
The lowest temperature at which a flammable liquid can form an ignitable mixture in air.
Flexible Tube Valve
A special valve using a flexible sleeve or tube which acts as the closure element. Pressure applied to the jacket space surrounding the outside of the tube controls the opening and closing of the valve.
Floating Ball Valve
A ball valve having a non-trunnion-mounted ball. The ball is free to float between the seat rings and thus causes higher torques.
Flow
A fluid in motion in a conducting line.
Flow Coefficient Kv
The volumetric flow rate of water, in cubic meters per hour, at a temperature between 5°C and 40°C, passing through a valve and resulting in a pressure loss of 1 bar. When expressed in Imperial units it is known as Cv.
Flow Control Valve
Similar to a Speed Control Valve in the fact that a Flow Control Valve restricts fluid flow, but unlike a Speed Control Valve, it only restricts fluid flow in one direction.
Flow Rate
The volume or weight of a fluid passing through a pipeline or conductor per unit of time.
Flowmeter
An instrument used to measure flow rate or total flow or both.
Fluid
Any non-solid substance that can be made to flow. Both liquids and gases are fluids.
Fluorocarbon
Carbon backbone, organic compound having fluorine atoms in its chemical structure. Presence of the fluorine provides increased chemical and high temperature resistance.
Flushing
A procedure for hydraulic systems of cleaning the fluid to a pre-determined standard. NAS (National Aeronautical Standard) 1638 is typically used, with NAS 6 being the most common requirement.
Force
The intensity of an influence tending to produce motion, distortion or change of shape. The product of pressure (bar) and the area over which it acts. Usually expressed in Newton (SI units) or pounds (non-SI units).
Forging
A part that is formed by heating and hammering to a specific shape.
Frame
The centre enclosure of an actuator housing the Scotch-Yoke mechanism.
Frangible Bulb
A liquid filled glass device for detecting high temperature. At a predetermined temperature the bulb fractures causing the control valve to change state and signal the actuator to close the valve.
Fretting
Small amplitude oscillatory notion usually tangential between two solid surfaces in contact.
Fretting Corrosion
A form of fretting wear in which corrosion plays a significant role.
Fretting Wear
Wear arising as a result of fretting.
Friction
The resistance to motion between two contacting surfaces or substances. Friction is also developed between a flowing fluid and the inner wall of the conducting pipe-resulting in a drop in pressure.
Fugitive Emission Test
A fugitive emission is defined as a leak from a fluid (e.g. hydrocarbons, chemical or mixture of chemicals). The fugitive emission (FE) test is carried out to evaluate the ability to suppress and/or the performance level of on/off valves and control valves with regards to FE. The specification for FE testing describes the type of detection method and test medium to be used and specify the acceptance and rejection criteria.
Full Bore
Describes a valve whose bore (port) is nominally equal to the bore of the connecting pipe.
Full Penetration Weld
Describes the type of weld wherein the weld metal extends across the entire wall thickness of the joint.
Fully Welded Ball Valve
Refers to a ball valve whereby the body and closure joints are fully welded to complete the valve assembly. This type of valve construction cannot be disassembled nor repaired at site.
Fusible Link
3 port device with one port blocked with a metal with a low melting point. In the event of a fire, the metal will melt resulting in the line being vented to atmosphere and becomming depressurised.
Fusion Hardfacing
A process by which weld materials, with superior properties than the substrate are applied to the substrate. Often two layers total 3 – 6 mm thick are applied to reduce the surface hardness dilution of the relatively low-cost steel substrates in the expansive cobaltbased alloys. Hardfacing processes are very useful for improving wear and corrosion resistance to selected areas of mechanical equipment such as cutting edges of earth-moving machinery or sealing areas of valves. Common hardfacing techniques include arc torch (GMAW, GTAW, SMAW, SAW) and other processes (ESW).