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
Cage
A hollow cylindrical trim element that is a guide to align the movement of a valve plug with a seat ring and also retains the seat ring in the valve body. Often the walls of the cage contain opening which determines the flow characteristics of the control valve.
Capacity
Rate of flow through a valve under stated conditions.
Capscrew
A fastener having a head and whose shank is normally threaded throughout its entire length. Not used with a nut, but rather engagement is made with a female thread in the piece to be joined.
Casting
A part made by pouring molten metal into a mold without any further forging or rolling.
Cavitation
The formation and subsequent collapse within a liquid of cavities or bubbles that contain vapor or gas or both. Cavitation originates from a local decrease in hydrostatic pressure in the liquid, produced by motion of the liquid or of a solid boundary. The term cavitation should not be used to denote the damage or erosion of a solid surface that can be caused by it. This effect of cavitation is termed cavitation damage or cavitation erosion.
CBV (Control Ball Valve)
An automatic throttling valve controlling flow or pressure in a pipeline; comprising a package involving a ball valve, an actuator, a positioner and controlling instruments.
CE Marking
The CE marking is a mandatory European marking for certain product groups placed on the European Economic Area (EEA) to indicate conformity with the essential health and safety requirements set out in European Directives. To permit the use of a CE mark on a product, proof that the item meets the relevant requirements must be documented.
Certifying Authority (CA)
An independent body appointed by the purchaser to carry out a survey of the equipment and/or materials that they are buying. It is the responsibility of the supplier to provide the C.A. with information, documents, access to works and personnel to enable the survey to be carried out.
Chainwheel
A chain operated wheel attached to a manual actuator with a closed loop of chain to enable the operation of an overhead valve.
Chainwheel Operated Valve
An overhead valve operated by a chain drive wheel instead of a handwheel.
Characterized Ball or Gate
A ball or gate, the shape of whose port has been altered to provide a specific throttling capability. One of the most common is the V-Port ball design.
Charpy Impact Test
A mechanical dynamic test that provides a measure of the energy required to break a material under impact loading. The test consists essentially of a hammer with a given amount of energy striking a notched specimen of fixed dimensions. The measured test values may be the energy absorbed, the percentage shear fracture, the lateral expansion opposite the notch or a combination thereof. It provides a relative measure of the toughness of steel or its resistance to shock or impact loads. Often required for low temperature applications where testing is done at the expected minimum service temperature. Test procedure is defined in ASTM A370.
Check Valve
A unidirectional valve which is opened by the fluid flow in one direction and which closes automatically when the flow stops or reverses direction.
Check Valve Clapper Disc
The hinged closure element of a swing check valve.
Chevron Packing
A type of packing used in packing boxes consisting of a nest of “V” cross-section rings. Also termed Vee-pack.
Choke Valve
A choke valve is a valve that lifts up and down a solid cylinder (called a “plug” or “stem”) which is placed around or inside another cylinder which has holes or slots. The design of a choke valve means fluids flowing through the cage are coming from all sides and that the streams of flow (through the holes or slots) collide with each other at the centre of the cage cylinder, thereby dissipating the energy of the fluid through “flow impingement”. The main advantage of choke valves is that they can be designed to be totally linear in their flow rate.
Cladding
A method of coating metals with another metal and where the coating becomes an integral part of the base material. This is usually done by welding. Also termed Weld Overlay.
Clamp Connector
Developed as the high pressure, low weight, leak-free alternative to the ANSI flange. The clamp connector does not rely on complex bolting to maintain seal integrity, but offers the strength of a welded joint. This design is the preferred solution where space, weight and joint integrity are critical. Typically of a proprietary design, e.g. Destec, Grayloc (Oceaneering International) and Techlok (Vector International).
Clevis Pin
A “U” shaped connecting yoke at the end of a stem, between the ends of which a gate or other part may be pinned or bolted. It allows rotation of the connected parts about the axis of the pin.
Closure
The ends of a ball valve bolted to the body which usually contain the seat rings. Often referred to as part of the body.
Closure Element
The moving part of a valve, positioned in the flow stream which controls flow through the valve. Ball, gate, plug, clapper, disc, etc. are specific names for closure elements. Also termed Obturator.
Coil
Insulated wire is wound onto a spool through which electric current is passed to create a magnetic field.
Cold Flow
Increasing deformation of a material under a constant load at temperatures within the working range. Also termed Creep.
Compact Flange
Compact flange was developed by Steel Products Offshore A/S, using extensive testing and finite element analysis. This design is a smaller and lighter alternative to conventional ANSI flanges. Has been adopted in Norsok Standard L-005 “Compact flanged connections”.
Compression (Compressive) Modulus
The ratio of the compression stress to the resulting compression strain below the proportional limit (expressed as a percentage of the original specimen thickness). Defined in ISO 604 and ASTM D695.
Compression Molding
Thermoset molding technique in which the uncured rubber compound is put in a heated, open mold cavity and the mold is closed under pressure (often in a hydraulic press). The material flows to completely fill the cavity. Pressure is maintained until curing is complete.
Compression Set
The permanent deformation remaining after release of a compressive stress on an elastomeric specimen. Compression set is expressed as the percentage of the original deflection. Referred to in ISO 815 and ASTM D395.
Compressor
A device which converts mechanical power or force to pneumatic power or force.
Concentric
Having the same centres.
Contaminant
A particle or material which is foreign to the fluid media.
Control Valve
A valve that controls a process variable, such as pressure, flow or temperature by modulating its opening in response to a signal from a controller.
Controller
A device that measures a controlled variable, compares it with a predetermined setting and signals the actuator to re-adjust the opening of the valve in order to re-establish the original control setting.
Corrosion
The change in the properties of a metal by chemical or electrochemical reaction with its environment.
Corrosion Resistant Alloy
Non-ferrous-based alloy in which any one of the sum of the specific amount of the elements titanium, nickel, cobalt, chromium, and molybdenum exceeds 50% in weight.
Coulisse
A type of gate valve using runners or slides as a guiding mechanism operating in high temperature applications i.e. +300°C.
Cracking
A chemical process whereby complex organic molecules such as heavy hydrocarbons are broken down into simpler molecules by the breaking of carbon-carbon bonds.
Creep
Increasing deformation of a material under a constant load below the yield strength. Also termed Cold Flow.
Crevice Corrosion
A form of accelerated localized corrosion occurring at locations where easy access to the bulk environment is prevented, such as mating surfaces of metal assemblies.
Cryogenic Temperature
Any temperature below about -196°C.
Cryogenic Valve
A valve capable of functioning at cryogenic temperatures below i.e. -196 °C commonly used in LNG plants.
CV
The volumetric flow rate of water, in US gallons per minute at 15.6 °C (60 °F) passing through a valve and resulting in a pressure drop of 1 psi.
Cycle
A single complete operation or process returning to the starting point. A valve stroked from full open to full closed and back to full open has undergone one cycle.
Cycle Test
A procedure whereby a product is put through an interval of time during which a phenomena is completed. This can be a set number of events or it can be a continuous operation until something in the product fails.
Cycle Time
The time to actuate a valve from open to close. Time normally specified by the required process conditions and can be adjustable.
Cylinder
The motive force for a pneumatic or hydraulic actuator is generated by a plunger or piston being pressurized inside a cylindrical housing.
Cylinder Operator
A power-piston valve operator which uses either hydraulic or pneumatic pressure. A sealed piston converts applied pressure into a linear piston rod (stem) motion.