Midterm Flashcards
the difference between the initial lift-off pressure and the pressure of the fully open position for a relief valve
Accumulation
a device that controls the position of the flow-control element on a control valve by automatically adjusting the position of the valve stem.
Actuator
a valve that operates by admitting fluid flow to the gate or plug and redirecting it 90° out the discharge port
Angle Valve
lubricant used on exposed valve stem threads
Antiseize compound
also known as self-actuating, these valves perform their specific function without external assistance
automatic valve
A valve named for the ball-shaped, movable element in the center of the valve
ball valve
any valve that is intended to block flow; also called an isolation valve. The term generally refers to gate valves
block valve
a bell-shaped dome mounted on the body of a valve, which provides a housing for the flow control element when lifted out of the flow
bonnet
manufacturer information on the body of a valve
bridgewall markings
an adapter threaded to permit joining of pipes with different diameters
bushing
valve characterized by their disc-shaped flow-control element, which pivots from its center
butterfly valve
mechanical valves that prevent reverse flow in piping
check valves
dome shaped element attached to the valve stem which
presses on the flexible diaphragm to restrict flow
compressor (diaphragm valve)
a collection of instruments that work together to automatically control a process; usually consists of a sensing device, a transmitter, a controller, a transducer, and an automatic valve
control loop
automated valves used to regulate and throttle flow; typically provide the final control element of a control loop
control valves
the equipment concerned with controlling the operation of an electrical device
controller
something flexible that serves as a barrier
diaphragm
a valve that uses a flexible membrane to regulate flow
diaphragm valve
a device made of metal or ceramic that fits snugly in the seat of a valve to control flow
disc
the part of a valve that regulates flow; that is, the gate or the disc
flow-control element
liquid and gas forms of matter (not solids).
fluid
the flow-control element of a gate valve.
gate
a valve with a movable metal gate in the path of a process flow
gate valve
a device that places a disc in the path of a process flow
globe valve
attachment to the valve stem used to control the position of the flow-control element of a valve
handwheel
a valve that completely obstructs the path of a fluid and isolates a part of a system.
isolation valve
valve with multiple inlets and/or outlets in specialized piping systems to divert flow direction, allowing fluid sources to be switched.
multiport valve
a type of globe valve that has a needle-shaped element that fits snugly into the seat
needle valve
a type of valve mechanism that has a collar that keeps the stem from moving up and down. You cannot tell if this type of valve is open or closed by looking at it
nonrising stem
a specially designed material used to stop fluid from entering or escaping; packed around the shaft (stem) of a valve, or shaft of a pump
packing
a mechanical device that contains and compresses packing
packing gland
device that uses an airtight cylinder and piston to move or position the stem; it is commonly used with automated gate valves or slide valves
piston actuator
a valve that has a plug-shaped element; used for on/off service
plug valve
valve set to automatically relieve pressure in a closed system at a predetermined set point for liquids
relief valve
a type of valve mechanism in which the stem of the valve rises along with the gate, disk, or globe when opened. You can tell if this type of valve is open or closed by looking at it
rising stem
valve set to automatically relieve pressure in a closed system at a predetermined set point for gases
safety valve
a device that keeps track of the measured condition (e.g., temperature, pressure) and its fluctuations so that when sufficient variation occurs it will originate the signal to change the operation of the system
sensing device
the section of a valve that contains packing
stuffing box
a valve with three ports (one inlet and two outlets) used to divert flow direction
three-way valve
reducing or regulating flow below the maximum output of a valve
throttling
a device that converts variations in a physical quantity, such as pressure or temperature, into an electrical signal, or vice versa
transducer
an electronic device used to generate and send electromagnetic waves carrying messages or signals
transmitter
the flow-control element and seats in a valve
trim
a fluid flow in which the velocity at a given point varies erratically in magnitude and direction. In valves, can cause metal erosion, seat damage, and damage to the flow controlling element
turbulent flow
a device used to stop, start, restrict (throttle), or direct the flow of fluids
valve
the outer casing of most or all of the valve that contains the internal parts or trim
valve body
the total amount of fluid a valve will pass with a given pressure difference when it is fully open
valve capacity
the fixed surface on which a valve controlling element rests or against which it presses
valve seat
a long, slender metal shaft attached to the handwheel and flow-control element of a valve
valve stem
device used to direct air against paddles or vanes, are frequently used on quarter-turn valves
vane actuator
become bent or twisted out of shape. In valves, caused by temperature changes, pipe expansion, or closing a valve too quickly. Leads to valve sticking or seizing
warp
a device used to connect (bolt) piping to industrial equipment
flange
Enhances arc starts and provides a softer arc throughout all ranges, with less puddle turbulence and less spatter
Active Arc Stabilizer
Automatically increases the output amperage at the start of a stick weld, should the start require it. Helps eliminate sticking of the electrode at arc start
Adaptive Hot Start
A cutting process by which metals are melted by the heat of an arc using a carbon electrode. Molten metal is forced away from the cut by a blast of forced air
Air Carbon Arc Cutting (CAC-A)
An electrical current that reverses its direction at regular intervals, such as 60 cycles alternating current (AC), or 60 hertz
Alternating Current (AC)
The measurement of the amount of electricity flowing past a given point in a conductor per second (i.e., current)
Amperage (amps)
The physical gap between the end of the electrode and the base metal. The physical gap causes heat due to resistance of current flow and arc rays
Arc
Gives a power source variable additional amperage during low voltage (short arc length) conditions while welding. Helps avoid “sticking” stick electrodes when a short arc length is used
Arc Control (Dig)
A group of thermal cutting processes that severs or removes metal by melting with the heat of an arc between an electrode and the work piece
Arc Cutting
A group of welding processes which produces coalescence of metals by heating them with an arc, with or without the application of pressure and with or without the use of filler metal.
Arc Welding
Automatically enhances Stick welding, especially on pipe, by focusing the arc and preventing the electrode from going out
Arc-Drive
Allows a TIG (Tungsten Inert Gas) arc to crater-out, allowing time for the addition of filler, without the loss of shielding gas. Eliminates the need for a remote control at arc end
Auto-Crater
The control of a process with equipment that requires little or no observation of the welding and no manual adjustment of the equipment controls
Automatic
A material (base metal, weld metal, or granular material) placed at the root of a weld joint for the purpose of supporting molten weld metal
Backing
A welding aid used to prevent melting through of a joint when performing a complete-joint penetration groove weld
Backing Bar
A shielding gas used on the underside of a weld bead to protect it from atmospheric contamination
Backing Gas
A weld bead applied to the root of a single groove joint to assure complete root penetration
Backing Weld
A joint between two members lying in the same plane
Butt Joint
A weld where two pieces of metal are to be joined are in the same plane
Butt Weld
Welding machine with limited maximum short circuit current. They have a negative volt-amp curve and are often referred to as “droopers.”
Constant Current (CC) Welding Machine
Welding machine that maintains a relatively stable, consistent voltage regardless of the amperage output. It results in a relatively flat volt-amp curve
Constant Voltage (CV), Constant Potential (CP) Welding Machine
Feeder operates from 24 or 115 VAC supplied by the welding power source
Constant-Speed Wire Feeder
The amount of electricity flowing past a point in a conductor every second
Current
The physical destruction of the completed weld in order to evaluate its
characteristics
Destructive testing
Current that flows in one direction and does not reverse its direction of flow
Direct Current (DC)
The direction of current flow through a welding circuit when the electrode lead is connected to the negative terminal and the work lead is connected to the positive terminal of a DC welding machine. Also called direct current, straight polarity (DCSP).
Direct Current Electrode Negative (DCEN)
The direction of current flow through a welding circuit when the electrode lead is connected to a positive terminal and the work lead is connected to a negative terminal to a DC welding machine. Also called direct current, reverse polarity (DCRP)
Direct Current Electrode Positive (DCEP)
The number of minutes out of a 10-minute time period an arc welding machine can be operated at maximum rated output
Duty Cycle
A type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point
Electric Arc Welding
An arc welding process, which combines features of gas and shielded welding with those of electro-slag welding
Electro-Gas Welding
A welding process that is used for welding heavy structure components
Electro-Slag Welding
The process of joining two pieces of metal together that are perpendicular or at
an angle
Fillet welding
Automated electronically controlled welding system for simple, straight or circular welds
Fixed Automation
Automated, robotically controlled welding system for complex shapes and applications where welding paths require torch-angle manipulation
Flexible Automation
An arc welding process that produces coalescence of metals by means of tubular electrode. Shielding gas may or may not be used
Flux-Cored Arc Welding (FCAW)
A solid-state welding process, which produces coalescence of material by the heat obtained from a mechanically induced rotating motion between tightly butted surfaces. The work parts are held together under pressure
Friction Stir Welding
A solid welding process which produces coalescence of material by the heat obtained from a mechanically induced sliding motion between rubbing surfaces. The work parts are held together under pressure
Friction Welding
A process that uses gases and oxygen to weld and cut metals, respectively
Gas Cutting
An arc welding process where the arc is between a continuous filler metal electrode and the weld pool. Shielding from an externally supplied gas source is required
Gas Metal Arc Welding (GMAW)
An arc welding process where the arc is between a tungsten electrode (non-consumable) and the weld pool. The process is used with an externally supplied shielding gas
Gas Tungsten Arc Welding (GTAW)
Welding with the heat from an oxy-fuel flame, with or without the addition of filler metal or pressure
Gas Welding
Named for “globs” of weld metal transferring across the arc in a gravity feed. Droplets across the arc are usually larger than the electrode diameter. It does not produce a very smooth weld bead appearance, and some spatter can occur. Usually limited to the flat and horizontal welding positions, and not used on thin metals
Globular Transfer
A safety connection from a welding machine frame to the earth
Ground Connection
A unit of frequency that measures cycles per second
Hertz
Covers the entire frequency spectrum above 50,000 Hz. Used in TIG welding for arc ignition and stabilization
High Frequency
Used on some stick (SMAW) machines to make it easier to start difficult-to-start electrodes. Used for arc starting only
Hot Start
A combination of laser and arc welding which produces deep penetration welds with good tolerance to poor joint fit-up
Hybrid laser-arc welding
Power source that increases the frequency of the incoming primary power, thus providing for a smaller size machine and improved electrical characteristics for welding, such as faster response time and more control for pulse welding
Inverter
The total volts times amps divided by 1,000, demanded by a welding power source from the primary power furnished by the utility company
KVA (Kilovolt-amperes)
A measure of power, calculated as volts times amps divided by 1,000
KW (Kilowatts)
A joint between two overlapping members in parallel planes
Lap Joint
A process that severs material with the heat from a concentrated coherent beam impinging upon the work-piece
Laser Beam Cutting
A process that fuses material with the heat from a concentrated coherent beam impinging upon the members to be joined
Laser Beam Welding
A technology that is used for industrial manufacturing applications and uses a laser to cut materials
Laser Cutting
A welding process that offers low heat input and minimum distortion of welded plates and stiffeners
Laser Welding
This feature allows TIG arc starting without high frequency. Starts the arc at any amperage without contaminating the weld with tungsten
Lift-Arc
A device that provides a concentrated coherent light beam
Light Amplification by Stimulated Emission of Radiation (Laser)
A subtype of GMAW that uses an inert gas or gas mixture for shielding. Typically used on aluminum and other non-ferrous metals
MIG Welding
A gas that has been heated to at least partially ionized condition, enabling it to conduct an electric current
Plasma
An arc welding process that uses a constricted arc between a non-consumable electrode and the weld pool (transferred arc) or between the electrode and the constricting nozzle (non-transferred arc). Shielding is obtained from the ionized gas issuing from the torch
Plasma Arc Welding (PAW)
An arc cutting process using a constricted arc to remove the molten metal with a high-velocity jet of ionized gas from the constricting orifice
Plasma-Arc Cutting (PAC)
How well an electrical machine uses the incoming electrical power
Power Efficiency
Normally used on single-phase, constant current power sources to reduce the amount of primary amperage while welding
Power Factor Correction
The input line voltage and amperage available to the welding machine from the shop’s main power line, single-phase or three-phase AC power expressed in watts or kilowatts (KW)
Power Factor Correction Primary Power
A modified spray transfer process that produces no spatter, because the wire does not touch the weld puddle
Pulsed MIG (MIG-P)
A modified TIG process appropriate for welding thinner materials
Pulsed TIG (TIG-P)
For this variation of spray transfer, the welding machine “pulses” the output between high peak currents and low background currents. The weld pool gets to cool slightly during the background cycle, allowing for welding in all positions on either thin or thick metals
Pulsed-Spray Transfer
Sequencing and controlling the amount of current, the frequency and the duration of the welding arc
Pulsing
A process in which two pieces of metal are joined by passing current between electrodes positioned on opposite sides of the pieces to be welded. There is no arc with this process
Resistance Spot Welding (RSW)
Welding a lengthwise seam in sheet metal either by abutting or overlapping joints
Seam Welding
Welding where the equipment controls only the electrode wire feeding. The welding gun movement is controlled by hand
Semiautomatic Welding
Protective gas used to prevent atmospheric contamination of the weld pool. It is obtained from the electrode outer coating, often called flux. Filler metal is
primarily obtained from the electrode core
Shielding Gas
Named for welding wire touching the base metal many times per second, can be used in all welding positions and on all thicknesses of metal. Some spatter is produced
Short Circuit Transfer
Metal particles blown away from the welding arc. These particles do not become part of the completed weld
Spatter
