Test 3 Flashcards
- T/F Both relief valves and safety valves are the two most common safety devices designed to prevent overpressure conditions in process industries.
True
________ is the abnormal rapid reciprocating motion of the movable parts of a relief valve in which the disc contacts the seat repeatably.
Chatter
______ is the pressure increase over the Maximum Allowable Working Pressure (MAWP) of equipment during discharge through the protecting pressure relief valve and is usually expressed as a percentage of the MAWP.
Accumulation
_______ is the pressure at which the relief valve starts to open.
Set Pressure
The sun is a pressure source for relief valves in thermal expansion relief valve scenarios.
True
T/F A relief valve will rapidly fully open (pop) when the set pressure is reached.
False
T/F The pilot-operated valve allows for more accurate control over the set pressure compared to a spring-operated relief valve.
True
A pilot-operated relief valve is ____ susceptible to chattering compared to a spring-operated relief valve.
less
A spring operated relief valve ______ require an external power source.
does not
Label the parts of the spring operated relief valve. A
Bonnet
Label the parts of the spring operated relief valve.
B
Spring
Label the parts of the spring operated relief valve. C
Disc
Label the parts of the spring operated relief valve. D
Adjusting Ring
Label the parts of the spring operated relief valve. E
Nozzle
Label the parts of the spring operated relief valve. F
Body
T/F In systems containing flammable fluids, the diverted fluid is usually routed through a piping system to a flare header or relief header.
True
This type of relief valve is designed to open when the temperature of the process fluid exceeds a certain temperature limit.
Temperature-Activated Relief Valve
Identify the bellows in the balanced bellow relief valve A
Guide
Identify the bellows in the balanced bellow relief valve B
Metal Bellows
Identify the bellows in the balanced bellow relief valve C
Disc Holder
If you require a relief valve that is used in a process where the fluid is dirty and contains particulate, you should use a ______ pressure relief valve.
Nozzle Type
With a pressure safety valve (PSV), when the set pressure is reached the PSV will ________.
Open Rapidly to full open
Name an application where a pressure safety valve is used.
Steam Boilers
Section VIII of the ASME Code covering pressure vessels requires pressure relief valves to have lifting levers on __________________________________
air, Steam and hot water (over 140°F) service
What are the two common sizes for thermal relief valves.
1” x 1” or 3/4” x 1” having minimum orifice area of 0.110 in squared.
A tank that has sun exposure has inlet and outlet valves that are often closed. The tank holds a liquid that expands when heated. Should the tank have a thermal relief valve?
Yes
Relief valves are sized based on the _______ area.
orifice
The API standard for relief valve orifice sizes are designated by _____.
letter
Which API orifice size has a bore dimension of 0.785 in2?
H
For a 4” x 6” relief valve, the outlet connection size is _____ inch.
6
A hard seat relief valve uses a _______ to ______ seat valve.
metal to metal
Name an application that a hard seat relief valve will be used in.
Extremely high temperature applications
T/F The composition of the sealing material in the internals of the relief valve will depend upon on the compatibility of media flowing through the valve.
True
T/F Pressure relief valves and safety valves should be mounted in the vertical position (upright with the spindle vertical).
True
T/F It is good practice to make the inlet piping a smaller diameter than the relief valve inlet size.
False
T/F For flanged relief valves, it is a good practice to tighten one side all the way down before tightening the other side
False
The nominal size of the outlet piping __________.
must be as large or larger diameter than the relief valve out size
T/F The outlet piping of a relief valve should always be supported to prevent damage to the relief valve.
True
Name the two common end connections for relief valves.
Threaded and flanged
Name two industries that use relief valves.
Chemical processing & Oil and Gas Industry
The symbol shown is a symbol is for a ______.
P&ID symbol for a relief valve
The symbol shown is a symbol is for a ______.
Pilot operated relief valve
T/F Rupture discs can be used multiple times.
False
What are the two most used pressure protection devices in industrial plants?
Rupture discs and pressure safety valves
T/F Rupture discs provide an instant response to over or under pressurization in a piping system.
True
T/F Relief valves and safety valves can fail to function against overpressure.
True
T/F Rupture discs can be used in combination with a pressure safety or relief valve.
True
T/F Rupture disc can be either round or square.
True
_______ acting rupture discs allow higher working pressures and tighter tolerances.
Reverse
Identify the domed rupture disc
Forward Acting
Identify the domed rupture disc
Reverse Acting
Name two materials that rupture discs are constructed from.
Carbon Steel and Stainless Steel
Name three industries where rupture discs are used.
Petrochemical, railroad and Chemical
Name the two ways in which rupture discs are installed.
Directly between flanges or inserted into a corresponding rupture disc holder which is then mounted between flanges
Name an application where a rupture disc is used in a primary relief option.
A pressure vessel with no permanent supply connection
Name an application where a rupture disc is used in a primary relief option. Can be used with pressure relief valves in parallel.
Rapid & large pressure rise where extremely fast action is required to prevent catastrophic failure.
Name a benefit of using a rupture disc upstream of a relief valve.
Protects the PSV/PRV from fluids containing solids, that may plug/damage the valves.
The burst pressure requested by the user is the ________ burst pressure.
specified
The accuracy of the rupture disc’s performance is known as burst _______.
tolerence
Name two advantages of a rupture disc.
Leak tight seal and High reliability
Name a disadvantages of a rupture disc.
Must be replaced after each occurrence
The P&ID symbol for a rupture disc is
b
T/F A check valve allows fluid (liquid or gas) to flow through it in only one direction.
True
What is the primary function of a check valve?
Protect mechanical equipment in a piping system by preventing reversal of flow by the fluid.
How are check valves labeled to show the proper direction of flow?
Typically have an arrow on its body to show the proper direction of the flow
What is cracking pressure?
The minimum upstream pressure required to open a check valve enough to allow detectable flow.
The most common check valve used in industry is the _______ check valve.
Swing
This type of check valve is designed to fit in tight spaces and is a good choice where a short length check valve is required.
Wafer check valve
T/F It is possible for foreign particles to get stuck between the check valve seat and disc.
True
Label the components of the wafer check a.
Plate
Label the components of the wafer check valve b.
Body
Label the components of the wafer check valve c.
Spring
Label the components of the wafer check valve d.
Plate Hinge Spring
Label the components of the wafer check valve e.
Spring Restraining Pin
Name three commonly used check valves.
Swing, wafer and ball
Wafer check valves can be installed in _____ positions.
both horizontal and vertical
T/F For systems with pulsating flow, a swing check valve is a good choice.
False
_______ are used in wafer check valves to assist the valve in closing and preventing reverse fluid flow.
Springs
Name two recommended guidelines for inspection of swing check valves.
Check for leakages and look for any sign of corrosion, rust and wear
T/F Swing check valves are prone to water hammer issues.
True
T/F A wafer check valve can be inspected while in service.
False
The only moving part of a ball check is a(n) ___________.
Spherical ball
T/F For a ball check valve, the ball is available in different weights to match the application.
True
Label the parts of the piston check valve a.
Springs
Label the parts of the piston check valve b.
Spacers
Label the parts of the piston check valve c.
Seating Surfaces
Label the parts of the piston check valve d.
Seating Surfaces
Label the parts of the piston check valve e.
Valve Stem
Label the parts of the piston check valve f.
Valve Bonnet
Label the parts of the piston check valve g.
Cage
Label the parts of the piston check valve h.
Main Plug Valve
This part of the piston check valve is used to help in closing the valve immediately when suction pressure starts reducing.
The Spring
This type of check valve has a short linear stroke and spring return action combine to close the valve prior to flow reversal which effectively eliminates the shock and water hammer.
Silent Check Valves
What is the likely cause of a chattering or vibrating silent check valve.
Fluid moving at a high velocity
The P&ID symbol for a check valve is ______.
b
What is a sampling valve used for?
For taking a representative portion of a fluid (gases, liquids, solids, or slurries) from a live process to test typically for the purpose of identification, quality control, or regulatory assessment. Also can be used of or injecting a substance into a process.
Name the three common sampling valve end connections.
Flanged, Welded and Threaded
T/F In the chemical industry, a sample must not contain remains of previous batches that may have stayed in the valve’s dead space.
True
What is the problem with using a ball valve for obtaining a representative sample?
Liquid stays in the ball and the next time it is opened, the liquid flows first. The valve must be flushed before the sample is taken.
T/F When sampling hazardous chemicals, it is important that the operator is not exposed to toxic fumes or vapors.
True
What is the advantage of using a sampling valve with a piston?
The valve ensures that new product samples are always taken with no prior sample material remaining.
In the natural gas industry to take a representative sample, the sampling probe should _____.
extended to the center third of the pipe
Name two components that are commonly added to a sampling probe in the natural gas industry.
Pressure regulator and membrane filter
What issue can liquid pose when included in the gas sample?
Impact the accuracy of the compositional analysis and damage the analyzer.
What does the A+ manifold have to monitor the pressure?
Pressure gauge and ball valve
Define an actuator.
An actuator is a device that converts energy into a mechanical force to enable movement of a valve.
Name three sources of energy for an actuator.
pneumatic (compressed air), pressure, hydraulic (oil) pressure or electric current which moves the internal mechanical parts of the actuator.
Provide the six basic functions that a valve actuator performs.
Move the closure component position, maintain the closure component position, seat the valve with sufficient torque, have a failure mode, provide proper rotational capabilities, Operate the appropriate speed.
In a single-acting actuator, what provides the power to return an actuator to its original position?
A spring provides the power to return the actuator to its original position.
T/F A double-acting actuator has ports on both sides of the piston.
True
What is the largest issue with electrical actuators?
They can overheat if there are extreme changes in duty cycle.
The amount of torque generated by a hydraulic actuator is ____.
High
What industry typically uses gas-over-oil actuators?
Natural Gas Industry
Name two types of valves that rotary actuators are used with.
Gate and Globe
Name the two main styles of linear actuators.
Diaphragm and piston (cylinder)
In direct-acting actuators, air enters the _____ area of the diaphragm.
Top
Direct-acting actuators are suitable for _______ applications.
Fail Open
Diaphragm actuators are typically used in _______ applications.
Throttling
Name two industries that use diaphragm actuators.
Power, oil & gas, process.
Indirect-acting actuators are suitable for _______ applications.
Fail Closed
Name the two supply pressure ranges for diaphragm actuators.
3 to 15 psi or 6 to 30 psi
Label the parts of direct acting diaphragm actuator 1.
Loading Pressure Connection
Label the parts of direct acting diaphragm actuator 2.
Diaphragm Case
Label the parts of direct acting diaphragm actuator 3.
Diaphragm
Label the parts of direct acting diaphragm actuator 4.
Diaphragm Plate
Label the parts of direct acting diaphragm actuator 5.
Actuator Spring
Label the parts of direct acting diaphragm actuator 6.
Actuator Stem
Label the parts of direct acting diaphragm actuator 7.
Spring Seat
Label the parts of direct acting diaphragm actuator 8.
Spring Adjuster
Label the parts of direct acting diaphragm actuator 9.
Stem Connector
Label the parts of direct acting diaphragm actuator 10.
Valve Stem
Label the parts of direct acting diaphragm actuator 11.
Yoke
Name two advantages of pneumatic diaphragm actuators.
Simplicity of operation and low maintenance
Name a disadvantage of a pneumatic diaphragm actuator.
Cost & maintenance of a compressed air system. Improperly maintained air system can provide air that is contaminated by oil or lubrication, leading to downtime and maintenance.
Piston actuators take supply pressure up to ____ psig
150
T/F Piston actuators are used when the thrust of a diaphragm actuator is too short to move the valve.
True
T/F Piston actuators can generate higher thrust due to the ability to take higher inlet supply pressures.
True
Label the parts of the piston actuator 1.
Loading Pressure Connection
Label the parts of the piston actuator 2.
Piston
Label the parts of the piston actuator 3.
Piston Seal
Label the parts of the piston actuator 4.
Cylinder Closure
Label the parts of the piston actuator 5.
Cylinder Closure Seal
Label the parts of the piston actuator 6.
Seal Bushing
Label the parts of the piston actuator 7.
Stem Connector
Name the type of actuator for the P&ID symbol
Electric or Motor
Name the type of actuator for the P&ID symbol
Diaphragm
Name the type of actuator for the P&ID symbol
Hydraulic
Name the type of actuator for the P&ID symbol
Piston
Name the type of actuator for the P&ID symbol
Electro/Hydraulic
Amount of torque to unseat an initially closed valve.
Breaking Torque
Amount of torque that leads to a valve being fully closed.
Closing Torque
Design to close a valve automatically in event of system failure.
Fail Closed
Design to open a valve automatically in event of system failure.
Fail Open
Design to have a valve stay in current position in the event of a system failure.
Fail Last Position
Air supply pressure required to operate a pneumatic actuator.
Supply Pressure
The material flowing through a valve.
Media
Throttling flow by varying the valve position between open & closed.
Modulating
Linear distance from the center of rotation upon which a force acts to produce torque.
Moment arm
Basic full open or full closed operation to start or stop flow.
On/Off Service
Force required to operate a valve expressed in foot-pounds
Operating Torque
Set of electrical contacts that are activated mechanically at a preselected position.
Limit Switch
Amount of force required to operate the control mechanism (valve)
Torque
The mechanism used to open and close a valve is known as ________.
actuator
The capability provided to actuators that allows the manual positioning of the actuator is known as a ___________.
Manual Override
The maximum amount of torque that can be implemented on a valve train before it malfunctions or is damaged is known as the __________.
MAST Maximum Allowable Stem Torque
The percentage of time a device is allowed to operate over a given period of time and is expressed in a percentage is known as _______.
Duty Cycle
A code established for electrical components by the National Electric Manufacturers Association is known as the _____ Rating.
NEMA
Identify the National Electric Manufacturers Association rating for the following electrical accessory enclosure applications - Indoor use and protects components from contact
NEMA 1
Identify the National Electric Manufacturers Association rating for the following electrical accessory enclosure applications -Indoor/outdoor use that is watertight and dust tight. Protects from windblown dust and rain.
NEMA 4
Identify the National Electric Manufacturers Association rating for the following electrical accessory enclosure applications - Indoor/outdoor use that is watertight and dust tight. Protects from windblown dust and rain and is corrosion resistant.
NEMA 4X
Identify the National Electric Manufacturers Association rating for the following electrical accessory enclosure applications-Explosion proof rating (Class I, Division 1, Groups A, B, C, and D) for an area that will contain gasoline or naptha.
NEMA 7
Identify the National Electric Manufacturers Association rating for the following electrical accessory enclosure applications - Explosion proof rating (Class II, Division 1, Groups E, F, G) for an area that will contain coal, coke dust, or flour.
NEMA 9
A machined coupling and plate, spool, or length of rectangular tubing designed to adapt an actuator to a valve is known as a __________.
Mounting Bracket
The maximum temperature of the flow media that is used in the selection of the proper valve material for the application is known as _______.
Maximum Service Temperature
The temperature of the air surrounding the actuator is known as the _________.
Ambient Temperature
This type of actuator uses compressed air or liquid to move the actuator in one direction and relies on a spring to return the actuator to its original position.
Single Acting
This type of actuator uses compressed air or liquid to both open and close the valve.
Double Acting
Name the two main types of actuators.
Rotary and Linear
T/F The most common manual operator on smaller quarter-turn valves is the basic lever.
True
On small valves where leverage is not needed, ____ shaped knobs are often used
these may be replaced by ovals, tees, or other
T/F Some manual levers have a means to lock them in place.
True
A lever with a _______ is also known as a dead man’s lever.
Spring Return
What purpose does the gearbox (gear assembly) serve with the hand wheel to operating the valve?
Increases mechanical leverage
Hand wheels with a gear assembly are commonly found on ball and butterfly valves larger than ___ inch
8
What accessory is added to access a large valve that is located out of reach from the ground?
Chain Wheel
A manual valve where the valve position needs to be known are equipped with a _______.
Position indicators
