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What function are butterfly, ball, plug, and swing check valves?
rotary motion, they move along an angular or circular path.
Rotary motion valves that require only 90' turn from full open to full closed are classified as 1/4 turn valves.
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Define Valve Disc.
the part that controls the flow through the valve body. Ball valves and plug valves have either a ball or tapered plug config. for a disc.
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Name the valve type.
The valves have rectangular ports through the plug and body. The area of the port is either equal to 100% of the area of standard pipe or restricted
rectangular pipe
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Name the valve type.
The area through the valve is equal to or greater than the are of standard pipe.
100% area or full port
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Name the valve type.
The area through the valve is less than the area of standard pipe. Can only be used in applications where restriction of flow is not important.
Standard opening.
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Name the valve type.
The valve has a full round opening through the plug and body, or the same size and area as standard pipe.
round port
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Diamond port characteristics?
all diamond port valves are restricted flow types.
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List typical valve trim.
seats, discs, glands, guides, spaces, bushings, springs
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Define Galling.
the tearing of the surface that occurs when two pieces of metal slide across each other under high contact stresses
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What are gate, globe, diaphragm, releif valves classified as?
linear motion
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What are the class numbers for valves based on?
the pressure-temp ratings of the materials used.
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What is the S or SWP rating on a valve related to?
for service with steam at saturation temperature.
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What term describes the items mounted on the bonnet of a valve?.
upper works
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What type of closure is desired when a valve is specified to be constructed to the API 6D code?
bubble tight service, zero leaks
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What is the purpose of the machined flange area on the valve stem immediately above the key in an upper entry ball valve?
upper side of the flange is seated against a stem thrust washer to reduce torque, prevent galling, and provide secondary stem seal.
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What is the feature of Y pattern and angle pattern globe valves that makes them good for blowdown service when sludge is in the system?
Can be designed with self-scouring seats
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Why are ball valves not recommended for use with fluids that contain sharp particulate matter?
sharp particulate matter can settle or be trapped in the body cavities and create wear, leakage or valve failure.
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A velocity of one foot per second will create a pressure shock of ___ psi against the surface of the closed disc in the check valve.
60
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What is the MSS?
The Manufacturers Standardization Society of the Valve and Fitting Industry.
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What type of service is specified for the rated working pressure on bronze and iron body valves?
non-shock service.
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What condition in a system would most likely require the use of a tilting disc check valve?
low velocity flow
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What does a backseating do on a valve?
to isolate the stuffing box if tightening the packing gland will not stop a leak around th valve stem until it is safe to repair the packing
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What three pieces of info on a cast or forged steel valve are most important?
model number, serial number, heat numbers
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What special feature might be required for a gate valve installed in a vertical line?
drain valve tapping above the disc.
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How should the joints of successive rings be set into a stuffing box?
staggered and kept at least 90's apart.
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Which of the following ANSI/FCI class is known as a soft seat classification?
6
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Which of the following best describes a pinch valve?
An air to close actuator is used for service where the valve is normally in the open position
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What is the cause when a hand wheel on a gear operator will not turn?
one or more teeth broken on gears
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