Valves, Pipe Fittings and Piping Flashcards
what is the function of a check valve?
to permit the flow of the fluid in one direction only
a gate valve is an example of what class of valves?
stop valves
what is the most common stop valve?
globe valve
what is the purpose of a bridge wall marking on a glove valve?
indicate the direction of flow
what type of valve is always open or always closed, and does not regulate fluid flow?
gate valve
what is meant by the term rising stem gate valve?
both the gate and the stem move upward when the valve is opened
what prevents gate valves used in high pressure steam systems from binding?
flexible gates
what are the disks and seats of valves used in high temperature steam systems surfaced with?
satellite
what type of valve is shaped to hold a cylindrical or tapered plug?
plug valve
what are plug valves commonly used for?
petcocks on auxiliary machinery
what type of valve is a combination gate valve and plug valve?
piston valve
what determines the tightness of a piston valve?
the closeness of fit between the piston and the inside of the cylinder
what type of valve is used to make relatively fine adjustments?
needle valve
what is the needle valve installed on an auxiliary turbine used for?
as an overload nozzle
what type of valve is light in weight, takes up less space than a gate or globe valve, and is relatively quick acting?
butterfly valve
how far must a butterfly valve be rotated to pen or close the valve?
1/4 turn or 90 degrees
what type of seat does a butterfly valve have?
resilient
what type of check valve, does the disk move up and down in response to changes in the pressure of incoming fluid?
lift check
what type of check valve, does the disc move in an arc to open or close the valve?
swing check
on a stop check valve, the maximum lift of the disk is controlled by?
the position of the valve stem
what type of valve opens automatically when the pressure in the line or in the unit becomes too high?
relief valve
what prevents a relief valve from lifting at normal operating pressure?
spring tension
how are relief valves set?
by the adjusting screw or adjusting nuts
at what pressure does the combination exhaust relief valve lift?
2 psi above auxiliary exhaust line pressure
what type of valve, gives an audible warning to the operator, when it lifts?
sentinel valve
what are two opposing forces on a spring loaded reducing valve?
the downward force of the spring; the upward force of steam pressure
on a spring loaded reducing valve, what determines the position of the auxiliary valve?
position of the controlling diaphragm
automatic unloading valves are installed to exhaust to what major components?
main and auxiliary condensers
what is the function of an unloading valve?
to discharge steam from the auxiliary exhaust line to the condenser whenever the auxiliary exhaust exceeds 15 psi
what comments is used when it is necessary to take suction from one of several sources and discharge to another unit or several units of the same or a separate group?
valve manifold
what allows an operator certain valves from distant locations?
remote operating gear
what is the cooling source for the inline desuperheater?
feedwater
what device is installed in steam lines to drain condensate from the lines without allowing steam to escape?
steam trap
what type of steam traps are considered to be mechanical type?
ball float and bucket type
how is the operation of a bellows type steam trap controlled?
by the expansion of the vapor of volatile liquid is enclosed in the bellows
what type of steam trap operates under the principle that hot water under pressure flashes into steam when the pressure is reduced?
impulse
what is the only moving part in an impulse steam trap?
the disk
constant flow drain orifices are used in what systems?
150 psi or above where condensate load and pressure remain neat constants
what type of steam trap relies on variable density of condenser?
orifice
what type of steam trap uses dissimilar metals to operate?
bimetallic
where can installations and other information be found pertaining to flange shields?
NSTM 505
what are two types of piping expansion joints used onboard ship?
sliding and flexible type
what type of piping expansion joint absorbs motion by the movement of a bellows or some similar device?
flexible type
what does a valve that has a marking on the body 2000 WOG indicate?
valve is suitable for water, oil and gas service at 2000 psi
how is tubing identified in the Navy?
by outside diameter (OD) and by actual measured wall thickness
what is the composition of copper nickel alloy tubing used onboard surface ships?
90 percent copper and 10 percent nickel
what are two classes of packing and gasket joints?
moving and fixed
what type of joint uses gasket material?
fixed
what type of joint uses packing material?
moving
a fixed joint is identified by the first digit in the symbol number, which would be?
two
a moving joint is identified by the first digit in the symbol number, which would be?
one
what is used to identify each type or style of packing and gaskets?
symbol number
what does the second digit of the symbol number indicate?
packing or gasket composition
how can practically all shipboard packing and gasket problems be solved?
by proper selection from the packing and gasket chart
low pressure packing must never be used to pack what type of system valves?
high pressure
what type of packing is constructed of 100 percent graphite?
Corrugated ribbon packing (CRP)
what lubricates the corrugated ribbon packing?
graphite
what kind of warning stickers must be affixed to all corrugated ribbon containers?
WARNING: CRP conducts electricity
what is the purpose of using graphite filament yarn (GFY) for the first and last packing rings on valves packed with corrugated ribbon?
they are used as anti extrusion rings to prevent the corrugated ribbon packing from being forced out of the stuffing box
what systems do not sue corrugated ribbon packing?
fuel oil and lube oil systems
how is the outlet temperature of the inline desuperheater controlled?
by thermostatic and diaphragm control valve
where can detailed information on the selection of insulation, lagging, and fastening be found?
NSTM 635
a tubular product is called pipe if its size is identified by what?
Iron pipe size (IPS) and by reference to wall thickness schedule of piping
how are flanges installed in nonferrous systems?
by brazing
how are steel flanges installed?
by welding
when removing lagging, if you are unsure of what material you are working with, who should you contact immediately?
your supervisor
on ships with steam atomization, what is used to lag the atomization piping at the burner front?
epoxy coating
what are three positions of the combination exhaust relief valve?
normal, relief and safety
what position of the combination relief valve is used, when performing turbine overhaul?
safety position
