Machine Technology Flashcards
1
Q
What is the taper for national pipe taper threads?
A
3/4” per foot or 1/16th per inch
2
Q
What is the standard finish for pipe used in hydraulic service?
A
Pickled and oiled
3
Q
How can you check for a twist in a hose after you have installed it?
A
Look for a twist in the writing or the lay line
4
Q
How do felt seals reduce friction?
A
By absorbing oil
5
Q
Regarding primary seal face pressure, what can mechanical seals be?
A
Balanced and non-balanced
6
Q
Select all the correct secondary seal designs.
V-ring, PTFE wedge, O-Ring, U-cup, RTV urethane
A
V-Ring, O-ring, U-Cup, RTV urethane
7
Q
TorF. Rings 6-10 in a stuffing box are not particularly important in the sealing process
A
True
7
Q
What does the term repacking a valve encompass?
A
Remove, inspect and replace packing in the stuffing box.
8
Q
What must be done to disassemble threaded pipe?
A
Use two pipe wrenches and turn the pipe counter-clockwise
9
Q
When should a flare nut be installed on a length of tubing?
A
Before flaring
10
Q
TorF. Straight threads are commonly used in hydraulic systems?
A
True
11
Q
Select all the answers that explain why flushed gland seals circulate fluid around the seal face?
To Lubricate, To cool, To clean, To heat
A
To Lubricate, To cool, To clean
12
Q
TorF. Compression packing is used to seal shafts that have reciprocating, rotary, or helical motion
A
True
13
Q
TorF. Plug and ball valves require a full 360 degree turn to open or close fully
A
False
14
Q
What is the thread that has a spiral leak path if assembled dry?
A
NPT
15
Q
TorF. Weld outlet fittings are used to attach branch lines to a main pipe.
A
True
16
Q
TorF. Swing check valves must be mounted horizontally.
A
True
17
Q
What types of materials are used in the construction of bellows?
Metal
Rubber
PTFE
Fabric
A
Metal, Rubber, PTFE
18
Q
The heaviest wall copper tube used for plumbing has what letter designation and colour?
A
K, green
19
Q
Schedule 80 pipe differs from schedule 40 pipe because it has a
A
smaller id
20
Q
What is the RPM limited to when using a lip seal on a 2 inch unhardened shaft?
A
1500
21
Q
In a drawing, which of the following terms describes the calculated length of pipe required?
A
End to center, end to end, face to face not
22
Q
TorF. Reducing the number of fittings in a pipe system reduces the fluid turbulence in the system.
A
True
23
Q
TorF. Gas barrier seals use a stable film of gas in micro grooves to accomplish sealing.
A
True
24
A flexible hose with a 10,000 psi rating would have a burst pressure of:
40,000 psi 40:1
25
ToF. It is always good practice to use some sort of anti seize compound on the gasket when installing the gasket.
False
26
What type of hanger allow pipe to move up and down freely?
Spring
27
ToF. The ID is always the same for different pipe weights.
False
28
What should you do to a tube after it's cut and before you have completed the flaring process
Remove the burr?
29
ToF. There is no rubbing between faces of a gas lubricated seal.
True
30
ToF. The disc of a gate valve can be wedge shaped only?
False
31
What type of fitting is used for very high temperatures and/or pressures?
Welded
32
ToF. Seals can be both contact and non-contact
True
33
When joining two pieces of pipe together under 2 inches what is the most common welded joint?
Socket Weld
34
Too much closing force can cause what problems?
Loss of lubrication, premature wear and seal failure, High frictional heat, Loss of pressure, Higher seal face loading
Loss of lubrication, Premature wear and seal failure, High frictional heat, Higher seal face loading
35
ToF. Flow control valves should not be used for isolation purposes.
True
36
ToF. Non-contact seals are positive seals
False
37
Select materials that are commonly used for primary seal faces.
Ceramic, Titanium, Carbon, Silicone carbide, Tungsten carbide, Stellite, Bronze, Ni-Resist
38
ToF. The ends of hydraulic pipes are sealed and should no be opened until installation.
True
39
What does the valve marking WOG stand for?
Water, Oil, Gas
40
What are non-pusher type seals also referred to as?
Bellows
41
How should Teflon tape be wrapped if used on NPT pipe?
So the spiral tightens as the pipe is threaded together.
42
How many threads should show after you hand tighten a pipe fitting?
Two or three
43
ToF. Hose fittings are sized with a dash number the same as hose fittings?
True. Dash = # of 1/16ths
44
ToF. Reducing the number of fittings in a pipe system reduces the friction in the system and keeps the temperature of the fluid flowing in the system cooler.
True
45
How is seamless pipe manufactured?
Extruded
46
What are bellow seals commonly made from?
PTFE and Metal
47
Lip seals incorporate a _____ to maintain contact when there is no internal pressure present.
Garter spring
48
ToF. Ribbon packing should be compressed 50% before the next ribbon of packing is applied.
True
49
What type of material is commonly used for the construction of the bellows seal?
PTFE
50
ToF. Weld outlet fittings are used to attach branch lines to a main pipe.
True
51
Select all pipe end finishes.
Threaded, Plain, Bevelled, Grooved.
Threaded, Plain, Bevelled, Grooved
52
To find the travel for a 45 degree straight offset, multiply the amount of offset by:
1.141 or square root of 2
53
How tight should a flare fitting nut be tightened after it's made finger tight?
1/4 turn for tube sizes up to 5/8" and 1/8 turn for sizes over 5/8"
54
ToF. Victaulic joints are groove and clamp style.
True
55
ToF. Inconel is an example of a material used for the hard face of a mechanical seal.
True
56
Select all the standards used in Canada for pipe
ASTM, ISO, API, CSA
57
ToF. Butt joints are used when using compression packing on a pump shaft
True
58
ToF. ORB stands for o-ring boss
True
59
ToF. All valves should have pressure and temperature ratings on them
True
60
Flareless fittings are also known as compression fittings.
True
61
ToF. A diaphragm is a type of flexible moveable gasket
True
62
ToF. Safety relief valves are used in gas and steam systems and are vented to atmosphere.
False
63
Select the 5 sealing points of mechanical seals.
At the rotating element on the shaft.
Around the outside stationary face.
Between the lantern ring and the ribbon packing.
Between the packing and the stuffing box.
Between the rotating and stationary primary faces.
Between the shaft and sleeve.
Between the gland and the pump housing.
Between the extrusion ring and shaft.
At the rotating element on the shaft.
Around the outside stationary face.
Between the rotating and stationary primary faces.
Between the shaft and sleeve.
Between the extrusion ring and shaft.
64
ToF. Flareless fittings are more secure than flared fittings when they are exposed to vibration.
True
65
What does a cartridge seal provide?
All the necessary sealing components in a pre-assembled unit.
66
ToF. The handle on a ball valve indicated whether it is open or closed.
True
67
ToF. Lay lines on a hose are used to determine if the hose has been twisted
True
68
What type of pipe threads are used on hydraulic lines?
NPS
69
ToF. Most compression packing is infused with some form of lubricant in it's construction.
True
70
What should be taken into consideration in choosing a seal face material?
The corrosive properties of the liquid, the temperature and lubricity.
71
Where is the reinforcing put for vacuum hoses?
Inside the tube, embedded in the tube, outside the tube
72
What valve can be used for throttling?
Globe
73
ToF. Mechanical seals can accommodate some shaft misalignment?
True
74
Generally speaking tubing is limited to sizes under how many inches?
2
75
Which low speed oil seal can tolerate a lot of end float?
V-ring
76
The nearer you position the retainer to the stationary seal ring, the _______ the closing force exerted on the sealing faces
Greater
77
Pipes supports should.
All of the above
78
Select all the arrangements that can be found for double mechanical seals.
Face to Face, Back to Back, Tandem
79
ToF. Valve actuation can be done manually, hydraulically, electrically or pneumatically.
True
80
What is the chord length formula for laying out flange gasket holes?
Cord length equals bolt circle diameter times a chart factor.
81
Overseas fittings and North American fittings are compatible.
False
82
Sealing compound is used on what type of threads?
NPT
83
Hydraulic lines should not be made from?
Galvanized pipe
84
how are pressure hose sized?
by inside diameter in sixteenths given by dash number
85
The purpose of mechanical seal is to prevent leakage around a _____ shaft.
Rotating
86
Why should packing always be cut and never spiraled?
It creates a spiral leakage path
87
ToF. A diaphragm valve is used primarily is caustic and acid pipelines
True
88
ToF. Another name for non-pusher seals is bellows seals.
True
89
What are the advantages of non-contacting seals?
There is no friction, seal wear and speed limits
90
ToF. A ball valve is fully open when the handle is 90 degrees to the valve body
False
91
Hydraulic flared fittings have a flare angle of
37 degrees
92
ToF. Diaphragms can be used in valve actuators
True
93
ToF. The globe valve has a straight-line flow pattern through it
False
94
ToF. The faces of gas lubricated seals do not come into contact with each other while running.
True
95
ToF. Vacuum hoses are sized by ID in fractions of an inch.
True
96
When undoing flange bolts which one should be loosened first
Farthest from you
97
ToF. When used as secondary seal PTFE wedges are designed to be pushed against a rotating carbon face
True
98
ToF. Compression packing at times acts as a bearing
True
99
ToF. Metric pipe sizes are based on converted standard imperial sizes.
True
100
ToF. Lip seals can withstand pressures up to 200 psi
False
101
What valve can be used for throttling?
Globe
102
How can you minimize contamination due to assembly of pipe joints?
Use straight thread ORB fittings
103
ToF. Diaphragm valves can handle temperatures well over 300 deg C
False
104
What is the difference between the rating on a pressure hose and the rating on a vacuum hose?
Bursting pressure and collapsing point
105
ToF. Poorly supported pipes cause unnecessary stress and breakage.
True
106
ToF. PTFE is another term for teflon
True
107
ToF. "Balanced" mechanical seals are designed to utilized internal pressure and seal area to negate the effects of discharge pressure on the sealing faces.
True
108
ToF. Nominal pipe size and OD are the same thing.
False
109
An "o-ring" is an example of a secondary seal in a mechanical seal
True
110
What is the purpose of pipe dope?
To lubricate the threads when assembling, to seal the spiral leak path
111
ToF. Carbon yarn packing is used in applications where temperature is limited to 315 degrees C
True
112
What must primary seal faces be made from?
Dissimilar materials
113
ToF. A plug valve requires only a quarter of a turn to open or close fully
True
114
How is imperial tube sized?
Outside diameter in fractions of an inch, wall thickness in thousandths of an inch, working pressure in psi.
115
Most non-metallic tubing used in pneumatic lines limited to conditions of?
Not 145 PSi & 190 Deg F
116
ToF. Gas barrier seals use a stable film of gas in micro grooves to accomplish sealing
True
117
What is black iron pipe finish?
Coated in lacquer
118
ToF. Welded metal bellows seals can deform at higher speeds.
True
119
What does an o-ring extrusion ring do?
Prevents p-rings from getting extruded under high pressure
120
How is tubing sized?
OD
121
Which of the following is not important when selecting pipe fittings?
Same manufacturer as pipe
122
The dimensions in piping system drawings are commonly
End to centre?
123
Flared connections that have long-shouldered nuts are used to
Provide suport
124
An ORb fitting is used to transition from what?
Tapered threads to straight threads
125
ToF. Pressure relief and pressure safey valves open and function by manual operation only.
False
126
In general, what are metallic gaskets and seals used for?
For higher temperatures and pressures.
127
Select all the reasons hoses are used?
For very cold environments, When connecting moving parts, When extremely high temperatures are involved, When reducing the effects of vibration and shock
When connecting moving parts, When reducing the effects of vibration and shock
128
What are two types of closing mechanisms found on pusher seals
Single springs and multiple springs
129
Why do pipes have a mill certification?
So there is a paper trail if the pipe fails in process to track the problem.
All answers are correct. - Answer!
To ensure you are using the type of steel specified.
To determine the chemical analysis of the steel.
130
A pipe support that prevents vertical pipe from dropping through a floor is called
Riser Clamp
131
What is the main difference between single mechanical seals and double mechanical seals?
Single seals have one set of primary seals, double seals have two
132
ToF. The design of an angle valve increases the turbulence when compared to the flow pattern of the standard globe valve.
False
133
What should be done if fluid can get between a pump shaft and sleeve?
Use an o-ring
134
NPT fittings can be resued
Depends what for?
135
By what measure are all pipes up to 12" sized?
Inside diameter
136
"WSP" refers to the valve's working steam pressure
True
137
What is the purpose of the cover on a pressure hose?
To protect the inner hose from abrasion
138
ToF. Butterfly valves can be designed to withstand temperatures over 2000 degrees F
True
139
The diameter of metric tube is given in millimeters to how many decimal places?
2
140
Aluminum is used a material for metal compression packing
True
141
A groove worn in the harder primary seal face is an indicator of what?
Dirt particles and contamination have become lodged in the softer seal face because the seal faces have seperated.
142
Why are copper and brass not suitable for hydraulic piping?
Accelerate oxidation of the oil.
143
