Shop theory Flashcards
Lap seam allowance?
1W
Groove seam allowance?
3W
Hammerlock allowance?
3W
What type of seam is an elbow seam?
Circumferential
Allowance for a female pittsburg?
15/16”
Male pittsburg allowance?
1/4”
Formula for stretchout?
Diameter x 3.14
What is the purpose for the bead on a pipe?
Add strength and as a stop for the pipe connected to it
What type of seam travels the length of the fitting?
Longitudinal
Formula for small end?
Minus 7MT
How is small end identified?
With a notch
What allowance is added to the net pattern for a slip and drive connection?
1/2”
Ideal length to width ratio for duct?
1 to 1
To what standard is ductwork constructed?
SMACNA
How many views are required to develop the mitre line on a round tee?
2
In which direction should you follow when resistance welding?
Outward to avoid bulging and buckling
What is a crimp used for on a pipe?
Aid in the joining of fittings
The pitch between fasteners is?
The spacing
The 3 methods used to divide a stretchout into 12 equal spaces?
Sloped rule, using dividers and mathematically
What is done to a fish pattern to ensure it is perfect or true?
Truing up the pattern
What is used on a pattern to ensure it finishes at the correct angle?
Centreline
How is the type of seam to be used, determined on a fitting?
Material thickness and pressure class
How many methods are there to developing an offset?
4
Name 3 measurements that are required to develop an elbow?
Throat radius, opening (diameter) and mitre angle
What is the throat radius dimension on a full throat 4” 90?
4”
What is the centreline radius dimension on a full throat 5” 90?
7 1/2”
What are the sections of an elbow called?
Gores
How many patterns are required to lay out a 5 piece, 90?
1
What must be considered when laying out and fabricating a 90 degree elbow?
Airflow
Name 2 turning machines that can produce an offset circumferential lap seam?
Offset lap and burring
What 3 dimensions must be known before developing the elevation view of a round offset?
Offset amount, opening size and vertical height
What is the stretchout for a 4” 90?
12 9/16”
What is the cut or blank size for a 5” SE with a 1/2” lap seam x 48” H?
16” x 48”
What is the cut or blank size for a 7” SE with a 1/4” groove seam x 24” H?
22 9/16” x 24”
What seam travels around a fitting?
Circumferential
What fitting is used to join spiral pipe?
Beaded sleeve joint, coupler, connecting collar
Which 90 is better for airflow-2 piece or a 5 piece?
5
Which notch removes material that may come in contact with a Pittsburg connection?
Transfer of angle notch
The formula for developing the mitre angle can only be used on 90 degree elbows, true or false?
False
Up to what distance are light rays dangerous?
50’
All compressed gas cylinders must have what type of label?
WHMIS
Welding lenses will protect your eyes from what percentage of harmful rays emitted during the welding process?
99%
3 components necessary for a fire?
Heat, fuel, oxygen
What is the maximum safe working pressure for acetylene gas?
15 psi
3 basic modes of metal transfer with gas metal arc welding?
Spray transfer, short circuit and globular
3 types of drive systems in GMAW
Push, pull, push pull
What is the primary function of the shielding gas when MIG welding?
Protect weld from atmospheric contamination
Flow rate for CO2 and Argon?
20 CFH
What can happen to a weld if travel speed is excessive?
Porosity
Why would you use blinds, screens or shields when welding?
Protect other people
When are transitional fittings used?
When duct size changes are necessary
What does FOB refer to?
Flat on back (bottom)
If duct is to have a raw connection, how much allowance is added to the length?
No allowance is added
What do you call a pattern that has allowances added to it?
Gross pattern
What do you call a pattern that has no allowances added to it?
Net pattern
What method can be used to calculate the length of a side rather than measuring off a pattern?
Pythagoras theorem
When cutting the hole in the body of a pipe tee, you should cut directly on the line you traced, true or false?
False
After laying out a pattern, what should be done prior to cutting it out?
Label airflow direction, number of pieces and centreline
Why are gore sections left together when rolled?
To ensure all pieces have the same curvature
True or false-an offset only needs the first gore developed?
False
Name 3 types of light rays given off by the torch and electric arc when welding?
Ultraviolet, infrared, visible and invisible light rays
What does GMAW stand for?
Gas metal arc welding
Best type of clothing to protect yourself when MIG welding?
Leather
What is used to indicate weld style on a blueprint?
Welding symbols
Name 3 types of malfunctions with oxyfuel equipment?
Backfire, flash back, burn back
What type of hammer is used to stretch the flange on a tee stub?
Riveting hammer
When welding, what controls the current?
Wire speed
What will change if the wire speed is increased when welding?
Amps
When assembling the sections of an elbow, in which direction should the gores be put together?
From SE (small end) to BE (big end)
What is the bevel on a welded pipe used for?
Root weld
What turning machine is used for making round pipe?
The adjustable slip rolls
What tool is used in shop to transfer the lengths of element lines from a view to a pattern?
Dividers
How are GMAW gun and cable assemblies rated?
Current carrying capacity
What component directs shielding gas onto the weld zone to prevent atmospheric contamination?
Nozzle
When rolling a pipe through turning rolls, what can be done to prevent flat spots?
Rotate project with each successive pass
What can happen if an elbow is fabricated with the seams in the incorrect orientation?
Turbulence
What does a regulator on a gas cylinder do?
Reduces source pressure to a constant working pressure
What is another way to describe the work lead connection on a welder?
Ground connection
When should a contact tube on a welding gun be replaced?
Electrode isn’t coming out or you are experiencing an erratic arc
What type of rolls on a rotary machine produce a bead used for strength and the stoppage of another pipe or fitting?
Beading rolls
What is the term used to refer to the first pass in welding?
Root bead or stringer bead
Why is a bevel put on a pipe?
To prepare the ends for welding
On what type of joint is a groove weld used?
Butt joint
What is the minimum number of pieces required to fabricate a transitional fitting with no flat sides?
4
