welding final

What does OFC stand for?

 

Oxy-fuel cutting

While making a cut with OFC, the inner cones of the flame should be held how far away from the surface of the metal?

 

1/16" - 1/4"

What is required BEFORE making a good manual OFC?

Proper gas pressures

 

Neutral flame adjustment

 

Clean center hole in the tip

With OFC, what is the result of a preheat flame that is too small/low?

 

Travel speed of cut must be slower

 

It takes longer to make the cut

OFC: Slag that is hard to chip off the bottom of the plate occurs because:

Too much preheat

 

The cutting tip is dirty

 

Incorrect oxygen pressure

 

Wrong tip size for the metal being cut

OFW: What metal is easiest to weld with oxyacetylene?

 

Mild steel

With OFW, the size/diameter of the filler metal used has the following effect(s):

It can change the size of the weld bead

 

It can change the temperature of the weld puddle

The weld pool when OFW:

Has additional help against oxygen from the silicon deoxidizers that are in the filler metal

 

Is shielded from the atmosphere by CO2 gas

OFW: What should happen as one finishes the end of the weld?

Pause and add a little filler metal to fill in the crater

 

Pull the torch up/slant the torch at an angle to allow the puddle to cool but allowing the shielding gas to protect the molten metal

The gas that burns the hottest is:

Acetylene

Kindling temperature is:

 

The temperature at which metal burns

Steel melts at what temperature?

 

2700 deg F

What material(s) listed is READILY cut with OFC?

steel

Which of the following is (are) COMMON to both OFW and OFC?

Torch body

 

Neutral flame

 

Oxygen

Flashback can occur:

When the welding tip overheats

 

When the cutting tip overheats

 

When mixed fuel burns inside the torch tip and/or hoses

OFC: Kerf is:

 

The gap created by the diameter of the oxygen stream

What are the main advantages of OFC?

Portable

 

Low cost

 

OFW would be best for:

Small jobs or repairs

 

Plate 1/8 or thinner

Which of the following are weld discontinuities:

Anything that should not be in the weld area

 

Porosity

 

Craters

Mark all the statements that are true:

All GOOD welds should have a good appearance

 

Not all welds with good appearance are sound

Which filler is used for OFW?

R65

 

RG45

Which of the following are used as fuel gases for OFC:

MAPP or MPS

 

Propylene

 

Acetylene

 

Natural Gas

Propane is the most frequently used fuel gas.

false

Restricting the working pressure of ___________ helps reduce the risk of explosion.

 

Acetylene

Which drive roll is recommended for solid steel electrode?

 

Smooth V-Groove

When silicon combines with oxygen it floats to the top of the weld and forms _________ islands.

Silica

How does amperage influence penetration?

 

As amperage goes up, penetration goes up

When you have your helmet down and are in the process of welding, what is it that your eyes should be concentrating on so that you know if the weld will be the right size and quality?

 

The molten weld puddle

For GMAW, you were instructed to:

 

Use a push technique

If the gun nozzle has a lot of spatter stuck inside you might experience this:

Porosity

 

Lack of shielding gas coverage

What Current and Polarity are used for GMAW?

DCEP

Increasing the welding voltage has the most influence on what?

 

Increases the width of the weld bead

Which of the following give the most accurate depiction of a correct gas flow rate for GMAW?

 

25 SCFH

Power sources for GMAW are:

 

Constant Voltage

The root of a weld is opposite the:

Face

What does "Complete Joint Penetration" mean?

 

A completely filled groove weld

Autogenous means:

 

No filler metal

Vertical welding refers to:

 

Position

On a butt joint groove weld, amount of metal that protrudes above the top surface of the base metal on the side that the joint is being welded from is referred to as:

 

Reinforcement

Does the welding process to be used have any effect on the joint preparation?

Yes

The test position for a horizontal fillet weld is:

2F

What is the appropriate level of quality for a weld?

 

The quality of a weld should conform to the appropriate code or standard call out.

Check all that are discontinuities:

 

Undercut

 

Arc Strike

 

Overlap

Porosity is caused by:

Gas in the molten weld metal escaping to the surface as the weld cools.

 

Lack of shielding gas surrounding the molten weld puddle.

 

Clogged gas nozzle.

Which of the following is the primary cause of porosity?

Hydrogen

Can leaving the oxide layer (mill scale) on the weld joint lead to increased porosity in the weld?

yes

According to most welding standards, any indication of porosity is cause for weld rejection.

false

You might find a slag inclusion from:

Welding over the top of undercut from a previous weld bead.

Using a push technique with a process that produces slag.

Incomplete fusion is:

 

Areas were the weld metal does not mix with the base metal.

Undercut

 

Occurs at the toes of a weld.

Throat cracks are usually:

hot cracks

The best way to prevent a crater crack is:

 

When welding, stop at the end of the weld bead and allow the weld metal to fill in before extinguishing the arc.

What is the name of the discontinuity when the weld metal flows over the surface of the base metal (and does not fuse to the base metal) at the toe of the weld bead?

Overlap

What is the difference between a 'weld symbol' and a 'welding symbol'?

 

Weld symbol is just the symbol referring to the weld type and a welding symbol is the whole symbol including all the information.

What information is usually placed in the tail of a welding symbol?

 

Welding process

EXXXX is an example of the

 

Electrode classification for SMAW

Mark the primary purpose of the outer coating of the SMAW electrode:

 

Create gas shield for molten puddle

How many major groups of SMAW electrodes are there?

4

SMAW uses what type of power supply?

 

Constant current

A phenomenon caused by magnetic fields interfering with the electric arc.

 

Arc blow

When would PAC be used over OFC?

For higher production speeds

 

For cutting thin metals

 

When cutting non-ferrous metals

What type of power supply is needed for carbon arc gouging?

 

Same as SMAW

Which of the following correctly describe the HAZ for PAC? (mark all that apply)

Potentially hardened edges

Small HAZ compared to OFC

Which temperature most closely resembles the PAC temperature?

 

25,000°F

Check all the materials that can be cut with PAC: (mark all that apply)

Aluminum

 

Stainless steel

 

High carbon steel

Copper

In our shop, the plasma cutters use what type of orifice/plasma gas?

 

Compressed air

The CAC-A air/gas supply is:

 

Compressed air

A proper joint gap for brazing is:

 

.001 - .010"

Capillarity uses what scientific method to pull molten filler metal into a joint?

 

Surface Tension

A brazing filler metal is designed to use a eutectic point. What does that mean?

 

The filler metal will go from a solid to a liquid in just a small temperature rise.

Brazing and Soldering Fluxes: (mark all that apply)

Strip oxides from the metal's surface

 

Decompose when held at an elevated temperature for too long

 

Facilitate capillarity

 

Decompose when overheated

 

Activate when heated

Which of the following describes "lead-tin" alloy filler?

Soldering

What kind of power is in a typical residential house?

single

Mark the statement that is most correct about 3 phase power:

Power is created by:

 

3 phase power is more efficient than 1 phase power

Moving a conductor (copper wire) through a magnetic field

 

Moving a magnet through a conductor (copper wire).

Frequency (measured in hertz) has reference to (mark all that apply)

How many times current shifts from positive to negative and back in 1 second

 

AC

AC power is transmitted long distances by:

 

Increasing voltage and decreasing amperage