Review Questions - Brazing

Question 1

What is an acceptable joint clearance for brazing?

1. 1.0mm (0.039”)
2. 0.03mm (0.001”)
3. 0.5mm (0.020”)
4. 10mm (0.390”)

Answer 1

0.03mm (0.001”)

Question 2

Which filler alloy allows copper brazing without flux paste?

1. copper-phosphorous alloy
2. silver-cadmium alloy
3. nickel-chromium alloy
4. gold-copper alloy

Answer 2

copper-phosphorous alloy

Question 3

When the joint gap is wide:

1. the brazed connection is weak.
2. the torch oxidizes the filler wire.
3. the flux will not flow over the parts.
4. the parts must be post braze annealed.

Answer 3

the brazed connection is weak.

Question 4

When torch brazing steel alloys:

1. the parts must be acid etched.
2. natural gas/oxygen cannot be used.
3. the parts must melt the filler.
4. the parts must be post-braze annealed.

Answer 4

the parts must melt the filler.

Question 5

what is the purpose of a brazing flux?

1. to prevent corrosion after joining
2. to chemically clean the joint surface
3. to fill the gap between loose parts
4. to make a mechanical connection

Answer 5

to chemically clean the joint surface

Question 6

At what temperature does brazing take place?

1. lower than soldering
2. same as soldering
3. above 840 °F (450 °C)
4. minimum of 1,000 °F (538 °C)

Answer 6

above 840 °F (450 °C)

Question 7

What does the brazing of copper to copper material require?

1. filler rod containing phosphorous
2. bag-1 filler rod with flux
3. capillary action
4. filler rod containing high levels of silver

Answer 7

filler rod containing phosphorous

Question 8

When does capillary action take place?

1. when welding copper to copper
2. when you have joints with a small gap
3. above 1,000 °F (538 °C)
4. only occurs with the use of flux

Answer 8

when you have joints with a small gap

Question 9

Which filler rod will fill a wide gap?

1. BCuP-3
2. only filler rods high in silver content
3. BAg-20
4. ER70S-2

Answer 9

BCuP-3

Question 10

How could you prevent internal oxide flaking when brazing copper lines together?

1. perform proper cleaning techniques, using sand cloth and flux
2. purge lines with nitrogen
3. use filler alloys high in silver content
4. purge lines with argon which is less expensive than nitrogen

Answer 10

purge lines with nitrogen