WELDING

Question 1

Even though tungsten inert gas (TIG) welding is the accepted welding method for modern aircraft, you need to understand basic gas welding before learning these advanced techniques.
- This includes knowledge of the gases and equipment used, as well as equipment set-up, operation and shutdown.
• Gas welding, more than most aspects of airframe
maintenance, requires constant attention to safety
practices and proper use of safety equipment.

Answer 1

BASIC WELDING

Question 2

To produce enough heat to melt metal, a combustible gas like acetylene is mixed with oxygen.
- Other gases,
such as Propane,
Natural gas,
Methy-lacetylene-
propadiene (MAPP) gas, and Hydrogen are used primarily for cutting or in the Soldering/Brazing processes.

Answer 2

Gases

Question 3

samples of gases

Answer 3

propane, natural gas, methy-lacetylene propadiene

Question 4

A heavy gas, with a disagreeable odor, acetylene becomes unstable at pressures of 15 psi or higher.
- At 30 psi, the slightest amount of heat generated by friction of acetylene against the atmosphere will cause it to explode.
- The normal operating pressure for most acetylene welding is 4 to 8 psi.

Answer 4

Acetylene gas

Question 5

a colorless, odorless, tasteless gas that comprises 21 percent of the volume of the earth’s
atmosphere.
• In welding, is used to support combustion.
• must never be used in the presence of petroleum-based substances because of the danger of a fire or explosion.

Answer 5

Oxygen

Question 6

this ——- is relatively rich in acetylene

Answer 6

carbonizing flame

Question 7

from the welding torch changes as the volume of oxygen relative to the acetylene is increased.

Answer 7

flame color and pattern

Question 8

The intensity of the heat continues to increase with additional oxygen until the optimal mixture, and a ————- is reached.

Answer 8

Neutral Flame

Question 9

How hot is a neutral flame

Answer 9

6,300 F

Question 10

An ——— is used for cutting

Answer 10

oxidizing flame

Question 11

types of welding flames

Answer 11

neutral flame
oxidizing flame
carbonizing flame

Question 12

It is essential to understand the operation and safety practices for this

Answer 12

equipment

Question 13

oxyacetylene welding equipment includes

Answer 13

regulators, hoses, torches and lighters, goggles and gloves

Question 14

When using welding equipment, it is essential to follow proper safety procedures.
- The gases can be highly explosive and are under extremely high pressures that can be dangerous if not handled properly.

Answer 14

equipment setup

Question 15

The gas cylinders are shipped with protective caps which are threaded to cover the tank’s gas valves.
• The tank caps protect the gas valve from being broken if a tank falls over.
- A broken valve would turn a fully charged bottle into an uncontrolled rocket.
- Gas cylinders must always be locked or chained into a
holding stand
on either portable or stationary bottle
stations.
• High pressure cylinders used to transport and
acetylene must contain acetone.
Attaching the Regulators

Answer 15

Handling Gas Cylinders

Question 16

To attach a regulator, remove the protective cap from the cylinder and open the valve slightly to blow out any dirt particles that may be in the fitting.
- Close the valve and attach the regulator, taking care not to cross-thread the regulator union nut.

Answer 16

Attaching the regulators

Question 17

What color is oxygen hose

Answer 17

green

Question 18

what color is acetylene hose

Answer 18

red

Question 19

• A welder must learn to control a molten ——— without using a filler rod.
- Practice running a puddle without a filler rod before attempting an
actual weld
with a filler rod.
• A good puddle should
show a rippled
penetration on the bottom side of the plate.
• If the penetration is not deep enough, it is because the torch is moved too fast or the flame is not hot enough.

Answer 19

Puddle

Question 20

• An oxyacetylene flame can be used to cut steel with unrivaled ease.
- The cutting torch is similar to an oxyacetylene-welding torch with an additional valve that allows a stream of high-pressure oxygen to flow directly to the work from a hole in the center of the nozzle.
- Surrounding this oxygen hole is a series of pre-heating holes.
• With sufficient oxygen pressure and the right size torch tip, an oxyacetylene cutting flame can be adjusted to cut steel over a foot thick.
• The cut made by an oxyacetylene cutting torch is known as a
Kerf.

Answer 20

oxyacetylene cutting

Question 21

Parts of oxyacetylene cutter

Answer 21

Cutting oxygen lever
oxygen needle valve
acetylene needle valve
preheat orifice
cutting oxygen orifice

Question 22

what type of flame is used primarly in welding aircraft steel

Answer 22

Carbonizing flame

Question 23

what is the purpose of the additional vavle in any oxyacetylene cutting torch

Answer 23

To release high pressure oxygen for cutting

Question 24

what should the welder learn to control without using a filler rod

Answer 24

The puddle

Question 25

what is the final step when shutting down gas welding equipment

Answer 25

Hang up the torch and hose

Question 26

Methy-lacetylene-propadiene (MAPP) gas, and Hydrogen are used primarily for cutting or in the

Answer 26

Soldering/brazing processes

Question 26

A heavy gas, with a disagreeable odor, acetylene becomes unstable at pressures of

Answer 26

15 psi

Question 26

At—- psi, the slightest amount of heat generated by friction of acetylene against the atmosphere will cause it to explode.

Answer 26

30 psi

Question 26

The normal operating pressure for most acetylene welding is

Answer 26

4 - 8 psi

Question 27

The actual puddle movement is accomplished by keeping the hot cone at the torch tip about ——away from the base metal and slowly moving the tip in a small circular motion.

Answer 27

1/4 Inch

Question 28

Shutting Down the Equipment

Answer 28

1. Shut off the flame by closing the acetylene needle valve on the torch.
2. Close the oxygen needle valve on the torch.
3. Close the acetylene cylinder valve.
4. Close the oxygen cylinder valve.
5. Open the acetylene valve on the torch to drain the acetylene hose and regulator. This removes pressure on the regulator’s working-pressure gauges.
6. Turn the acetylene-regulator adjusting screw to the left to relieve pressure on the diaphragm, and then close the torch acetylene valve.
7. Open the torch oxygen valve, drain the oxygen hose and regulator.
8. Turn the oxygen-regulator adjusting screw to the left to relieve the diaphragm pressure. Then close the torch oxygen valve.
9. Hang up the torch and hose properly to prevent hose or torch damage.

Question 28

The recommended method is to——————fluid on each of the fittings while there is line pressure in the system.

Answer 28

Brush a commercial leak fluid

Question 29

Do not use a soap solution, since most soaps contain petroleum compounds.

Answer 29

Do not use a soap solution, since most soaps contain petroleum compounds.

Question 30

If detecting a leak, gently tighten the fitting. If it still leaks, bleed the system, undo the fitting, check for dirt, reconnect, and check for leaks again.

Answer 30

If detecting a leak, gently tighten the fitting. If it still leaks, bleed the system, undo the fitting, check for dirt, reconnect, and check for leaks again.