Chapter 11 and 12

What gases are produced by the combustion of oxyacetylene flame?

CO2 and H2O

describe the acetylene hose and regulator nut and its threads

Acetylene hose- inner layer is a very good grade of gum rubber Very flexible and light Size to be used depends on the size of the torch Hoses should never be interchanged Nut- used to connect the nipple on the oxygen hose to the torch or regulator, six sides, of the oxygen nut are flat and smooth Right hand threads

Regulator Gauge Readings

After adjusting the pressure on the regulator low-pressure gauge, the torch valve is closed There is a slight rise in pressure on the low-pressure gauge, which is normal The flowing pressure is always lower than the pressure when the torch valve is closed

Name four metals that need especially good ventilation while welding

Anything containing lead Berylliam Zinc Cadmium coated metals

What is the appropriate temperature of a neutral oxyacetylene flame?

5589

Pressure Guage

A low-pressure gauge registers the pressure of the gas flowing to the torch As the pressure increases, it operates the gear and pointer mechanism

Brazing

Brazing is done when two metals, which are not melted, are joined with a third piece that melts at temperatures above 840°F

The welder should stand on one side of the regulator and the gauges when the cylinder is turned on, why?

Burst Regulator

Copper Piping Safety

Copper piping must not be used in the presence of acetylene Copper and acetylene will form copper acetylide This compound is unstable and explodes at the slightest shock

When performing overhead welding, what additional safety equipment should be worn to protect the legs and feet from falling molten metal

Fire resistant work clothes, a cap and a gauntlet gloves. High top shoes and leggings. No cuffs.

Flashback Arrestor

Flashback arrestors are designed to eliminate the possibility of an explosion in the regulator or cylinder A flashback arrestor contains check valves and a stainless steel filter

What is flashback? What must be done immediately if a hissing or squealing noise is heard?

Flashback is when the backfire is not stopped, goes back through the torch and into the hose. Oxygen valve must be turned off first, then the fuel gas torch valve, then inspect the hoses and equipment Put out the flame

Threads Safety

Fuel cylinders are usually fitted with left-hand threads Oxygen cylinder valves are fitted with right-hand threads The thread diameters are also different

Backhand movements

In backhand welding, the torch tip points back toward the weld bead that was created The travel angle for backhand welding is also called the drag angle The tip of the welding torch should be moved slightly as the weld progresses A weaving, oscillating, or circular motion can be used

What are two popular types of welding torches?

Positive pressure (what we use, needs pressure to force into blowpipe) and injection (operate with very low pressure)

Oxygen and Fuel Gas Cylinder

Keep cylinder caps screwed on all cylinders that are not is use Always call oxygen "oxygen"—not air Mark empty cylinders "MT" with chalk

When the welding rod melts down, what procedure should be followed to change the position of your hand on the rod?

Lay the welding rod down with the hot end away from your body, pickup at a new position

What is purpose of the flux?

Material used to prevent, dissolve or help remove oxides and other surface substances

Torch Positions

Moving the torch in the direction that the tip is pointing is called forehand welding The travel angle is the angle between the axis of the torch and a line perpendicular to the weld axis The travel angle for forehand welding can also be called the push angle The work angle is the angle between a line perpendicular to the major workpiece and a plane determined by the centerline of the torch and the weld

Inside corners and t joints

Neither piece of base metal should show any signs of being undercut When making a T-joint in horizontal position, use a forward-inclined, half-moon torch motion Picture

Name the four main parts of a oxyfuel gas welding station?

Outfit, welding table, ventilation, lighting, and other equipment Welding outfit—gas supplies, regulators, hoses, welding torch, goggles, spark lighter

What parts and equipment make up a complete oxyacetylene station?

Outfit, welding table, ventilation, lighting, and other equipment Welding outfit—gas supplies, regulators, hoses, welding torch, goggles, spark lighter

Why must the regulator adjusting screws be turned out until loose before opening the cylinder valves?

Prevents damage to the regulator diaphragm, not so much pressure all at once

Purging

Removing oxygen and water vapor that may be harmful to the welding joint

Soldering

Soldering occurs when two metals, which are not melted, are joined by a third metal that has a melting point below 840°F

What personal precautions must a welder take when welding in overhead welding position?

Sparks, hot metal molten, need to take into account the surface tension and the pull of gravity. Keep metal to the lowest flow temperature as possible

Safety Cap

The cylinder safety cap, which encloses and protects the cylinder, should always be in place when the cylinder is not in use or is being moved

Special precautions are used when attaching the hose to the regulators

The nut used to connect the nipple on the oxygen hose to the torch or regulator has right-hand threads and may be marked OXY The regulator and hose fittings used for acetylene have left-hand threads and may be marked ACE

Torch Tip

Torch tip is determined by the size of the orifice, which controls amount of gas and oxygen to small- not enough gas and oxygen to large- poor welds

What must acetylene cylinders be filled with prior to adding acetylene gas?

Water

Welding tip cleaners

Welding tip cleaners have a series of broaching wires A broach is a tool used to shape a hole

Name at least two things that must be done with cylinders to protect them from accidents or harm

a. Never be dropped or tipped over b. Cylinder cap should always be screwed into place when cylinder s not in use or when it is being moved

Turning On an Outfit and Lighting an Injector-Type Torch

inspect equipment, regulators turn adjusting screws out open oxygen valve turn valve all the way open

Positive Pressure Torch

look at picture

Oxyfuel gas welding

metal working process in which pieces of metal are joined by heating them with a gas flame to their melting point, allowing molten portions to fuse together

Is a regulator opened or closed when the regulator adjusting screw is turned on

open