Weld Report

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Title: Arc Welding and Oxyacetylene Flame Cutting

Introduction of Arc Welding

In electric arc welding, a high temperature arc melts the metal to be jointed while additional

molten metal is being added. After the metal has solidified, the resulting joint will be stronger

than the original metal.

Arc welding is widely used in the manufacturing and construction industries. Special

applications of basic arc welding such as resurfacing steel parts, hard facing, automatic

welding processes, pipe welding and shielded arc welding are widely used.

Information of Arc Welding

The process of arc weldingThe work to be welded is connected to one side of an electric circuit, and a metal electrode is

connected to the other side. These two parts of the circuit are brought together and then

separated slightly. The electric current jumps the gap and causes a continuous spark called an

arc. The high temperature of this arc melts the metal to be welded, forming a molten puddle.

The electrode also melts and adds metal to the puddle. The welding circuit consists of the

work, welding machine, welding cables, electrode holder and electrodes.

The ElectrodeThe electrode usually has a steel core. This core is covered with a coating containing several

elements, some of which burn under the heat of the arc to form a gaseous shield around the

arc. This shield keeps the harmful oxygen and nitrogen in the atmosphere away from the

welding area.

Other elements in the coating melt and form a protective slag over the finished weld.

This slag promotes slower cooling and also protects the finished weld or bead from the

atmosphere. Some coated electrodes are designed with alloying elements in the coating which

change the chemical and physical characteristics of the deposited weld metal. The result of

using properly designed coated electrodes is a weld metal which has the same characteristics

as the work, or base metal, being jointed.


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Electrode classification


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American Welding Society (AWS) Classification NumbersAll AWS numbers consist of three parts. For example E-6010,


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Safety Rules and Regulation:

1. Never wear cloth that could be caught on fire by sparks.2. Do not watch the flames without wearing a safety welding helmet.3. Welding galvanized steel is very dangerous to health because the galvanized clothing

coating on sheet metal has a zinc component where it can caused serious health

problem.

4. Any flux from welding rod is intended to shield a weld from the atmospheric air notshield lungs from atmospheric air.

5. Exercise caution and try to avoid breathing welding fumes.6. Do not touch the work piece with hand in glove after welding the work piece.7. Always use the tong that is provided to take the hot work piece.8. Use all personal protective equipments that are normally used in welding works.

Avoiding Electrical Shock

Electrical shock can kill. To prevent electrical shock:

1. Use well insulated electrode holders and cables.2. The electrode holder, or stinger, should be in good condition with no cracks or missing

insulation.

3. Never leave the welding electrode in the electrode holder, or stinger, when notattending the work.

4. Make sure welding cables are dry and free of grease and oil.5. Keep welding cables away from power supply cables.6. Wear dry hole-free gloves.7. Clothing should also be dry.8. Insulate the welder from the ground by using dry insulation, such as a rubber mat or

dry wood boards.

9. Ground frames of welding units.10.Never change electrodes with bare hands or wet gloves.


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Personal Protective Equipment

Safety gogel protects the eyes from direct heat, light and sparks from work.

The welding helmet protects the head, face and eyes from the effects of the arc during

welding. The filter lens is designed to keep the infrared and ultraviolet light produced by

welding away from eyes.

Welding gloves protect the hands and lower arms from burns and electric shock.

Safety jacket can cover the skin to shield the body from the arc, which is more intense than

sunlight and save clothing from the sparks and spatter of welding.


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Single- Pass Fillet Weld or T-weld

Materials

Two steel plates, E 6013 electrodes.

Tools

Tong, the slag hammer, wire brush, Steel supporter of steel plates.

Procedure

1. Clean the surfaces of the plates with the wire brush.2. Adjust the current on the machine to 90 A and use straight polarity in this project.3. Set up the plates as seen as above figure. Tack welds at the edge of both plates.4. Make the fillet weld in much the same manner as the lap weld was made with the

angle of the electrode is 45 degree triangle.

5. Repeat all the procedures on the other side of the plate.6. Clean completed weld with slag hammer and wire brush and examine the surface.


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Running Continuous Stringer Beads

Materials

Steel plates, E 6013 electrodes.

Procedure

1. Start the machine, check the polarity, and adjust the current for the size of electrodebeing used.

2. Run a continuous stringer bead on the plate, using the full length of the electrodebefore stopping. Make this bead parallel to and about inch from the edge of the

plate.

3. Run additional beads at inch intervals, being sure to keep each bead straight. Checkthe arc length and rate of travel constantly to produce smooth, uniform beads.

4. Continue to make this type of weld until each one is of uniform appearance for itsentire length.

5. Make a bead 2 or 3 inches long and stop the arc. Start the arc again ahead of the crater.Move the electrode back to the crater, using an extra long arc. Bring the rod down

rapidly to the proper arc length and make sure that the new puddle just fuses into the

last ripple of the crater. Proceed with the weld for another 2 or 3 inches and stop.

6. Continue this procedure until there is very little difference in appearance at the pointwhere the arc was restarted. Figure 43-3 shows the right procedure.

7. Try to eliminate the crater at the end of the finished bead by moving back the arc overthe crater and finished bead slowly. As the arc is moved back gradually, increase the

arc length until the crater is filled as in figure 43-5.

8. Try to eliminate the crater by using a very short arc in the crater and pausing untilthere is enough buildup.


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Problems

1. Incomplete penetrationThis type of defect is found in any of three ways:

1) When the weld bead does not penetrate the entire thickness of the base plate.

2) When two opposing weld beads do not interpenetrate.

3) When the weld bead does not penetrate the toe of a fillet weld but only bridges

across it.

Welding current has the greatest effect on penetration. Incomplete penetration is

usually caused by the use of too low a welding current and can be eliminated by

simply increasing the amperage. Other causes canbe the use of too slow a travel speed

and an incorrect torch angle.

Examples of incomplete penetration

2. Lack of fusion cause by travel speed too fast, low amperage, high voltage, excessiveelectrode extension, weld pool too large, position of arc and groove angel.

3. Undercutting is a defect that appears as a groove in the parent metal directly alongthe edges of the weld. It is most common in lap fillet welds, but can also beencountered in fillet and buttjoints. This type of defect is most commonly caused by

improper welding parameters; particularly the travelspeed and arc voltage.

Examples of undercutting

4. Porosity is gas pores found in the solidified weld bead. Pores can occur either underor on the weld surface. The most common causes of porosity are atmosphere

contamination, excessively oxidized work piece surfaces, inadequate deoxidizing

alloys in the wire and the presence of foreign matter. Atmospheric contamination can

be caused by:

Inadequate shielding gas flow. Excessive shielding gas flow. This can cause aspiration of air into the gas stream. Severely clogged gas nozzle or damaged gas supply system (leaking hoses, fittings,

etc.)

An excessive wind in the welding area. This can blow away the gas shield.


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Examples of porosity

Conclusion:

As a conclusion we knew how to joining plate metal using arc welding for T-weld,

tack welds and running continuous stringer beads. We can also see the results of our arc

works and learn to improve our welding skills. The quality of the work is determined by the

bead produced and defects of the welding.

Introduction of Oxyacetylene Flame Cutting

One of the fastest ways of cutting mild steel is by the use of the oxyacetylene torch. Other

advantages of this cutting method are:

A relatively smooth cut is produced. Very thick steel can be cut. The equipment is portable. Underwater cutting is possible with some adaptations. The equipment lends itself to automatic processes in manufacturing.

Information of Oxyacetylene Flame Cutting

The cutting processOxyacetylene flame cutting is actually a burning (rapid oxidation) process in which the

metal to be cut is heated on the surface to the kindling temperature of steel (1600-1800degrees F.). A small stream of pure oxygen is then directed at the work. The oxygen causes

the metal to ignite and burn to produce more heat. This additional heat causes the nearby

metal to burn so that the process is continuous once it has started.

Only those ferrous metals which oxidize rapidly can be flame cut. These metals

include all the straight carbon steels and many of the alloys. Stainless steel and most of the so-

called high speed steels cannot be flame-cut.


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EquipmentCutting is performed with a manual torch. Tips for these torches are interchangeable so that

they can be adapted to cut a wide variety of metal thickness. The torches and tips are

constructed so that they can preheat the work to kindling temperature. The manual torch also

includes a lever for starting and stopping the stream of high-pressure cutting oxygen as

required.

Rules and Regulations:

1. Release the adjusting screw on the regulator before opening the cylinder valve.2. Stand to one side of the regulator before you open the cylinder valve.3. Open the cylinder valve slowly.4. Do not use or compress acetylene in a free state at pressures more than 15 psig.5. Purge your acetylene and oxygen passages individually before lighting the torch.6. Light the acetylene before opening the oxygen on the torch.7. Never use oil or grease on regulators, tips, etc., in contact with oxygen.8. Do not use oxygen as a substitute for air.9. Keep your work area clear of anything that will burn.

Safety Practices:

1. Wear personal protective equipment. Wear welding gloves, helmet, leather apron, weldingchaps, leather shoes, welding goggles, and other personal protective equipment to help

prevent weld burns and injury. Make sure the welding goggles or face shield have at least

a No. 4 filter lens. Do not wear clothing made of synthetic fibers while welding.

2. Fasten cylinders securely. Do not handle cylinders roughly. Chain cylinders in an uprightposition to a wall or cart. When regulators are not on cylinders, keep safety caps in place.Caps will prevent damage to cylinder valves.

3. Open cylinder valves correctly. Open the valve on the acetylene cylinder no more thanthree-fourths of a turn so it can be closed quickly in case of emergency. Open the valve on

the oxygen tank fully. While welding or cutting, leave the valve wrench in position.

4. Keep the tip pointed away from your body. Do not saturate your clothing with oxygen oracetylene. Before and while lighting the flame, keep the tip pointed away from your body.

5. Light the flame with an approved lighter. Using matches to light the torch brings fingerstoo close to the tip.

6. Set the operating pressure carefully. Never use acetylene at a pressure over 15 psi. Followthe manufacturer's recommendations for the correct operating pressures for the metal

being welded and for the tip size being used.


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7. Do not smoke or allow anyone else to smoke near the oxy-fuel gas welder. If fuel gaswere to leak from the unit, smoking could provide ignition and cause a fire or an

explosion.

8. Treat the flame with respect. Keep the flame and heat away from the cylinder, hoses, andpeople. Never lay down a lighted torch. Be sure the flame is out before laying down the

torch. Never walk around with a lighted torch.9. Control flashbacks and backfires. Make certain that reverse flow-check valves and flash

arrestors are installed on the oxygen and acetylene lines.

10. Do not leave the work area until the cylinder valves are closed. Be sure the cylinder valvesare closed and pressure is relieved from the hoses before you leave the work area.

11. Handle hot metal with pliers or tongs. Do not leave hot metal on the welding table becauseunsuspecting persons may touch it and be burned.

Personal Protective Equipment

Safety gogel, welding gloves, safety jacket.

Setting up Equipment and Lighting the Tourch

1) Select the cutting head and attach it to the torch. Position the tip so that the needlevalves are on the side or bottom of the torch when the tip is in the proper welding

position.2) Back off the regulator screws on both units until the screws turn freely.3) Be sure both torch needle valves are turned off (clockwise).4) Open the acetylene cylinder valve to turn. Open the oxygen cylinder valve all the

way.

5) Open the acetylene needle valve one full turn. Turn the adjusting screw on theacetylene regulator clockwise until gas comes from the tip. Light this gas with a

sparklighter.

6) Adjust the regulator screw until there is a gap of about inch between the tip and theflame.

7) Open the oxygen needle valve on the torch one full turn. Turn the oxygen regulatoradjusting screw clockwise until the flame changes.

8) Continue to turn the adjusting screw until produces a neutral flame.


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Straight Line Cutting

Materials

Steel bar, cutting tip.

Procedure

1) Draw series of straigh lines on the steel bar.2) Light and adjust the preheating flame to neutral.3) Start cut by holding the tip over the edge of the metal in 90 degree position.4) When the edge becomes bright red, turn the cutting oxygen on with the lever. Then,

turn down the tip 5 degree following the way of the cutting along the process.

5) Continue the cut, making sure that the tip is square with the work.6) Observe that when the rate of travel is right, the slag or iron oxide coming from the cut.7) Finish the cut and check the flame-cut edge for smoothness, straightness and amount

of slag on the bottom edge of the cut surfaces.


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Problem

Conclusion

Oxyacetylene flame cutting process is applying the process of fast oxidation to cut the steel

plates. This process needs a cutting torch with a lever for controlling the stream of high

pressure cutting oxygen. The quality of the work is determined by the smoothness,

straightness and amount of slag on the bottom edge of the cut surfaces.

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