Welding Equipment & Safety Manual

Transcription

1 Welding Equipment & Safety Manual Oxygen / Acetylene Gas Welding Electric Arc Welding Metal Inert Gas (M.I.G) Welding Tungsten Inert Gas (T.I.G) Welding

2 GENERAL SAFETY GUIDELINES : WELDING SHOP Welding poses a fire hazard. All welding processes are restricted to the outdoor sculpture welding area. Open flames, welding sparks and welding fumes are prohibited inside the building. Do not allow water or moisture to come in contact with electrical welding leads, extension cords or metal. Do not stand in water or puddles while welding. Students must comply with all safety directions and instruction provided by the instructor. Welding can be a dangerous activity if done in an unsafe manner. Use equipment in a safe and correct manner. Some welding materials are explosive and can be unstable if not used properly. Use the appropriate safety protection as directed for each welding process. This includes necessary goggles, helmets, gloves or protective clothing. Avoid wearing worn or frayed clothing that could catch fire easily. Do not wear synthetic materials. Be aware of all emergency fire procedures. This includes the location of emergency phones, fire alarms, fire extinguishers and first aid kits. This manual is for reference purposes. Specific safety and operational procedures will be presented during course demonstrations. The instructor reserves the right to restrict student use of the welding area and equipment due to reckless or inappropriate actions. If you are pregnant or suffer from asthma please inform the instructor immediately. Pregnant women are restricted from using the welding area. Asthma suffers should invest in respiratory protection to protect against certain fumes.

3 OXYGEN / ACETYLENE GAS WELDING: EQUIPMENT, PROCEEDURES & SAFETY The TORCH HANDLE allows gas and oxygen to mix and adjust for the proper welding flames. The control valves correspond to the colored hoses attached: RED = Acetylene, GREEN = Oxygen Valve control flow: On/Open = counter-clockwise (left) Off/Close = clockwise (right) DO NOT OVER-TIGHTEN VALVES WHEN CLOSING STOPPING GAS FLOW! The CUTTING HEAD splits the oxygen pressure supply into a pre-heat flame and cutting flame. When the cutting lever is depressed, the higher pressure oxygen flame pushes the metal material out of the way. Generally, the control valve on the torch body is left on & the cutting torch oxygen valve is used for adjustments. Each gas has its own regulator & should not be switched! The high-pressure gauge measures the PSI (Pounds Per Sq. Inch) within the gas cylinder tank. The low pressure gauge measures the PSI allowed through the hoses leading to the torch. The adjusting screw regulates the pressure between the high & low gauges. CLOCKWISE (IN) = INCREASE PSI COUNTER CLOCKWISE (OUT) = DECREASE PSI NEVER OPEN A GAS CYLINDER WITH A REGULATOR ADJUSTMENT SCREW SPUN IN! THE SCREW SHOULD BE LOOSE COUNTER CLOCKWISE

4 OXYGEN / ACETYLENE GAS WELDING: EQUIPMENT, PROCEEDURES & SAFETY SYSTEM ON : Starting to weld 1. Make sure all on/off valve controls are closed and that the REGULATOR ADJUSTMENT SCREW is loose & spun out (counter clockwise). Both pressure gauges should read zero ( 0 ) PSI. 2. Slowly open the main valve control located on the top of the gas cylinders. COUNTER CLOCKWISE (left) = OPEN The tank is on when the high pressure gauge needle measures a PSI reading. WARNING 3. Set the low pressure gauge by turning in (clockwise) the regulator adjustment screw until the appropriate PSI is registered by the low pressure needle gauge. (this will be the numbers on the INNER circle = PSI). See table below for PSI settings. DO NOT EXCEED 15 PSI for the ACETYLENE GAS!! Gas is now supplied to the torch handle 4. Select and attach the welding tip to the torch if you haven t already done so. Screw the tip on the torch until it is hand tight. 5. Proceed to light the torch & set the welding flame

5 OXYGEN / ACETYLENE GAS WELDING: EQUIPMENT, PROCEEDURES & SAFETY SYSTEM ON: LIGHTING THE TORCH & SETTING THE WELDING FLAME 1. With the proper PSI set, open the ACETYLENE gas valve a 1/4 1/2 turn (you can hold the end of the welding nozzle next to your ear, but not pointing toward your head, and you should be able to hear the gas coming from the nozzle). Do not open the acetylene gas valve completely open at any time. 2. Ignite the gas at the end of the welding tip using the FLINT STRIKER. DO NOT USE A HAND HELD LIGHTER! Increase the acetylene gas volume (flame) until the black carbon smoke disappears. 3. Introduce the OXYGEN into the gas slowly until a neutral flame is achieved = distinct bright blue cone at the welding tip. A neutral flame is the ideal mixture/ratio of gases to produce the hottest & most efficient flame possible for welding steel. Various adjustments can be made to the overall volume of gases to achieve the best welding flame for a particular thickness of metal. Any adjustment should still result in a neutral flame. SYSTEM OFF: TURNING THE TORCH OFF / SHUTTING THE TANKS DOWN: 1. Turn the torch flame off by closing the OXYGEN torch control valve 1 st, then the ACETYLENE 2 nd If you are finished welding for the day, the tanks need to be shut down 2. Close the MAIN CYLINDER VAVLES on the tanks. 3. Open the control valves on the torch handle to release to gases trapped in the hose lines. Keep the valves open until both regulator gauges on each tank reach zero PSI (bleeding the lines). Then close these valves on the handle. 4. Spin the regulator adjustment screws OUT (counter clockwise) until they are loose DO NOT UN-SCREW THEM COMPLETELY OUT OF THE REGULATOR!!! (you should see 3/4 1 of threads). 5. Remove the welding tip or cutting attachment from the torch; wrap the lines around the tank & off the floor. DO NOT LEAVE THE TANKS OPEN AND UNATTENDED IN THE STUDIO

6 OXYGEN / ACETYLENE GAS WELDING: EQUIPMENT, PROCEEDURES & SAFETY BEGINNING TO WELD: Ideally, the metal to be welded should be free of rust, scale, oil, enamel & paint. These items contaminate the weld & produce toxic fumes. Any joints that are to be gas welded should be prepared by grinding the edges clean or beveling the joint intersection to maximize the welded surface tension & penetration. Metal less than 1/8 thick do not need to be beveled at the joints. Start any gas weld by PRE-HEATING the joint evenly in a small circular rotation until a bright orange heat is achieved in both pieces of metal. Once the mild steel reaches its melting point (about 3300F), it will quickly become molten and appear shiny and watery. The melting of the steel together will connect them, however, a welded joint relies on surface mass or tension. A FILLER ROD (3/16 or 1/8 - also called a welding rod) is introduced to apply more steel material into the weld. Continuing a circular rotation- melt both pieces of steel and add the filler rod as needed as you move across the joint at a steady speed. If you move too slowly, you may melt the steel to the point that it drops-through creating a hole. If you move too fast, you will not get any penetration in the weld, the filler rod will lay on top of the steel and your joint will be very weak (and ugly). Getting used to the speed, in relationship to the metal thickness is the most difficult part of gas welding. Thinner metals will seem to melt too quickly, while thicker metals may seem to take a long time to weld. Generally, there are some metal that are just too thin or thick to gas weld & a different welding system or connection device should be used. ***CAUTION: During the welding process it is possible for the tip to OVERHEAT. You may also encounter weld explosions (the metal puddle traps excess oxygen & impurities) that POP and send liquid metal flying! Both of these situations may cause a FLASHBACK or BACKFIRE at the nozzle tip. IF the flame goes OUT after a FLASHBACK & you hear a LOUD SQUEELING noise coming from the torch = IMMEDIATELY TURN OFF THE OXYGEN & ACETYLENE TORCH CONTROLS! The welding flame has combusted INSIDE the torch nozzle & is still burning! This can be very destructive to the equipment & create an unsafe situation.

7 OXYGEN / ACETYLENE GAS WELDING: EQUIPMENT, PROCEEDURES & SAFETY CUTTING TORCH ATTACHMENT: Using the cutting attachment requires an adjustment to the PSI pressure settings on the regulators. Generally, the oxygen pressure setting is increased see below for recommended pressure settings. A good regulator set-up for most metals would be PSI oxygen / 3-5 PSI acetylene. The main oxygen control valve is used on the cutting attachment open the torch valve control and leave it on. Lighting the torch is the same as using a welding tip : open acetylene 1/2 turn, light gas with striker, introduce oxygen slowly until a neutral flame is achieved. NOTE: the cutting tip has 6 small cones (instead of one) with a larger hole in the center of the six that is not engaged until the cutting lever is depressed. Pre-heat the metal to be cut until a dull red color is achieved, then depressed the cutting lever a burst of high pressure oxygen super-heats the metal and essentially blows the material out of the way.

8 OXYGEN / ACETYLENE GAS WELDING: EQUIPMENT, PROCEEDURES & SAFETY SAFETY GUIDELINES : GAS WELDING CLOTHING 1. ALWAYS WEAR GLOVES & GAS WELDING GOGGLES OR WELDING SHADE WHILE USING A TORCH 2. CLOSED TOE SHOES ARE REQUIRED LEATHER BOOTS OR SHOES ARE PREFERRABLE 3. WEAR NATURAL FIBERS (COTTON) SYNTHETICS CAN BE FLAMMABLE OR MELT 4. USE AVAILABLE SAFETY APRONS OR LEATHER PROTECTION 5. A WELDING CAP OR BASEBALL CAP IS RECOMMENDED TO PRETECT YOUR HAIR TIE BACK LONG HAIR REGARDLESS WORK AREA 1. NEVER POINT TORCH HEAD AT TANKS, HOSE LINES OR PEOPLE 2. KEEP GAS LINES FROM UNDERNEATH WORKING AREA-KEEP THEM BEHIND YOU 3. KEEP TANK CART AT LEAST 6 FT. AWAY FROM WORKING AREA 4. BE SURE THAT TANKS ARE SECURED WITH RETENTION CHAIN BEFORE MOVING THE TANK CARTS 5. DO NOT LEAVE TORCH BURNING UNATTENDED 6. DO NOT PLACE TORCH OR HOSE LINES ON TOP OF HOT WORKING SURFACES 7. SHUT DOWN TANKS WHEN YOU ARE FINISHED AND WRAP LINES UP OFF THE FLOOR 8. BE AWARE OF OTHERS WORKING AROUND YOU EMERGENCY 1. IN CASE OF EMERGENCY NOTIFY THE INSTRUCTOR IMMEDIATELY OR CALL OUPD BE AWARE OF THE LOCATIONS OF FIRE EXTINGUISHERS IN THE STUDIO 3. NOTIFY THE INSTRUCTOR OF ANY SEVERE BURNS OR INJURIES IMMEDIATELY 4. IN CASE OF EXTREME EMERGENCY ALERT EVERYONE IN THE STUDIO, PULL THE FIRE ALARM & EVACUATE THE BUILDNIG ADDITIONALLY- PLEASE FOLLOW THE GENERAL STUDIO SAFETY GUIDELINES POSTED IN THE STUDIO

9 ELECTRIC ARC WELDING: EQUIPMENT, PROCEEDURES & SAFETY ELECTRIC ARC / ELECTRODE WELDING BASICS: The arc process welds using electricity instead of gases. High amperage current creates an electric arc at the end of a flux-coated steel electrode that can reach 9000 F instantly. As the base metal melts, the electrode builds the weld much like the filler rod in gas welding. The arc process is generally the strongest (structurally), but the most difficult to learn & generally the least aesthetic. AC/DC (+), (-) polarity indicates the current (direction) of the electricity. Current polarity effects the manner in which some metals melt. Most electrodes are produced specifically to work most efficiently in a certain polarity. DC+(reverse) & AC (alternating) are the most common polarity settings for welding most metals. DC- (straight) is used for special applications, inverted welding and deep penetration welds. AMPERAGE control is the secondary setting for most arc welders. Depending on the model, an amperage selection range of amps is used to adjust the intensity of the current depending on the thickness of the metal being welded and the thickness of the electrode. This variable is usually figured out through trial and error; as every welder current is different. For the most part, an AMP setting between will work for most metals 3/32 5/8 thick with a 3/32 or thicker electrode. ELECTRODES come in various compositions & thicknesses. A number is placed on rods to identify the type of metal, flux and the reaction with particular currents. E6011, E6013 & E7018 are the most common steel rods available in 1/16, 3/32 & 1/8 thick. ROD PROPERTIES E-6010 easy to use, very little weld splatter E-6011 easy to use, spatters a lot E-6013 easy to use, little spatter, decent weld bead E-7018 harder to use, beautiful weld result on clean metal

10 ELECTRIC ARC WELDING: EQUIPMENT, PROCEEDURES & SAFETY WELDING with electrodes can be difficult at first. In order to start-- an arc must be struck by completing the circuit at the end of the electrode. The GROUND CLAMP must be in contact with the metals being welded to complete the circuit. Once the arc begins, the electrode must be kept close enough the base metal to sustain the arc without touching the base metal. Generally, the electrode should be kept 1/16 1/8 above the weld. A common problem with electrodes is that they can stick to the metal being welded easily if they make contact. It takes patience and practice to get the feel for arc welding. As the arc strikes, the welding procedure is basically the same as gas. A small circular motion across the metal joint is used as you move in a direction over the weld. Unlike gas, the travel (or weld) speed is SUBSTANIALLY faster and far more tricky to establish. Most beginners tend to go too fast or too slow which results in weak & sloppy welds. THE GROUND CLAMP WILL TRANSFER THROUGH ALL METAL INCLUDING THE STEEL WORKTABLE. DO NOT PLACE THE ELECTRODE HANDLE ON THE WORKTABLE IT WILL CAUSE AN ARC! GENTLY SET THE HANDLE ON THE FLOOR OR ON ANOTHER SURFACE WHILE THE WELDER IS ON. SAFETY WARNING: THE ELECTRODE ARC PRODUCES A HIGH INTENSITY ULTRA-VIOLET LIGHT THAT CAN CAUSE DAMAGE TO THE EYES AND SKIN. DO NOT LOOK DIRECTLY AT A WELDING ARC WITHOUT A FULL FACE WELDING HELMET! EXPOSED SKIN WILL BE SUBJECT TO SUN-BURN! 1. Welding a helmet, gloves and available protective clothing 2. Wear natural fibers & closed toe shoes (leather or boots preferable) 3. A long sleeve shirt should be used to protect arms from getting burned 4. Arc produces a lot of fumes that can be toxic in high concentrations a particle & welding fume respirator should be worn 5. Always place welding screens in front of & around the work area to protect others in the studio 6. Wrap leads up and off the floor when you are finished

11 METAL INERT GAS (MIG) WELDING: EQUIPMENT, PROCEEDURES & SAFETY MIG welding is an electric process that includes a shielding gas (flux). The filler rod/electrode is a wire that feeds out of a gun. The wire is encased on a spool within the welder and fed through a line to the trigger MIG gun (+). When the wire makes contact with the base metal an arc is struck immediately. As the wire & base metal melt, the continuous wire feed builds up the weld. VOLTAGE & WIRE SPEED CONTROLS: The MIG welder controls adjust for the volts (amperage) & the speed of the wire being fed. The settings are based on the thickness of the metal being welded & the thickness of the wire spool. Generally, the higher the voltage, the faster the wire speed the wire will melt quicker at higher voltage. For most welding of thinner metals, voltage range settings between w/ wire speeds of are usually sufficient. Testing the setting is usually necessary to dial-in the controls when you weld you should hear a constant, smooth sizzling sound. Improper settings or technique results in a sputtering sound. SHEILDING GAS: Carbon Dioxide, Argon, Helium or a mixture is used as a flux with the MIG. The type of gas used is dependent on the type of metal being welded. Be sure that the main gas valve on the cylinder is turned on before welding. DO NOT TOUCH or adjust the regulator!! It is preset to the appropriate pressure & remains constant throughout the process. The shielding gas will emit through the gun tip while the trigger is depressed and wire is being fed. MIG welding involves a circular motion that sweeps across the weld and shoots the wire into the gap being filled. As the arc is struck, the welding tip should be kept 1/8 off the surface of the base metals. If the tip is too close, the welding spatter may clog or seal off the wire at the tip. If the tip is too far away, the circuit may not connect efficiently and a rough sputtering will occur. A novice welder generally tends to hold the MIG tip too far away. The weld travel speed, like the ARC, is a major factor in the aesthetic & structure of the weld. THE TRIGGER IS LIVE WHILE THE WELDER IS ON THE TIP IS NOT LIVE. BE CAREFUL NOT TO SET THE MIG GUN DOWN WHERE THE TRIGGER MAY ENGAGE THE WIRE WILL FEED CONTINUOUSLY UNTIL THE TRIGGER IS RELEASED!! SAFETY WARNING: THE MIG ARC CREATES AN INTENSE ULTRA-VIOLET LIGHT! A FULL FACE WELDING HELMET, GLOVES AND PROTECTIVE CLOTHING MUST BE WORN. ADHERE TO PREVIOUS ARC WELDING SAFETY GUIDELINES

12 TUNGSTEN INERT GAS (TIG) WELDING: EQUIPMENT, PROCEEDURES & SAFETY THE ONLY ADJUSTMENTS MADE ON THE WELDER ARE THE CENTER AMPERAGE CONTROL & THE POLARITY SELECTOR!! DO NOT SWITCH OR CHANGE ANY OTHER SETTINGS ON THE TIG WELDER!!! AMPERAGE / VOLTAGE CONTROL POLARITY ADJUSTMENT TIG welding is very similar to oxy/acetylene gas welding. A torch is used in conjunction with a filler rod, however the TIG process is an electrical welding procedure. The arc is struck at the end of a tungsten electrode where the base melts instantly within a inert shielding gas atmosphere (flux). The arc is induced by a hand control on the torch itself and allows for variable voltage control or arc intensity. POLARITY: For most metals the welding polarity should be set in DCSP, STRAIGHT POLARITY (DC-). This includes steel, bronze, stainless steel, copper, and titanium. For welding aluminum the polarity should be set to AC. TUNGSTEN ELECTRODE & AMPERAGE RANGE: The table below outlines the usable amperage range for specific tungsten sizes. Using excessive amperages will melt the tungsten electrode. THICKER METALS REQUIRE THICKER ELECTRODES / THINNER METALS REQUIRE THINNER ELECTRODES 3/32 & 1/8 electrodes will handle a moderate range of metal thicknesses. 2% Thorariated electrodes (red) are generally used for DC- welding, Pure Tungsten (green) are preferable for AC welding.

13 SHEILDING GAS: ARGON is preferred for all applications with the TIG welder. The argon atmosphere provides maximum shielding from contaminants entering the weld and exhibits excellent flow properties in the molten metals. DO NOT TOUCH or adjust the regulator!! It is preset to the appropriate pressure & remains constant throughout the process. The shielding gas will emit through the torch tip while the arc is struck and continue for approximately seconds after the hand control switch is turned off. TORCH HANDLE: The torch handle consists of 4 major components. 1) tungsten electrode contained within the torch 2) the ceramic cup or nozzle that directs the flow of the argon 3) the rear locking / adjusting handle allows tungsten length variation 4) the remote hand control to turn the current on & adjust. THE TIG WELDER IS A VERY DELICATE PIECE OF EQUIPMENT. MIS-USE OR ABUSE WILL NOT BE TOLERATED. STUDENTS WILL BE EXPECTED TO TAKE GREAT CARE OF THE UNIT & PARTS DURING OPERATION. ONLY THOSE STUDENTS DEMONSTRATING ACCEPTABLE GAS WELDING SKILLS WILL BE ALLOWED TO USE THE TIG WELDER. USE OF THE TIG WELDER WILL BE RESTRICTED TO CLASS MEETING TIMES OR UNDER DIRECT SUPERVISION BY THE INSTRUCTOR OUTSIDE OF CLASS. SAFETY WARNING: THE TIG ARC CREATES AN INTENSE ULTRA-VIOLET LIGHT! A FULL FACE WELDING HELMET, GLOVES AND PROTECTIVE CLOTHING MUST BE WORN. ADHERE TO PREVIOUS ARC WELDING SAFETY GUIDELINES

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