welding & gas cutting.pptx for hot work safety related isssies

Ppt

1. Welding & Gas cutting safety

2. GENERAL SET UP

3. TERMS USED IN WELDING & CUTTING OPERATION Back fire : The momentary recession of the flame into the torch tip followed by immediate reappearance of the flame. Flash Back : A recession of the flame into or back of the mixing chamber of the torch. 3) Cover glass: Clear glass used in goggles,hand shields & welders screen to protect the filter glass from the spatters.

4. GAS CUTTING TORCH This is device used in gas cutting for controlling the gases used for preheating & the oxygen for cutting the metal.

5. TERMS USED IN WELDING & GAS CUTTING WELDING ELECTRODE : Filler metal in the form of wire or rod,bare or covered,through which current is conducted between electrode holder & arc. FLASH BACK ARRESTER : It is device to stop the recession of the flame into or back of the mixing chamber.

6. TERMS USED IN WELDING & GAS CUTTING ELECTRODE HOLDER: A device used for mechanically holding the electrode & conducting current to it. MIXING CHAMBER : That part of welding or cutting torch wherein the gases are mixed for combustion

7. HAZARDS IN WELDING & CUTTING Radiation hazards Hazard due to dangerous fumes & gases. Burns & eye injuries. Fire & explosion hazards. Environment /atmospheric hazards Electric shock Postural fatigue Hazards associated with working at height High noise level in certain operations

8. SAFETY IN ARC WELDING ELECTRIC SHOCK: The electrode & work ( ground ) are electrically HOT while operation is ON. Do not touch hot parts with bare or wet skin,use dry & hole free gloves. Maintain the electrode holder,work clamp,welding cable & welding machine in good ,safe operating condition. Never dip electrode in water for cooling. When you are working above floor level,protect yourself for fall if you get shock. Never wrap the electrode cable around any part of your body.

9. SAFETY IN ARC WELDING 2) ARC BURN IS MORE SEVERE THAN SUN BURN : Use proper filter & cover glass to protect your eyes. Use suitable full body clothing to protect your & that of your helpers skin from the arc rays. Give safety instructions to nearby personnel not to watch or exposed to harmful rays. 3) Falling droplets of molten slag & metal arc will result in fire hazard, cover the rest area with suitable shielding or asbestos sheet. Always use oil free protective wear ,ear muffs while welding in out of position or confined space. 5) When not welding,make sure that no part of electrode circuit is touching work or ground,it may cause overheating & create fire.

10. SAFETY IN ARC WELDING 6) Be sure that the work cable is connected to the work as close to the welding area as practical. 7) Welding fumes & gases are hazardous to health, wear suitable mask or breathing apparatus , maintain proper ventilation to avoid accumulation harmful gases. 8) Before doing any repair in gas cylinder /container, make sure that the cylinder is cleaned & purged by Nitrogen or inert gas. 9) Installation, troubleshooting & maintenance work is to be done always by qualified electrician. 10) Frames of welding equipment & power source are grounded properly & there must be good earthing . 11) Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease), a minimum distance of 20 feet (6.1 m) or by a noncombustible barrier at least 5 feet (1.5 m) high having a fire-resistance rating of at least one-half hour.

11. SAFETY IN ARC WELDING Turn OFF before doing any maintenance work inside the welding equipment. Never change electrode with bare hands, wet gloves or standing on wet floors. 13) Worn out work lead or electric leads exposing bare conductor should be covered with rubber,plastic or plastic tape. Take care to keep welding cables away from power supply cables or high tension cables. 15) Use only 24 volts electrical apparatus when working in confined space. 16) Ground the work piece separately from the welding return connection. 17) While using welding rectifier or generator,ensure that welding cable lugs are properly crimped & terminated so that there is no loose connection,which will cause insulation to burn.

12. HAZARDS OF COMPRESSED GASES PRESSURE HAZARD: hazard due to equipment failure & leakage from system . Improper pressure control may cause unsafe reaction rates . 2 ) DIFFUSIVITY : Diffusion of leaking gas cause rapid contamination of atmosphere,toxicity,anesthetic effects & rapid formation of explosive concentration of flammable gases. 3 ) FLASH POINT: The flash point of gas under pressure will always lower than ambient room temperature & leaking gas will rapidly form the explosive mixture with air.

13. GENERAL CYLINDER SET UP

14. ACETYLENE CYLINDER It is welded steel tube. It is filled with spongy material. The spongy material is saturated with chemical solvent called ACETONE Acetylene gas is absorbed in acetone. Safety fuse plugs melts at 220° F Visual inspection, hydrotesting to be done before filling gas. Acetylene is UNSTABLE under pressure greater than 15 psi Normal pressure in cylinder 220 lb/in²

15. ACETYLENE CYLINDER

16. OXYGEN CYLINDER ( GAS FORM ) It is in gas form. Safety fuse plug & disc allows oxygen to escape if the cylinder is subjected to heat & the pressure begins to rise. Oxygen is colourless,odorless & tasteless gas. It is slightly higher than air. Most common size of cylinder is 244 cu. Ft of oxygen. Pressure 2200 lb/in² at 70 ° F

17. SAFE PRACTICES CYLINDER & EQUIPMENTS : Fasten cylinders to be used in an upright position. Keep clear space between cylinders & the work. ‘CRACK’ the cylinder valve before starting the work after some period. Always attach regulators to gas supply. Never force connections that do not fit properly. Use hoses that are specially made for oxygen-fuel gas equipments. ALWAYS use FLASH BACK ARRESTER. Green oxygen hose has RIGHT HAND thread nut & red fuel gas hose has LEFT hand thread nut. Before opening cylinder valve ,pressure regulating adjusting screw must released by rotating anticlockwise until it turns freely. While opening cylinder valve, stand to one side of the regulator. Always make sure that there is enough oxygen –fuel gas available in cylinder to complete your work.

18. SAFE PRACTICES Check all connections & joints for leakage. Never tighten leaky connection between regulator & cylinder when under pressure. Attach proper welding tip or cutting nozzle & use correct pressure. Always use FRICTION LIGHTER for lighting torches. If the flame goes out & burns back within the torch,producing hissing noise ,IMMEDIATELY shut off the torch or flame will burn through torch & may cause injury. Do not relight flames on hot work. After finishing days work, close the cylinder valve. Open torch valve to release all pressure from hose & regulator. When the gauge pressure drops to zero,turn out the pressuer adjusting screw in anticlockwise direction. This will prevent the release of gas & possible accident if anybody moves the regulator when the cylinder valve is open.

19. SAFE PRACTICES 2 ) FIRE PREVENTION : Never weld or cut near potential hazards. Ensure that persons involved in welding or cutting operation is familiar with precautions to betaken to prevent fire. Always maintain safe work place. Provide fire barriers. Provide fire extinguishing equipments. Consider need for fire watcher. Inspect the work area after completing operation. Before starting work always inspect work location & surrounding area. Always inform supervisor or concern person about the location of work

20. SAFE PRACTICES 3 ) PREVENTION WITH OXYGEN : Keep regulators, hoses & other oxy-fuel gas equipment free of grease,oil & other combustibles. Never use lubricants on oxy-fuel gas equipments. Never substitute oxygen for compressed air. Never allow oxygen or oxygen rich air to saturate your clothings . NOTE: OXYGEN CAUSE FIRE TO BURN MORE RAPIDLY. ANYTHING THAT BURNS IN AIR BURNS VIOLENTLY IN OXYGEN.

21. SAFE PRACTICES 4 ) PRECAUTIONS WITH FUEL GASES : Make sure confines space is well ventilated before entering. Do not bring gas cylinders in confined space. Do not leave gas cylinders in confined space when not in use. Know basic concepts about gases . Never release fuel gases where it might cause fire or explosion. Never use fuel gases above its rated pressure range . NOTE: FUEL GAS CAN CAUSE RAPID SUFFOCATION WITHOUT WARNING

22. SAFE PRACTICES

23. UNSAFE PRACTICES

24. LEAK DETECTION & REMEDIES LEAK SURROUNDING THE VALVE STEM : If leak is found around the stem when valve is open,tightened the gland nut. If leak not attend by this discontinue the use of this cylinder , tag the cylinder & place it outdoor. LEAK FROM THE CYLINDER VALVE : If cylinder leaks from the cylinder valve,it can not be shut off ,take cylinder out door & tag it defective & call supplier.proper warning signs to be placed. 3) LEAK AT FUSIBLE PLUG : If leak develops near fusible plug,move cylinder out door,place it away from any ignition source.open the cylinder valve slightly & allow acetylene to escape. NOTE: IN CASE OF WELDING OR GAS CUTTING THE LEAKS MUST BE DETECTED ONLY BY SOAP SOLUTION .

25. THANK YOU