gas welding

basic information of processes gas welding

1. SUBMITTED BY: MOHIT NAVRIYA (K10778) B.TECH EE 6 TH SEM Gas Welding SUBMITTED TO: MR.ADITYA MISHRA (ASST. PROFESSOR OF ME DEP.)

2. Welding is a materials joining process which produces coalescence of materials by heating them to suitable temperatures with or without the application of pressure or by the application of pressure alone, and with or without the use of filler material. Welding is used for making permanent joints. . WELDING

3. TYPES Plastic Welding or Pressure Welding The piece of metal to be joined are heated to a plastic state and forced together by external pressure (Ex) Resistance welding Fusion Welding or Non-Pressure Welding The material at the joint is heated to a molten state and allowed to solidify (Ex) Gas welding, Arc welding

4. Classification of welding processes : (i ). Arc welding Carbon arc Metal arc Metal inert gas Tungsten inert gas Plasma arc Submerged arc Electro-slag (ii). Gas Welding Oxy-acetylene Air-acetylene Oxy-hydrogen (iii). Resistance Welding Butt Spot Seam Projection Percussion (iv)Thermit Welding (v)Solid State Welding Friction Ultrasonic Diffusion Explosive (vi)Newer Welding Electron-beam Laser (vii)Related Process Oxy-acetylene cutting Arc cutting Hard facing Brazing Soldering

5. GAS Welding INTRODUCTION Definition: Join metal by heating surfaces to be joined to melting point with gas flame Fusing metal into homogeneous mass Letting it solidify into a single unit Flame in cone reaches temperatures as high as 5800 º to 6300ºF Filler rod may or may not be used to intermix with molten pool

6. welding process is used for both fabrication and construction, maintenance and repair We Still used this for brazing, soldering, welding metals with low melting points; general maintenance and repair work Early Egyptians, Greeks, and Romans used alcohol or oil flame to fuse metals

7. GAS WELDING EQUIPMENT... 1. Gas Cylinders Pressure Oxygen – 125 kg/cm2 Acetylene – 16 kg/cm2 2. Regulators Working pressure of oxygen 1 kg/cm2 Working pressure of acetylene 0.15 kg/cm2 Working pressure varies depends upon the thickness of the work pieces welded. 3. Pressure Gauges 4. Hoses 5. Welding torch 6. Check valve 7. Non return valve

8. Oxy-Acetylene welding

9. Types of flame

10. Carburising Neutral Oxidising The Oxy-acetylene welding Flame

11. Gases used Oxygen extracted from air and compressed into cylinders at high pressure. Cylinder is black. Oil should never be brought into contact and should not be used on fittings Acetylene (C 2 H 2 ) is a fuel gas. Cannot be compressed directly as explodes at high pressures. Cylinders are packed with porous material which is filled with acetone. Acetone absorbs acetylene. Cylinder colour coded maroon

12. Gas Pressure Regulators One gauge indicates the pressure of the cylinder and the other indicates the pressure in the supply pipe to the torch.

13. Welding torch Oxygen and acetylene are delivered to the torch by separate hoses. Each gas is controlled by a valve on the torch. The two gases mix in the torch and after they are ignited burn at the nozzle. Mixer Needle valves

14. Flashback Arrestors These are positioned on both the fuel gas and oxygen supply between the hose and the regulator. Their purpose is to prevent the return of a flame through the hose into the regulator.

15. Filler Rods and fluxes Filler rods are used when additional filler metal is required in the weld area they come in different diameters. Fluxes protect the weld pool from contamination by oxygen and nitrogen, they are normally in paste form placed on a heated filler rod before welding begins

16. GAS CUTTING … Automatic Gas Cutting Manual Gas Cutting

17. Application It is used in the manufacture of automobile bodies, aircraft frames, railway wagons, machine frames, structural works, tanks, furniture, boilers, general repair work and ship building.

18. Thank you ..!!