SUBMITTED BY: MOHIT NAVRIYA (K10778)B.TECH EE 6TH SEM

Gas Welding

SUBMITTED TO:MR.ADITYA MISHRA(ASST. PROFESSOR OF ME DEP.)

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

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

WeldingThe material at the joint is heated to a molten state

and allowed to solidify(Ex) Gas welding, Arc welding

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

FrictionUltrasonicDiffusionExplosive

(vi)Newer WeldingElectron-beamLaser

(vii)Related ProcessOxy-acetylene cuttingArc cuttingHard facingBrazingSoldering

GAS WeldingINTRODUCTION 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 5800º to 6300ºF

Filler rod may or may not be used to intermix with molten pool

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

GAS WELDING EQUIPMENT...1. Gas Cylinders

PressureOxygen – 125 kg/cm2Acetylene – 16 kg/cm2

2. RegulatorsWorking pressure of oxygen 1 kg/cm2Working pressure of acetylene 0.15 kg/cm2 Working pressure varies depends upon the

thickness of the work pieces welded.3. Pressure Gauges4. Hoses5. Welding torch 6. Check valve7. Non return valve

Oxy-Acetylene welding

Types of flame

Carburising Neutral Oxidising

The Oxy-acetylene welding Flame

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 (C2H2) 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

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

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

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.

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

GAS CUTTING…

Automatic Gas Cutting

Manual Gas Cutting

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.

Thank you ..!!