Page 68 - CITS - Welder - Trade Theory

WELDER - CITS

MODULE 3 : Weldability of metals (OAW, SMAW)

Lesson 14-26 : Common Gases used for Gas welding

Objectives

Objectives:At the end of this lesson you shall be able to
• name the different types of gases used for welding and cutting
• compare the different types of gas flame combinations.

Introduction:
In welding and cutting processes, gases play crucial roles in providing heat, protection. & control, oxy-acetylene
flame is widely used on oxy-fuel welding & cutting.
The flame produced by mixing a flammable gas and oxygen in the nozzle or tip of the blow pipe is called flame.
In the gas welding process, the welding heat is obtained from the combustion of fuel gases in the presence of a
supporter of combustion (oxygen).
(Oxy-acetylene gas flame combination is used in most gas welding processes because of the high temperature
and heat intensity)

Types of Gases Used In Welding & Cutting
Comparison of different gas flame combinations and their use

Sl. Fuel gas Supporter Name of the gas Temperature Application/uses
No. Of combustion flame

1 Acetylene Oxygen Oxy- 31oo to 3300°c To weld all ferrous and non
acetylene flame (Highest ferrous metals and their alloys;
temperature) gas cutting & gouging of steel;
brazing bronze welding; metal
spraying and hard facing.
2 Hydrogen Oxygen Oxy- 2400 to 2100°c Only used for brazing, silver
hydrogen flame (Medium soldering and under water gas
temperature) cutting of steel.
3 Coal gas Oxygen Oxy-coal gas flame 1800 to 2200°c Used for silver soldering
(Low underwater gas cutting of steel.
temperature)
4 Liquid Oxygen Oxy- 2700 to 2800° Used for gas cutting steel
petroleum liquid petroleum C (Medium heating purposes.(Has moisture
gas(LPG) gas flame temperature) and carbon effect in the flame.)
5 Acetylene Air Air-acetylene flame 1825 to1875°C Used only for soldering, brazing,
(Low heating purposes and lead
temperature) burning.

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