Types Of Flames - Weebly



Types of Flame

Introduction to Flame

Flame is mostly found in Gas Welding type mainly in Oxy-Acetylene Welding (OAW).

Oxy-Acetylene Welding (OAW): It is a type of gas welding in which coalescence Is produced by heat obtained from burning a mixture of oxygen and acetylene gas (Gas Flame) with or without application of pressure and with or without use of filler material. In OAW O2 and C2H2 are mixed and burnt to release heat.

REACTION:

C2H2 + 2.5O2 = CO2 + H2O + 1284.57 kJ/mol.

Why To Produce Flame in Oxy-Acetylene Welding?

In oxyacetylene welding, flame is the most important tool. All the welding equipment simply serves to maintain and control the flame. The correct type of flame is essential for the production of satisfactory welds. The flame must be of the proper size, shape and condition in order to operate with maximum efficiency.

Types of Flame (or Oxy acetylene Flame settings)

1. Neutral Flame

2. Carburizing Flame

3. Oxidizing Flame

1. Neutral Flame

The neutral flame as shown in above figure is produced when the ratio of oxygen to acetylene, in the mixture leaving the torch, is almost exactly one-to-one. It’s termed"neutral” because it will usually have no chemical effect on the metal being welded. It will not oxidize the weld metal; it will not cause an increase in the carbon content of the weld metal. As shown in figure 1.

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Figure 1: Neutral Flame

The neutral flame is commonly used for the welding of:

i) Mild Steel

ii) Stainless steel

iii) Cast iron

iv) Copper

v) Aluminum

2. Carburizing (or Reducing) Flame

The Carburizing (or Reducing) Flame, is created when the proportion of acetylene in the mixture is higher than that required to produce the neutral flame. A Carburizing flame has an approximate temperature of 5500°F (3038°C).

A reducing flame can be recognized by acetylene feather which exists between the inner cone and the outer envelope. The outer flame envelope is longer than that of the neutral flame and is usually much brighter in color. As shown in figure 2.

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Figure 2: Carburizing Flame

Use of Carburizing Flame:

With iron and steel it produces very hard, brittle substance known as iron carbide. This chemical change makes the metal unfit for many applications in which the weld may need to be bent or stretched.

Metals that tend to absorb carbon should not be welded with reducing flame.

3. Oxidizing Flame

The oxidizing flame results from burning a mixture which contains more oxygen than required for a neutral flame. It will oxidize or” burn” some of the metal being welded.

The outer flame envelope is much shorter and tends to fan out at the end on the other hand the neutral and carburizing envelopes tend to come to a sharp point.

An oxidizing flame tends to be hotter than the neutral flame. This is because of excess oxygen and which causes the temperature to rise as high as 6300°F.As shown in Figure 3.

[pic]

Figure3: Oxidizing Flame

The Oxidizing Flame is commonly used for the welding of:

i) Copper base metals

ii) Zinc base metals

iii) A few types of ferrous metals, such as manganese steel and cast iron

Comparison between All Three Flames:

[pic]

Figure 4

Figure 4 shows the comparison between all three types of flame.

Reference

•

• A Textbook of Production Technology by P.C.Sharma.

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Seminar Report on

TYPES OF FLAME

AT

Laljibhai Chaturbhai Institute of Technology

Bhandu-384 120

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Guided By Presented By

Prof.Y.L.Raol Akshay.P.Shah (Roll No.13)

B.E. Semester V (Mechanical Engineering)

Sept, 2011

SUBMITTED

Mechanical Engineering Department,

L. C. Institute of Technology, Bhandu.

Ta: Visnagar, Dist.: Mehsana-384 120.

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