Oxyfuel-Gas Welding

Do you ever feel like you know just enough about Oxyfuel-Gas Welding to be dangerous? Let's see if we can fill in some of the gaps with the latest info from Oxyfuel-Gas Welding experts.

I trust that what you've read so far has been informative. The following section should go a long way toward clearing up any uncertainty that may remain.

Oxyfuel-gas welding (OFW) is a general term used to describe any welding process that uses a fuel gas combined with oxygen to produce a flame. This flame is the source of the heat that is used to melt the metals at the joint. The most common gas welding process uses acetylene; this process is known as oxyacetylene-gas welding (OAW) and is used typically for structural sheet-metal fabrication, automotive bodies, and various repair work. This reaction consists of the further burning of both the hydrogen and the carbon monoxide and produces about two-thirds of the total heat.

Three basic types of oxyacetylene flames used in Oxyfuel-Gas Welding and cutting operations

1. neutral flame;


2. oxidizing flame;


3. carburizing or reducing flame.

[caption id="attachment_383" align="aligncenter" width="456" caption="Three basic types of oxyacetylene flames used in oxyfuel-gas welding and cutting operations"][/caption]

The gas mixture in (a) is basically equal volumes of oxygen and acetylene. (d) The principle of the oxyfuel-gas welding operation.

Oxyfuel-Gas Welding Flame types:

1. The proportion of acetylene and oxygen in the gas mixture is an important factor in oxyfuel-gas welding.


2. A flame with excess oxygen is known as an oxidizing flame.


3. Only in the welding of copper and copper-based alloys is an oxidizing flame desirable, because in those cases, a thin protective layer of slag (compounds of oxides) forms over the molten metal.


4. Other fuel gases (such as hydrogen and methylacetylene propadiene) also can be used in oxyfuel-gas welding.

Oxyfuel-Gas Welding Filler metals

1. Filler metals are used to supply additional metal to the weld zone during welding.


2. They are available as filler rods or wire and may be bare or coated with flux.


3. The purpose of the flux is to retard oxidation of the surfaces of the parts being welded by generating a gaseous shield around the weld zone.

Oxyfuel-Gas Welding practice and equipment

1. Oxyfuel-gas welding can be used with most ferrous and nonferrous metals for almost any workpiece thickness, but the relatively low heat input limits the process to thicknesses of less than 6 mm.


2. Figure shows the (a) General view of and (b) cross-section of a torch used in oxyacetylene welding. The acetylene valve is opened first; the gas is lit with a spark lighter or a pilot light; then the oxygen valve is opened; and the flame adjusted. (c) Basic equipment used in oxyfuel-gas welding. To ensure correct connections, all threads on acetylene fittings are left-handed, whereas those for oxygen are right-handed. Oxygen regulators usually are painted green and acetylene regulators red.


3. The basic steps can be summarized as follows:

• Prepare the edges to be joined and establish and maintain their proper position by using clamps and fixtures.


• Open the acetylene valve and ignite the gas at the tip of the torch. Open the oxygen valve and adjust the flame for that particular operation.


• Hold the torch at about 45° from the plane of the workpiece with the inner flame near the workpiece and the filler rod at about 30° to 40°.


• Touch the filler rod to the joint and control its movement along the joint length by observing the rate of melting and filling of the joint.

This article's coverage of the information is as complete as it can be today. But you should always leave open the possibility that future research could uncover new facts about Oxyfuel-Gas Welding.

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