Metal work

Introduction to oxygen acetylene welding

 

Oxygen acetylene welding are design for cutting and joining (welding) purposes of metals. It was developed before the electric arc welding was in existence. The oxygen acetylene welding has been available since the early 20th century still date which is capable of welding all types of metals including high quality ones. However, most industries now uses the electric arc welding methods because it offer greater speed than of the gas welding.

Fig 1.0. Show oxygen acetylene welding ready to use

Oxygen acetylene welding commonly called oxy-fuel welding or gas welding. It is the process in which fuel gases and oxygen are used to obtain different flames which are used for various purposes on metals, these includes joining (welding) and cutting operation. Oxygen acetylene welding was developed by some French engineers with the name, Edmond Fouché and Charles Picard in 1903. The gas welding was designed to use pure oxygen to increase the flame temperature which takes profound effect on metals properties. basically there are three major types of flames obtain in gas welding namely, carbonizing, neutralizing, and oxidizing. These three types of flame will be discuss on this same page.

Oxygen acetylene welding has ability to weld on all metals both ferrous (carbon steel) and non-metals (alloy steel, magnesium, cast iron, and aluminum). It component includes welding touch which is also called nozzle. The touch are designed to be adjusted to obtain different flames and allows the flame to be stable for brazing metals and cutting. Well, The touch is extensively explained below.

Components of Oxygen acetylene welding

  • Oxygen Cylinder
  • Acetylene Cylinder
  • Touch or Nozzle
  • Spark Lighter
  • Blow Pipes
  • Regulators
  • Welding gloves
  • Spindle Key
  • Trolley
  • Welding Goggles

Fig 3.2. Shows complete diagram of oxygen and acetylene with labels

Types of oxygen acetylene flames and their uses.

The following listed below are types of flames obtained from the adjustment of nozzle.

  • Corburizing Flame
  • Neutralizing Frame
  • Oxidizing Flame

Coburizing flame

Corborizing flame are commonly used to harden metal surface. This flame is obtain when excess amount acetylene is release than of oxygen.

Neutralizing flame

Neutralizing flame are used to melt misteel. The flame is obtain by the equal release of oxygen and acetylene.

Oxidizing flame

Oxidizing flame are commonly used when it comes to melting or boring holes on metals because the flames goes inside the core of a metal. This flame is obtain when excess of oxygen is released than of acetylene. These flames are mostly used on hard metals.

Fig above Shows the three types of flames produce with oxygen acetylene welding

Note: all these flames are gotten and adjusted from one same touch.

Basic uses of oxygen acetylene welding

Oxygen acetylene welding are used for various purposes on metals based on the type of metal and working operation. in this same page you’ll get to know the basic uses of oxygen acetylene welding.

  • Welding
  • Cutting

Welding

Welding is one of the essential operation carried out with Oxygen acetylene welding. It is the process of joining two or more pieces of metal together. This operation is done by the application of flame to the base metal at the desired weld bead. This welding requires welding rod or filler rod to the bead. It is advisable as a welder to keep the beads in same size and to know the amount of heat applied to the metal will determine the tip size, the welding position and the speed of travel.

Image Shows welding operation with oxygen acetylene welding

Cutting

The cutting operation is slight different from the welding operation. This operation is done when excess oxygen is released and small amount of acetylene is released from the touch. The touch is placed towards the desired cutting part on the metal until it start melting and some molten oxide will drop from the other side of metal. An acetylene is a flammable gas which produces flame through the touch and the purpose of oxygen is to mix with the acetylene gas and enables it to move with pressure through the touch.

Image Shows cutting operation with oxygen acetylene welding.

Roles of Oxygen and Acetylene

Because oxygen and acetylene functions differently, they seems to be kept in different cylinders to act better and safe condition. Well, the followings discussed below are the function of oxygen and acetylene.

Oxygen (oxy-gasoline)

Oxygen which is known as oxy-gasoline or oxy-petrol are kept in a black cylinder with white or grey shoulder. The oxygen are stored in the cylinder with a very high pressure (pressurize tank). It can be as high as 300 bar which is expected for the regulators to be able to absorb same pressure. Because oxy-gasoline is much released with little amount of acetylene the flame obtained easily melt metal piece of any thickness and drop down some molten oxide. The role of oxygen or oxy-gasoline in oxygen-acetlene welding is to push or transport acetylene at any desired pressure through a touch.

Acetylene

Acetylene is a gas that produces flame for gas welding. Acetylene cylinders are short, wide and usually painted with maroon color. All these cylinders carries the label of type of gas inside it. This fuel are used to repair, cutting and welding of metals. The cylinders are designed in such way that the acetylene gas dissolved. Inside the cylinder acetylene are packed with porous materials like kapok fibre, asbestos and diatomaceous earth, and filled around 50% capacity with acetone because acetylene is soluble in acetone. Acetylene are stores at lower pressure which is as low as 15bar. However, acetylenes are sold at very high cost when compared to other fuels.

Safety precaution in Oxygen acetylene welding

There are thing an oxygen acetylene operator must know as safety before he/she uses the welding equipment. These equipments are easy to use but hazardous when it comes to lack of safety knowledge about it. In this article, we’ve been able to bring out some safety points that need to be carryout and all operators must know how to control them. They includes:

  • Eye protection
  • Fuel Leakage
  • Flashback
  • Cylinder Capacity
  • Cylinder Safety
  • Chemical exposure

Eye protection

Considering the protecting of eyes when welding or cutting in oxygen acetylene welding is very important. The operator should always wear welding goggles before he/she start using the equipment. This is to protect the eyes against metal oxide, flying sparks and glare. However, the ultra-violet, infrared and blue light produce causes serious eye damage and bad eyestrain.

Fuel leakages

Leakages in oxygen acetylene welding often take place in holes and fittings either to the cylinder or touch. It is advisable for the operator to cross check all necessary joints and holes if no fuel leakage either with the use of soapy water or any positive possible means. As propane is denser than air leaking fittings easily catch fire and can cause damages to life and properties. Serious attention should be given when checking leakages to prevent ignition hazard.

Flashback

Flashback is when the particle (flame) are returning back to the holes. This could cause serious explosion if care is not taken and can cause injury or even kill the operator. Flashback is cause if lower pressure is used to pump the gas. To prevent flashback, flashback arrestor must be use. The operator should know how to properly off the flame that is, acetylene gas should be lock before the oxygen so that oxygen can push out the remaining acetylene inside the holes.

Cylinder Capacity

It is advisable for an operator to know the cylinder capacity. For example, 1/7 capacity of cylinder can work for an hour else the acetone inside the acetylene cylinder come out of the cylinder and contaminate the hose and touch.

Image Show Safety in oxygen acetylene welding

10 safety in oxygen acetylene welding

  • Do not allow the particles of the gas to remain in the hose after welding.
  • Welding should be done in a conducive area.
  • Proper ventilation.
  • The cylinders should be kept in a very cold atmosphere.
  • Never roll the cylinder on the floor, use trolley.
  • Tighten all necessary joints to make sure gas is unable to escape.
  • Use soapy water to check if the gas is licking.
  • Use trolley to move the cylinders from one point to another.
  • Acetylene should be off first after finish welding before the oxygen.
  • Note the color of the cylinders ( acetylene is painted either maroon or red and oxygen either blue or black).

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