Oxy-acetylene welding are design for cutting and joining (welding) purposes of metals. It was developed before the electric arc welding was in existence. oxy-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.
The following listed below are equipments used to carryout oxy-acetylene operation. They are:
- Acetylene gas cylinder
- Oxygen gas cylinder
- Oxygen pressure regulator
- Acetylene pressure regulator
- Oxygen gas hose
- Acetylene gas hose
- Welding torch or blow pipe
- Gas lighter
- Set of keys and spanners
- Filler rods and fluxes
- Protective clothing for the welder
This cylinder is usually painted maroon and the valves are screwed left handed. Acetylene cylinders are manufactured from drowned steel available in sizes of 300, 120, and 75 cubic feet. Acetylene cylinder pressure is 250 psi when filled. Acetylene is completely unstable in its pure form at pressure above 15psi which require a special porous material on the storage of acetylene. These materials can be balsa wood, charcoal, corn pith, or portland cement that is saturated with acetone to allow storage acetylene to be safe. The important of the porous materials is to prevent high-pressure gas forming in the cylinder. Acetone is a colourless, flammable liquid that is added to cylinder until about 40 percentage of the porous material is saturated.
Oxygen gas cylinder
Oxygen gas cylinder are painted green and the valves are screwed right handed. The cylinder are also made of high strength steel plate drowned to required size of 244, 122, and 80 cubic feets. Oxygen are stored within the cylinder at a pressure of 2200 psi. When the original pressure of a full oxygen cylinder drops by 10% during welding. This is to indicate that 1/10th of the cylinder content have been consumed.
Gas Welding pressure regulators
Pressure regulators are connected between the cylinder and the house that lead to the welding torch. Pressure needed for the welding torch maybe somewhere up to 35psig for oxygen and 15psig for acetylene. The pressure of the gases obtained from the cylinders is considerations higher than the gas pressure used to operate the welding torch. The primary function of the pressure Regulators is to reduce the higher pressure of the gas in the cylinder to a desired working pressure and to produce Steady flow of gas under varying cylinder pressures. The pressure regulator is fitted with two pressure gauges. One of it indicates the gas pressure in the cylinder and the shows the amount of level at which the gas is going out. Gas pressure can be classified into, Single stage regulator and two stage regulators.
GAS HOSES & CLAMPS:
Hose makes connection between the torch and the regulators. so it is expected to be strong, light, nonporous, and flexible enough for free movement of torch. The holes consist of the fuel hose and oxygen hole joined together side by side. common types of welding and cutting hose are twin and double hose, their size are determined by their inside diameter and their size to use depends on the type of work for which is intended for example hose used for light work has a 3/16 or 1/4 inch inside diameter and one or two plies of fabric while heavy-duty welding and cutting operations uses hose with diameter of 5/16 inch and three to four plies of fabric.
Hose clamp are made of metal materials used to clip the welding hose to a nipple. There are basically two types of connections namely; Jubilee clip and crimped connector. the crimped connector seems to be much safer than of jubilee clip which is properbly safer as it is harder of this type of connection to come loose.
The primary function of a check valve is to allow the flow of gas in one direction and to prevent flame or oxygen-fuel mixture being pushed back into the cylinder and causing backfire,flashback and explosion. it is positioned at the torch inlet, and at the regulator outlet.
note: A backfire is caused by the flame going out suddenly on the torch and it may occur when:
- The tip is touched against the work piece;
- If the flame setting is too low;
- If the tip is dirty, damage or loose, or;
- If the tip is overheated.
WELDING TORCH or BLOW PIPE
A welding torch mixes oxygen and acetylene mixing chamber. it burns the mixture at the tip of the torch and provodes a means of moving and directing the flame. The torch is also used to obtain different flame. There are two types of welding torches, namely:
a) High pressure (or equal pressure) type
b) Low pressure (or injector) type
High pressure blowpipes or torches are used with (dissolved) acetylene stored in cylinders at a pressure of 117 psi. Low pressure blowpipes are used with acetylene obtained from an acetylene generator at a pressure of 8 inch – head of water (approximately 0.3 psi).
In high pressure blow torch, both the oxygen and acetylene are fed at equal pressures and the gases are mixed in a mixing chamber prior to being fed to the nozzle tip. The high pressure torch also called the equal pressure torch is most commonly used because:
a) It is lighter and simpler;
b) It does not need an injector;
c) In operation, it is less troublesome since it does not suffer from backfires to the same extent.
Filler metals serve as additional materials to the pool when filling the gap and form intergral part to the weld.The purpose of the flux is to retard oxidation of the surfaces of the parts being welded, by generating gaseous shield around the weld zone.it also helps to dissolve and remove oxides and other substances from the work piece and so contributes to the formation of a stronger joint. The slag developed protects the molten metal puddles of metal against oxidation as it cools.. Filler rods nearly have the same chemical composition with the base metal and are available ina a variety of compositions and sizes. These consumable filler rod may be coated or bare with flux.
Characteristics of good flux
- lower melting point than parent metal.
- it has exactly the right fluidity when the welding temperature is reached.
- it protect the molten metal from atmospheric oxidation.
Spark lighter provides better, safe means of lighting a welding torch. it is never been advisable to use match stick because it puff the flame produced by the ignition of the acetylene flowing from the tip . it likely to burn the welder’s hand.
Gas Cylinder Trolleys
The trolley Serve as carriage of oxygen and acetylene cylinder. it is normally mounted on the trolley side to side held in place with chains and a support bottom made of chain. The trolley have two rubber tires or steel wheel rim wheels for easy movement.
eye goggles are used to protect welders eyes from harmful spark, heat and rediation of infrared and ultraviolet rays produce during welding.
Protective clothing (pron, Gloves & Safety Goggles)
Welding operators are expected to dress properly before operating the equipment. due to reaction of oxygen and acetylene, welder must wear proper gloves and use approved safety goggles or face shield which is to protect the eyes from sparks and flying hot metal particles. The goggles or face shield use special lenses to protect the eyes form light damage. A variety of lenses are used depending on the type of welding or cutting that needs to be done, the type of material, and the thickness of the material.
And that is it for gas welding equipments, i hope you enjoyed reading it. remember to share your idea via our comment box and share via your social media handles.