OXY-ACETYLENE WELDING

OXY-ACETYLENE WELDING

In oxy-acetylene welding, a welding torch is used to weldmetals.Welding metal results when two pieces are heated toa temperature that produces a shared pool of molten metal.The molten pool is generally supplied with additional metalcalled filler. Filler material depends upon the metals to becalled filler. Filler material depends upon the metals to bewelded.

Oxy-acetylene gas welding is a group of welding processeswhich join metals by heating with a fuel gas flame or flareswith or without the application of pressure and with orwithout the use of filler metal.

APPARATUS

The apparatus used in gas welding consists basically:

i. Oxygen source and a acetylene gas source

(usually cylinders)

i. Two pressure regulators

Two flexible hoses (one of each for each cylinder)ii. Two flexible hoses (one of each for each cylinder)

iii. A torch.

LOW-PRESSURE AND HIGHPRESSURE GAS WELDING

There are two types of gas welding, namely:

i. i. Low-pressure gas welding

ii. ii. High-pressure gas welding..

Low-pressure gas welding supply asetilina received from thegas generator asetilina a pressure less than 1.0 psi or 1.0bar.

High pressure gas welding receive gas supply from gas firedasetilina with pressure from 1-15psi or 1-15 bar

ACETYLENE Acetylene is the primary fuel for oxy-fuel welding and is the

fuel of choice for repair work and general cutting and welding.

Acetylene gas is shipped in special cylinders designed to keepthe gas dissolved.

The cylinders are packed with porous materials (e.g. kapokfibre, diatomaceous earth, or (formerly) asbestos), then filledfibre, diatomaceous earth, or (formerly) asbestos), then filledto around 50% capacity with acetone, as acetylene is acetonesoluble.

ACETYLENE CYLINDERS

These cylinders contain Acetylene under pressure, arepainted black, made of steel and have cylinder valves.

The cylinders contain a porous filler material which iswetted with acetone that allows the Acetylene to safely becontained in the cylinder at 250 psig.contained in the cylinder at 250 psig.

Acetylene should never be used at a pressure that exceeds15 psig as it becomes highly unstable which, depending onthe condition, could cause it to decompose and explode.

OXYGEN GAS Oxygen gas has no color, taste and smell. It is also a gas that

can assist in the combustion process, and also an active gascan interact with the metals that cause oxidation occurs onthe metal. For example, corrosion of the steel

OXYGEN GAS PRODUCTION

Oxygen gas can be produced through several methods,namely:

i) air distillation method. (Air staging)

ii) electrolysis method

AIR DISTILLATION METHOD

Air distillation method is a method of doing thiscommercially. This is done through the oxygen from the airseparation process called distillation of liquid air beingcompressed in the stress 206 bar (3000psi), which is at atemperature of -160 ⁰ C. Next the pressure will be reducedtemperature of -160 ⁰ C. Next the pressure will be reducedgradually in liquid form in which oxygen is converted into agas and is allowable. That's for the other gases will beconverted to gas when the pressure is reduced and isallowable for other uses.

ELECTROLYSIS METHOD Electrolysis method is a process of producing oxygen gas

obtained by electrical currents in the water. This process isvery expensive and not economical for commercialization.Oxygen will be stored in steel cylinders that are black andmore than asetilina cylinder. It is not connected and able tomore than asetilina cylinder. It is not connected and able towithstand pressure up to 3360 psi.Available in three sizes

OXYGEN CYLINDERS These cylinders are made of steel and are usually painted

green.

If Oxygen comes into contact with oil or grease, it willburst into flame. Never use oil or grease on Oxygencylinder valves or regulators.cylinder valves or regulators.

Crack open the cylinder valve then close it before installingthe regulator to clear the valve of any dirt.With theregulator installed, always crack the cylinder valve openfirst, then open it fully..

GAS HOSES The hoses used are specifically designed for welding and cutting.

The hose is usually a double-hose design, meaning that there aretwo hoses joined together.

The oxygen hose is green and the fuel hose is red.The type ofgas the hose will be carrying is important because thegas the hose will be carrying is important because theconnections will have different threads for different types of gas.

Fuel gases (red) will use left-hand threads and a groove cut intothe nut, while the oxygen (green) will use right-hand threads.This is a safety precaution to prevent hoses from being hookedup the wrong way. [2]

REGULATOR The regulator is used to control pressure from the tanks by

reducing pressure and regulating flow rate. Oxy-gasregulators usually have two stages:

The first stage of the regulator releases the gas at a constantrate from the cylinder despite the pressure in the cylinderrate from the cylinder despite the pressure in the cylinderbecoming less as the gas in the cylinder is used.

The second stage of the regulator controls the pressurereduction from the intermediate pressure to low pressure.

There are two general types of regulators, single stage and twostage. Both perform the same function but the two stageregulator will supply a more constant pressure as the cylinderpressure falls by compensating for any drop in cylinder pressurebetter than will the single stage unit.Also, two stage regulatorsare usually more heavy duty in construction and will last longerare usually more heavy duty in construction and will last longerin heavy duty use and require less maintenance than the singlestage units.Two stage regulators can be identified by their secondpressure chamber where single stage units have only one.Oxygen and Acetylene regulators connect differently to theircylinders so they can not be mixed up. Oxygen regulators haveright hand threads and regulators for Acetylene and other fuelgases have left hand threads.

REGULATOR

FIRST STAGE REGULATOR

Skru pelarasInjap masuk

spring

1

Gas dari silinder

pelaras

diafram

Gas keluar untuk kimpalan

2

TWO STAGE REGULATOR

spring

Aliran gas masuk

Ruang tekanan tinggi

Aliran gas masuk

Ruang tekanan rendah

Skru pelaras

Aliran gas keluar untuk kerja

diafram

TORCHES The torch is the part that the welder holds and manipulates

to make the weld. It has a connection and valve for the fuelgas and a connection and valve for the oxygen, a handle forthe welder to grasp, a mixing chamber (set at an angle)where the fuel gas and oxygen mix, with a tip where thewhere the fuel gas and oxygen mix, with a tip where theflame forms.

TYPICAL TORCH STYLES

A small welding torch, with throttle valveslocated at the front end of the handle. Ideallysuited to sheet metal welding. Can be fittedwith cutting

attachment in place of the welding head attachment in place of the welding headshown. Welding torches of this general designare by far the most widely used. They willhandle any oxyacetylene welding job, can befitted with multiflame (Rosebud) heads forheating applications, and accommodate cuttingattachments that will cut steel 6 in. thick.

A full-size oxygen cutting torch which has allvalves located in its rear body. Another style ofcutting torch, with oxygen valves located at thefront end of its handle.

Badan sumpitan-api tekanan seimbang

Salu masuk gas asetilina

Salur masuk oksigen

Ruang percampuran

Gas keluar

Pelaras oksigen

Pelaras gas asetilina

Penyambung ke muncungsumpitan

Badan sumpitan-api tekanan seimbang

Badan sumpitan-api jenis injektor

Salur masuk oksigen

Salur masuk oksigen

Ruang percampuran

Ruang percampuran

Arah gas keluar

WELDING GAS MANIFOLD SYSTEMS

Manifol manifold system is a gas welding assembly in whichoxygen gas cylinders and a separate consolidated Acetylenecollected between the two. Allocation of gas for both will bechanneled through the steel pipe to each welding station.

For manifol of single cylinder of oxygen and Acetylene be For manifol of single cylinder of oxygen and Acetylene becoupled together in each welding station. But it has a securityfeature low and not very economical use of gas

Therefore manifol manifold features high security and savings ingas consumption compared to single manifol. Moreover, whenmany station operating simultaneously. Workspace at eachwelding station will also be more spacious and comfortable.

MANIFOLD SYSTEM DIAGRAM