WELDING LEVEL 4 - PowerPoint Presentation

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WELDING LEVEL 4

MALUTI TVET COLLEGELECTURER : MJ MOTAUNG

TOPIC :5 UNIT :1

GAS TUNGSTEN ARC WELDING

LO :Explain the terminologies associated with gas tungsten arc welding procedure.Briefly explain the actual chemical and mechanical processes that take place during welding.Explain the gas tungsten arc welding (GTAW) method.Identify the various welding parameters, in relation to the thickness of materials (steel) being welded.Demonstrate setting up procedures.

INTRODUCTION

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode is protected from oxidation or other atmospheric contamination by an inert shielding gas (argon or helium), and a filler metal is normally used, though some welds, known as autogenous welds, do not require it

GTAW welding is used mostly on pipes.Below is example of pipe

TERMINOLOGIES ASSOCIATED WITH THE GAS TUNGSTEN ARC WELDING PROCEDURES

Tungsten Inert Gas, also known as GTAW,

Gas Tungsten Arc Welding) welding uses a non-melting electrode made of tungsten in combination with filler metal rod to create the weld. Gas Hazards . Shielding gases used in arc welding are inert. The primary health hazard with these gases is the potential for displacement of breathing air .It produces no slag, sparks, spatter or fumes and does not require any flux. Advantages of the (GTAW) process : disadvantages of the GTAW process :

High quality welds are produced. The equipment is expensive.Nearly all metals and all alloys can be welded. The process require a higher degree of skill.All weld positions are possible. It is slower than other processes.

No slag is developed. It produces brighter UV rays which can be harmful if the The is no spatter. welder is careless.

CHEMICAL AND MECHANICAL PROCESSES THAT TAKE PLACE DURING WELDING

A low voltage high current, continuous arc is formed between a tungsten electrode on the welding torch and the work .The electric arc is produced by the current moving through an inert gas ( argon or helium) .The inert gas not only provides a suitable arc , it also displaces the air, shielding the weld pool and the electrode from atmospheric contaminants.

Gas tungsten arc welding machine method

Gas tungsten arc welding is the solution for more weld control and precision. It allows you to weld thinner material, provides excellent fusion, and solves problems related to melt-through or warping that are more common in GMAW .Gas tungsten arc welding also produces the best looking weld beads. Gas tungsten arc welding especially in tubing applications helps overcome some of the drawbacks of GMAW. Instead of needing to maintain a consistent travel speed or risk incomplete fusion

Welding parameters in relation to the thickness of materials (steel) being welded

The primary variables in GTAW are:

Arc voltage arc length.Welding current.Travel speed.Sheilding gas.

Setting up procedure for GTAW

Make sure the welding power supply is located in a dry area and that it is switched off.

Ensure that the inert gas cylinder is secured with a safety chain so that it will not tip over.Remove the cylinder cap.With the valve opening pointed away from you, open the valve slightly for just a moment and then close it. With the valve opening pointed away from you, open the valve slightly for just a moment to remove any dirt and then close it.Using a wrench or spanner, attach the regulator to the cylinder.

Connect the gas hoses.If the system is water cooled, connect the water linesComplete the electrical power and control connections between the torch and the welding power supply.

Insert the electrode in the torch collet and tighten, Install the cup (nozzle ) if need be.Check for inert gas and water leaks and tighten fittings if needed, then adjust the gas for proper flow rate.Set current level,polarity and secure the work lead to the work.

LEARNING ACTIVITY

page 179 of textbook supplied by the collage. Activity 5.1

PLEASE FEEL FREE TO CONTACT ME ON MY WHATSUP FOR ANY QUESTIONS THAT YOU MAY HAVE. OUR NEXT PRESENTATION WILL BE PLAN AND PREPARE FOR THE GTAW PROCESS