SAMPLEMEM05 Metal and Engineering Training Package Learner Guide Version 1 Training and Education...

MEM05 Metal and Engineering Training Package

Learner Guide Version 1

Training and Education Support Industry Skills Unit

Meadowbank

MEM05026C Apply welding principles

Product Code: 5672

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Page 3 of 342 © TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2012

Acknowledgments

The TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank would like to acknowledge the support and assistance of the following people in the production of this learner resource guide:

• BOC Gases Australia • Standards Australia • CIGWELD/Thermadyne Australia • Lincoln Electric Company Australia • Fronius Australia • Silverwater Welding Supplies • Welding Industries of Australia Writer Ed Harkness (From existing TAFE publications)

Reviewer Vince Aranda (Illawarra Institute) Peter Stauffer (Hunter Institute)

Project Manager: Stephen Davies Educational Program Manager TAFE NSW

Enquiries Enquiries about this and other publications can be made to:

Training and Education Support Industry Skills Unit, Meadowbank Meadowbank TAFE Level 3, Building J, See Street, MEADOWBANK NSW 2114

Tel: 02-9942 3200 Fax: 02-9942 3257

ISBN 978-1-74236-380-6

© The State of New South Wales, Department of Education and Training, TAFE NSW, Training and Education Support Industry Skills

Unit, Meadowbank, 2012.

Copyright of this material is reserved to TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank. Reproduction or transmittal in whole or in part, other than for the purposes of private study or research, and subject to the provisions of the Copyright Act, is prohibited without the written authority of, TAFE NSW. Training and Education Support Industry Skills Unit, Meadowbank.

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Table of contents

General introduction ............................................................................. 11

Assessment (How you will be assessed) ............................................................... 14

Recognition of prior learning (RPL) ....................................................................... 14

Unit mapping .................................................................................................... 14

Elements and performance criteria ....................................................................... 16

Access and equity considerations ......................................................................... 16

Context of and specific resources for assessment ................................................... 17

Work health and safety (WHS) ............................................................................ 17

What you will need ............................................................................................ 17

Topic 1: Welding regulations ................................................................. 21

Introduction ...................................................................................................... 21

Certification of welders and welding supervisors AS 1796—2001.............................. 22

Workplace health and safety (WHS) ..................................................................... 23

Review questions ............................................................................................... 24

Topic 2: Welding safety ......................................................................... 27

Introduction ...................................................................................................... 27

Hazards ............................................................................................................ 27

Hazardous locations ........................................................................................... 28

Industrial gas cylinders ...................................................................................... 34

Scaffolding ........................................................................................................ 37

Skin and eye damage prevention ......................................................................... 37

Protective clothing and equipment (PPE) ............................................................... 39

X-ray and gamma-ray radiation ........................................................................... 40

Industrial injuries .............................................................................................. 40


Topic 3: Electrical terms ........................................................................ 43

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Introduction ...................................................................................................... 43

Types of welding current..................................................................................... 44

High frequency machines (HF) ............................................................................. 47

Constant current (drooping voltage) welding machine ............................................ 48

Constant potential (flat) welding machine ............................................................. 50

Motor generators ............................................................................................... 50

Other equipment ............................................................................................... 52


Topic 4: Arc welding conditions ............................................................. 61

Introduction ...................................................................................................... 61

Current/amperage ............................................................................................. 61

Polarity ............................................................................................................. 63


Topic 5: Manual metal arc welding electrodes ....................................... 69

Introduction ...................................................................................................... 69

Covered electrodes ............................................................................................ 69

Electrode classification ....................................................................................... 70

Type of flux coatings .......................................................................................... 73

Storage, handling and conditioning electrodes ....................................................... 76


Topic 6: Elements in carbon steel .......................................................... 81

Introduction ...................................................................................................... 81

Weldability of carbon steels ................................................................................. 81

Influence of elements on weldability of carbon steels ............................................. 84


Topic 7: Heat treatment ........................................................................ 91

Introduction ...................................................................................................... 91

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Effects of welding heat on carbon steels ............................................................... 92

Effects of heat on mechanical properties ............................................................... 94

Heat treatments ................................................................................................ 94

Heating methods ............................................................................................... 97

Temperature measuring devices .......................................................................... 99

Review questions ............................................................................................. 103

Topic 8: Welding terms and symbols ................................................... 105

Introduction .................................................................................................... 105

Types of welds ................................................................................................ 105

Parts of a weld and general terms ...................................................................... 107

Parts of a weld preparation ............................................................................... 110

Weld positions ................................................................................................. 112

Welding symbols ............................................................................................. 114


Topic 9: Preparing weld joints ............................................................. 123

Introduction .................................................................................................... 123

Edge preparations ............................................................................................ 123

Types of edge preparations ............................................................................... 124

Fusible inserts ................................................................................................. 127

Methods of preparing joints ............................................................................... 128

Jigs and fixtures .............................................................................................. 129


Topic 10: Metal cutting and gouging ................................................... 133

Introduction .................................................................................................... 133

Preparing metal parts for welding ...................................................................... 133

Cutting equipment ........................................................................................... 135

Guided cutting ................................................................................................. 138

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Oxygen-fuel gas gouging .................................................................................. 140

Applications .................................................................................................... 140

Automated thermal cutting ............................................................................... 143

Electrode holder .............................................................................................. 152

Operating techniques ....................................................................................... 153

Hazards associated with plasma cutting .............................................................. 160

Maintenance of equipment ................................................................................ 161

Mechanical cutting ........................................................................................... 161


Topic 11: Welding procedures ............................................................. 167

Introduction .................................................................................................... 167

Proving a welding procedure ............................................................................. 167

Types of welding procedures ............................................................................. 168


Topic 12: Weld testing ........................................................................ 177

Introduction .................................................................................................... 177

Types of weld testing ....................................................................................... 177

Destructive testing ........................................................................................... 177

Non-destructive testing methods ....................................................................... 185

Weld faults ..................................................................................................... 189


Topic 13: Welding alloy steels ............................................................. 199

Introduction .................................................................................................... 199

Physical and Mechanical properties .................................................................... 199

Alloy steels ..................................................................................................... 199

Effects of alloying elements when added to steel ................................................. 203

Welding processes for joining low alloy steels ...................................................... 209

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Welding processes for joining high alloy steels .................................................... 210


Topic 14: Non-ferrous metals .............................................................. 219

Introduction .................................................................................................... 219

Types of non-ferrous metals .............................................................................. 219

Aluminium and its alloys ................................................................................... 219

Copper and its alloys ........................................................................................ 223

Nickel and nickel alloys ..................................................................................... 226

Cutting non-ferrous metals ............................................................................... 228

Safety precautions for welding non-ferrous metals ............................................... 229


Topic 15: Gas tungsten arc welding (GTAW) ....................................... 235

Introduction .................................................................................................... 235

The process .................................................................................................... 235

Equipment ...................................................................................................... 237

Polarity and current ......................................................................................... 247

Weld joints ..................................................................................................... 251

GTAW safety ................................................................................................... 255


Topic 16: Gas metal arc welding (GMAW) and Flux cored arc welding (FCAW) ............................................................................................... 261

Introduction .................................................................................................... 261

The GMAW process .......................................................................................... 261

Welding guns .................................................................................................. 265

Welding variables ............................................................................................ 268

Correcting weld and machine faults .................................................................... 279

Safety ............................................................................................................ 282

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Flux cored arc welding (FCAW) .......................................................................... 283


Topic 17: Submerged arc welding (SAW) ............................................ 293

How the process works ..................................................................................... 293

Equipment ...................................................................................................... 293

Consumables .................................................................................................. 298

Effects of SAW variables ................................................................................... 300

Edge preparations ............................................................................................ 302

Advantages and limitations of SAW .................................................................... 304

Typical SAW faults ........................................................................................... 306

SAW safety ..................................................................................................... 307

Electro-slag welding (consumable guide) ............................................................ 308


Topic 18: Oxyacetylene welding (OAW) .............................................. 315

The OAW process ............................................................................................. 315

Equipment for OAW ......................................................................................... 316

Welding torches ............................................................................................... 323

Oxyacetylene welding advantages and limitations of ............................................ 329

OAW weld faults .............................................................................................. 330

Low temperature welding processes ................................................................... 330

Consumables .................................................................................................. 332

Applications for brazing .................................................................................... 333

Review questions ............................................................................................. 334 SAMP

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• All workers should develop their ability to work in a culturally diverse environment

• In recognition of particular issues facing Aboriginal and Torres Strait Islander communities, workers should be aware of cultural, historical and current issues impacting on Aboriginal and Torres Strait Islander people

• Assessors and trainers must take into account relevant access and equity issues, in particular relating to factors impacting on Aboriginal and/or Torres Strait Islander clients and communities.

Context of and specific resources for assessment This unit may be assessed on the job, off the job or a combination of both on and off the job. Where assessment occurs off the job, that is the candidate is not in productive work, then an appropriate simulation must be used where the range of conditions reflects realistic workplace situations. The competencies covered by this unit would be demonstrated by an individual working alone or as part of a team. The assessment environment should not disadvantage the candidate.

Work health and safety (WHS) Your teacher will encourage you to assist in identifying/eliminating hazards and to devise control measures for potential risks to yourself and others that may arise during practical sessions. The Work, Health and Safety Act 2011 (WHS Act) and WHS Regulations are enforced throughout all Australian States and Territories.

This legislation is aimed at providing consistency, certainty and clarity across Australia making it easy to understand workplace health and safety responsibilities. The WHS Act and its regulations will require both teachers and learners to take reasonable steps to control and monitor potential risks in the classroom, practical workshops and in the workplace. Detailed information relating to the WHS Act and regulations can be found on the following websites:

• WorkCover Authority of NSW www.workcover.nsw.gov.au

• Safe Work Australia www.safeworkaustralia.gov.au

What you will need Students will require the following:

• pens, pencils and calculator

• learner resource MEM05026C Apply welding principles

Wallet card Upon successful completion of this knowledge based unit and at least one (1) of the following practical competency units from the MEM05 Training Package (see list below) you will be eligible to receive a TAFE NSW issued wallet card to AS 1796 Welder Certifications:

• MEM05042B Perform welds to code standards using flux core arc welding process

• MEM05043B Perform welds to code standards using gas metal arc welding process

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http://www.workcover.nsw.gov.au/http://www.safeworkaustralia.gov.au/



• MEM05044B Perform welds to code standards using gas tungsten arc welding process

• MEM05045B Perform pipe welds to code standards using manual metal arc welding process

• MEM05046B Perform welds to code standards using manual metal arc welding process.

Figure: Sample AS1796 Welding certification cards (front and reverse)

An AS 1796 wallet card is a requirement for operators engaged in the welding and manufacture of pressure equipment such as pressure vessels and piping etc. To obtain an AS 1796 Welder Certification card you will need to co-enrol in 17622 TAFE PLUS Assessment course and appropriate module. Your TAFE NSW teaching section will best advise you of the cost and correct assessment module you need to be enrolled in to receive the correct certificate. Your teaching section will record, process and pass-on all relevant information to the company who supplies TAFE NSW issued certification cards.

Certificates 1-9

In accordance with AS 1796-2001 there are 9 Certificates available. These are listed in the following table.

Table: Certificates 1-9 available in accordance with AS 1796-2001

Certificate No Title

All MEM05026C Apply welding principles (theory)

1 Manual metal arc welding (MMAW) of welds in carbon steel plate and carbon steel pipe over 600 mm outside diameter, single vee welded from both sides.

1E Manual metal arc welding (MMAW) of welds in carbon steel plate and carbon steel pipe over 270 mm outside diameter, single vee welded from one side only.

2 Manual metal arc welding (MMAW) of welds in carbon steel piper, single vee weld from one side only.

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Note: For further details see Section 2 Welder Certification (AS 1796-2001)

3 Manual metal arc welding (MMAW) of welds using hydrogen controlled electrodes in alloy steel plate and alloy steel pipe over 600 mm outside diameter, single vee welded from both sides.

3E Manual metal arc welding (MMAW) of welds using hydrogen controlled electrodes in alloy steel plate and alloy steel pipe over 270 mm outside diameter, single vee welded from one side only.

4 Manual metal arc welding (MMAW) of welds using hydrogen controlled electrodes in alloy steel pipe, single vee welded from one side only.

5 Gas tungsten arc welding (GTAW) root run and manual metal arc welding (MMAW) using hydrogen controlled electrodes in alloy steel pipe, single vee welded from one side only.

6 Gas welding (GW), single vee welded from one side only.

7 Gas tungsten arc welding (GTAW), single vee welded from one side only.

8F Flux cored arc welding (FCAW) on plate and pipe.

8G Gas metal arc welding (GMAW) on plate and pipe.

9 Automatic welding (submerged arc welding process).

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Topic 12: Weld testing

Introduction This topic enables you to identify weld defects and select the appropriate testing method to locate them.

Types of weld testing When welded structures are subjected to heavy loads, or required to perform in demanding conditions, the integrity of the structure must be proved before being placed into service. To ensure quality, both the material and welded joint must be subjected to some form of testing. As a result inspection and testing form an important part of a welding procedure.

No weld is completely without faults. The structure is accepted or rejected on the basis of the level of permissible imperfections found. The level will vary according to the nature of the finished work. The relevant standard or specification will specify quality requirements.

Regulations covering weld testing are strictly enforced on welded structures such as in pressure vessels, boilers, pressure piping and many areas of metal construction.

Weld testing can be carried out using either:

• destructive testing (DT)

• non-destructive testing (NDT).

Destructive testing Destructive testing can be divided into two categories; workshop testing and laboratory testing. Test results provide an indication or a measurement of the mechanical properties of the welded joint.

Workshop testing

Workshop tests are carried out using equipment found in most fabrication shops. These tests are designed to provide an indication of ductility, tensile strength and proof of full fusion in the welded joint.

Laboratory testing

Laboratory tests require specialised equipment to measure the tensile strength, ductility, impact strength and hardness of test specimens. Some large manufacturers employ their own testing laboratories and technical staff to perform such tests. Smaller companies often call in specialist contractors to carry out their testing requirements.

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Destructive tests are designed to break or bend weld samples, therefore these tests cannot be performed on finished work. For this reason test plates of the same quality and thickness as the job under construction are used. Production tests plates are attached to a pressure vessel in line with its longitudinal joints and completed as part of the job. An example of a weld test plate is shown below.

Figure: Longitudinal weld test plate

After welding, test plates are removed and prepared for mechanical testing. If heat treatment is required on the finished vessel the test plate will also be heat treated with the finished vessel or subjected to the same heat treatment conditions before tests are carried out. This procedure will give an accurate reproduction of the properties of the welded structure. The numbered test specimens indicated on the test plate shown above are explained in the table following.

Table: Numbered test specimens indicated on the test plate

Number Type of test

1 All weld metal tensile test specimen

2 Macro test specimen

3 Transverse tensile test specimen

4 Face bend test specimen

5 Root bend test specimen

6 Impact test specimens

7 Longitudinal bend test specimen

8 Nick break test specimen

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The numbered test pieces cut from this test plate are required for a series of destructive tests. These include the following:

Nick break specimen (#8)

The specimen may be broken manually or mechanically to examine the internal quality of the weld. For the example shown below, W = width of sample = 25 mm.

Figure: Nick break test

Examination of the broken sample will reveal the presence of any internal weld defects such as the ones listed below:

• porosity

• lack of fusion

• slag inclusions if applicable.

Bend tests

Face and root bend tests are used to indicate the ductility of a weld. During face bending the weld face is subjected to tension whereas root bends are designed to subject the root of the weld to a similar tension. Normally bend test specimens are bent through to 180°.

Due to the stretching and stress placed on the weld area during a bend test, any lack of fusion will soon become evident using resulting in the specimen forming a visible tear or worse, fracturing and failing the test.

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Face bend test (#4)

Figure: Bend test

Figure: Face bend Figure: Root bend

Side bend tests are also conducted on gas metal arc welded joints to prove the soundness of side wall fusion of the welded joint.

Tensile Test

Tensile testing requires the specimen to be pulled apart until it fractures. Equipment used to perform this test measures the applied force and the change in length (elongation) of the specimen during testing. Specimens may be prepared for either transverse tensile or all weld metal tensile testing. All weld metal testing determines the tensile strength of the weld metal, elongation and reduction in sectional area before fracture. These measurements are designed to indicate the ductility of the weld joint or weld deposit.

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SAMPLEMEM05 Metal and Engineering Training Package Learner Guide Version 1 Training and Education...

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