Tungsten-Arc Gas Shielded Welding - (Vertical) Low Carbon Steel — SEG Awards Vocationally-Related Qualification Design and Technology Revision

    Tungsten-arc gas shielded welding (TAG) on low carbon steel in the vertical position requires understanding of safety legislation, equipment function, and

    Topic Synopsis

    Tungsten-arc gas shielded welding (TAG) on low carbon steel in the vertical position requires understanding of safety legislation, equipment function, and welding parameters. Learners must identify hazards, select appropriate tungsten and filler wires, and perform welds to specification.

    Key Concepts & Core Principles

    Exam Tips & Revision Strategies

    Common Misconceptions & Mistakes to Avoid

    Examiner Marking Points

    Tungsten-Arc Gas Shielded Welding - (Vertical) Low Carbon Steel

    SEG AWARDS
    vocational

    Tungsten-arc gas shielded welding (TAG) on low carbon steel in the vertical position requires understanding of safety legislation, equipment function, and welding parameters. Learners must identify hazards, select appropriate tungsten and filler wires, and perform welds to specification.

    1
    Learning Outcomes
    3
    Assessment Guidance
    3
    Key Skills
    1
    Key Terms
    5
    Assessment Criteria

    Assessment criteria

    SEG Awards Level 3 Diploma in Welding Techniques and Skills

    Topic Overview

    The SEG Awards Level 3 Diploma in Welding Techniques and Skills is a vocationally-related qualification designed for students aiming to become proficient welders in industries such as construction, manufacturing, and engineering. This diploma covers advanced welding processes, including Manual Metal Arc (MMA), Metal Inert Gas (MIG), and Tungsten Inert Gas (TIG) welding, along with health and safety regulations, material science, and quality control. Students develop practical skills in preparing joints, selecting appropriate welding parameters, and inspecting welds to meet industry standards like BS EN ISO 9606-1.

    This qualification is essential for those seeking careers as welding technicians, fabricators, or inspectors. It builds on foundational knowledge from Level 2 qualifications and provides a pathway to higher-level certifications or apprenticeships. The diploma emphasizes real-world application, requiring students to produce welded components to specification and understand the metallurgical principles behind different welding techniques. Mastery of these skills ensures employability in sectors where structural integrity is critical, such as oil and gas, automotive, and aerospace.

    Within the broader Design and Technology curriculum, this diploma integrates engineering principles with hands-on craftsmanship. Students learn to interpret technical drawings, calculate weld sizes, and apply non-destructive testing methods. The qualification also covers environmental considerations, such as fume extraction and waste management, aligning with modern sustainable practices. By the end of the course, students will be able to independently plan, execute, and evaluate welding projects, demonstrating competence in both theoretical knowledge and practical execution.

    Key Concepts

    Core ideas you must understand for this topic

    • →Welding Processes: Understand the principles and applications of MMA, MIG, and TIG welding, including equipment setup, electrode selection, and parameter adjustment (e.g., current, voltage, travel speed).
    • →Joint Preparation and Weld Symbols: Learn to prepare edges (e.g., bevel, V-groove) and interpret welding symbols on engineering drawings to ensure correct joint configuration and weld type.
    • →Material Science: Know how different metals (e.g., carbon steel, stainless steel, aluminium) behave under heat, including thermal expansion, phase changes, and potential defects like cracking or porosity.
    • →Health and Safety: Comply with COSHH regulations, use personal protective equipment (PPE) like welding helmets and gloves, and implement safe work practices to prevent burns, electric shock, and fume inhalation.
    • →Quality Control and Inspection: Perform visual inspection and use gauges to check weld dimensions, and understand non-destructive testing (NDT) methods such as dye penetrant or magnetic particle inspection.

    Learning Objectives

    What you need to know and understand

    • 1.1. Identify the responsibilities of both the employer and the employee when complying with the Health and Safety at Work Act 19741.2. Identify the use of current legislation, to include:• COSHH (Control of Substances Hazardous to Health)• PUWER (Provision and Use of Work Equipment)• RIDDOR (Reporting of Injuries, Diseases, and Dangerous Occurrences Regulations)1.3. Identify the use of a risk assessment procedure1.4. Identify safe working practices when using the TAG welding process, to include working:• in a confined space• at an height above 2 metres • with containers that have held chemicals or flammable liquids • in damp or wet conditions• with hazards from using high frequency units1.5. Describe the function of the equipment used in the TAG welding process, to include:• rectifier• inverter• high frequency units• welding lead cable and clamp• welding return cable and clamp• secondary earth and connector• torch• tungsten• collet• shroud• cooling system• gas supply, regulator and flow meter1.6. Identify suitable maintenance checks that would be required on the items listed in 2.11.7. State the procedures to be followed for the safe storage of welding equipment when the welding activity has been completed1.8. Identify a range of tungsten electrodes that are used for the TAG welding process, to include:• types used• size (diameter)• alloying additions• preparation of electrode tip (shape/dimensions)1.9. Identify a range of filler wires that are used for the TAG welding process, to include:• types used• size (diameter)• alloying additions1.10. Describe the effects of incorrect storage of tungsten electrode and filler wires1.11. State the effect of using damaged tungsten electrode and filler wires when carrying out welding activities1.12. Identify the shielding gas/es used in TAG welding1.13. Identify the function of the shielding gas used in TAG welding1.14. Identify and select the welding parameters to be used when welding in the vertical welding position (PF/PG):• welding current• torch slope and tilt angles• filler wire slope and tilt angles• shielding gas flow rate• arc length• speed of travel1.15. Identify the use of autogenous techniques when using the TAG welding process1.16. Identify suitable welding preparations for the type of joint and material thickness being welded1.17. Identify terms associated with welding preparations, to include:• included angle• angle of bevel• root face dimension• root gap dimension 1.18. Describe the application of distortion control techniques, to include: • pre-setting • restraint• joint geometry • chills• weld sequence1.19. Be able to follow instructions given on a WPS (Welding Procedure Sheet)1.20. Identify appropriate safety checks on the welding equipment prior to use1.21. Select suitable welding parameters to enable the listed joints to be welded by the TAG welding process on low carbon steel or stainless steel or aluminium• tee fillet (PF)• butt (PF)• open outside corner (PF or PG)• lap joint (PF or PG)1.22. Carry out visual inspection of completed welds1.23. Prepare and carry out nick break tests on completed fillet welds1.24. Prepare and carry out destructive tests on completed butt welds, to include:• face bend • root bend• fracture test 1.25. Record the results of the weld examination as detailed in 7.1, 7.2 and 7.31.26. Identify and describe typical defects found in the TAG welding process joints, to include:• cracks• inclusions• undercut• lack of fusion• arc craters• porosity• lack of penetration1.27. Identify possible causes of the defects listed in 8.1

    Assessment Criteria

    Key criteria assessors look for in your portfolio

    • Identify employer and employee responsibilities under HASAWA.
    • Describe the function of TAG welding equipment components.
    • Select correct welding parameters for vertical position.
    • Perform visual inspection and destructive tests on welds.
    • Identify and explain causes of common weld defects.

    Assessment Guidance

    Guidance for achieving higher grades

    • 💡Memorise key safety regulations and their purposes.
    • 💡Practice setting parameters for different joint types.
    • 💡Use diagrams to explain distortion control techniques.
    • 💡When answering theory questions, always reference specific British or European standards (e.g., BS EN 1011 for welding recommendations). This shows you understand the regulatory framework and can apply it to real scenarios.
    • 💡In practical assessments, demonstrate a systematic approach: check equipment settings, clean the workpiece, and perform a test run on scrap metal before welding the actual joint. Examiners award marks for methodical preparation and safety awareness.
    • 💡For questions on weld defects, use the correct terminology (e.g., 'undercut' not 'groove') and explain both the cause and remedy. Linking defects to welding parameters (e.g., excessive current causing spatter) shows deeper understanding.

    Common Mistakes

    Common errors to avoid in your coursework

    • Confusing COSHH with other regulations.
    • Incorrectly setting torch angles for vertical welding.
    • Failing to identify lack of fusion as a defect.
    • Misconception: 'MIG welding is easier than TIG, so it doesn't require as much skill.' Correction: While MIG is more forgiving on dirty materials, it still demands precise control of wire feed speed and gun angle to avoid lack of fusion or spatter. TIG requires finer manual dexterity, but both processes require significant practice to achieve consistent, high-quality welds.
    • Misconception: 'A bigger weld is always stronger.' Correction: Oversized welds can introduce excessive heat input, leading to distortion, residual stress, and reduced fatigue strength. Welds should be sized according to design specifications to balance strength and material integrity.
    • Misconception: 'Stainless steel doesn't rust, so no post-weld treatment is needed.' Correction: Welding can cause sensitization and carbide precipitation, reducing corrosion resistance. Proper cleaning, passivation, or use of low-carbon grades (e.g., 316L) is often required to maintain stainless steel's properties.

    Frequently Asked Questions

    Common questions students ask about this topic

    Before You Start

    Prior knowledge that will help with this topic

    • •Level 2 Diploma in Welding or equivalent experience: Familiarity with basic welding techniques, safety procedures, and simple joint configurations is essential before tackling advanced processes.
    • •Basic Mathematics and Science: Understanding of geometry (angles, measurements) and physics (heat transfer, electricity) helps in calculating weld sizes and interpreting technical data.
    • •Engineering Drawing Interpretation: Ability to read and understand technical drawings, including symbols for welds, dimensions, and tolerances, is required for planning and executing welding tasks.

    Key Terminology

    Essential terms to know

    • 1.1. Identify the responsibilities of both the employer and the employee when complying with the Health and Safety at Work Act 19741.2. Identify the use of current legislation, to include:• COSHH (Control of Substances Hazardous to Health)• PUWER (Provision and Use of Work Equipment)• RIDDOR (Reporting of Injuries, Diseases, and Dangerous Occurrences Regulations)1.3. Identify the use of a risk assessment procedure1.4. Identify safe working practices when using the TAG welding process, to include working:• in a confined space• at an height above 2 metres • with containers that have held chemicals or flammable liquids • in damp or wet conditions• with hazards from using high frequency units1.5. Describe the function of the equipment used in the TAG welding process, to include:• rectifier• inverter• high frequency units• welding lead cable and clamp• welding return cable and clamp• secondary earth and connector• torch• tungsten• collet• shroud• cooling system• gas supply, regulator and flow meter1.6. Identify suitable maintenance checks that would be required on the items listed in 2.11.7. State the procedures to be followed for the safe storage of welding equipment when the welding activity has been completed1.8. Identify a range of tungsten electrodes that are used for the TAG welding process, to include:• types used• size (diameter)• alloying additions• preparation of electrode tip (shape/dimensions)1.9. Identify a range of filler wires that are used for the TAG welding process, to include:• types used• size (diameter)• alloying additions1.10. Describe the effects of incorrect storage of tungsten electrode and filler wires1.11. State the effect of using damaged tungsten electrode and filler wires when carrying out welding activities1.12. Identify the shielding gas/es used in TAG welding1.13. Identify the function of the shielding gas used in TAG welding1.14. Identify and select the welding parameters to be used when welding in the vertical welding position (PF/PG):• welding current• torch slope and tilt angles• filler wire slope and tilt angles• shielding gas flow rate• arc length• speed of travel1.15. Identify the use of autogenous techniques when using the TAG welding process1.16. Identify suitable welding preparations for the type of joint and material thickness being welded1.17. Identify terms associated with welding preparations, to include:• included angle• angle of bevel• root face dimension• root gap dimension 1.18. Describe the application of distortion control techniques, to include: • pre-setting • restraint• joint geometry • chills• weld sequence1.19. Be able to follow instructions given on a WPS (Welding Procedure Sheet)1.20. Identify appropriate safety checks on the welding equipment prior to use1.21. Select suitable welding parameters to enable the listed joints to be welded by the TAG welding process on low carbon steel or stainless steel or aluminium• tee fillet (PF)• butt (PF)• open outside corner (PF or PG)• lap joint (PF or PG)1.22. Carry out visual inspection of completed welds1.23. Prepare and carry out nick break tests on completed fillet welds1.24. Prepare and carry out destructive tests on completed butt welds, to include:• face bend • root bend• fracture test 1.25. Record the results of the weld examination as detailed in 7.1, 7.2 and 7.31.26. Identify and describe typical defects found in the TAG welding process joints, to include:• cracks• inclusions• undercut• lack of fusion• arc craters• porosity• lack of penetration1.27. Identify possible causes of the defects listed in 8.1

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