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

    This topic covers tungsten-arc gas shielded welding (TAG) in the overhead position on low carbon steel, including health and safety, equipment, parameters,

    Topic Synopsis

    This topic covers tungsten-arc gas shielded welding (TAG) in the overhead position on low carbon steel, including health and safety, equipment, parameters, and quality control. Learners will perform welds and destructive tests.

    Key Concepts & Core Principles

    Exam Tips & Revision Strategies

    Common Misconceptions & Mistakes to Avoid

    Examiner Marking Points

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

    SEG AWARDS
    vocational

    This topic covers tungsten-arc gas shielded welding (TAG) in the overhead position on low carbon steel, including health and safety, equipment, parameters, and quality control. Learners will perform welds and destructive tests.

    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 comprehensive vocational qualification designed for students aiming to become proficient welders in the engineering and manufacturing sectors. This diploma covers advanced welding processes, including Manual Metal Arc (MMA), Metal Inert Gas (MIG), Tungsten Inert Gas (TIG), and Flux-Cored Arc Welding (FCAW), along with health and safety regulations, inspection techniques, and quality assurance. Students develop practical skills in preparing, setting up, and executing welds on various materials such as carbon steel, stainless steel, and aluminium, while also learning to interpret engineering drawings and welding symbols.

    This qualification is essential for those pursuing careers as welding technicians, fabricators, or inspectors, as it aligns with industry standards like ISO 9606 and EN 287. The diploma emphasises not only technical competence but also problem-solving, teamwork, and adherence to safety protocols, making it highly valued by employers. By mastering these skills, students contribute to the production of safe, durable structures and components in industries such as construction, automotive, aerospace, and shipbuilding.

    Within the broader Design and Technology curriculum, this diploma bridges theoretical knowledge with hands-on application, reinforcing principles of material science, thermodynamics, and structural integrity. It prepares students for further study or direct entry into the workforce, with opportunities to specialise in areas like pipe welding, robotic welding, or welding inspection. The course typically includes a mix of classroom instruction, workshop practice, and assessments that test both written understanding and practical competence.

    Key Concepts

    Core ideas you must understand for this topic

    • →Welding Processes: Understand the principles, advantages, and limitations of MMA, MIG, TIG, and FCAW, including appropriate applications for each.
    • →Joint Configurations and Welding Positions: Master the different joint types (butt, lap, T-joint, corner) and positions (flat, horizontal, vertical, overhead) as per ISO 6947.
    • →Weld Defects and Quality Control: Identify common defects like porosity, slag inclusion, undercut, and lack of fusion, and learn how to prevent them through proper technique and inspection.
    • →Health and Safety Regulations: Comply with COSHH, PPE requirements, fume extraction, and fire safety protocols to minimise risks in the welding environment.
    • →Material Preparation and Post-Weld Treatment: Know how to clean, bevel, and preheat materials, and understand stress relief and heat treatment processes to ensure weld integrity.

    Learning Objectives

    What you need to know and understand

    • 1.1. Identify the roles of various organisations involved with Health and safety in the workplace, to include:• Health and Safety Executive (HSE)• Environmental Health• Local Authorities1.2. Identify the roles of various individuals involved with Health and Safety in the workplace, to include:• Company safety officers• Company safety representatives• Environmental health officers• HSE inspectors1.3. Identify the purpose and typical contents of an organisations Health and Safety Policy1.4. Describe the purpose of a risk assessment, to include:• who should carry out risk assessments• when to carry out a risk assessment• identification of the 5 steps of risk assessment1.5. Identify the precautions to be taken when working in high risk areas, to include:• risk assessments• permits to work• high/low temperature working conditions• lock off systems• isolation of equipment1.6. Describe the control and safe removal of welding fumes and gases created during the welding process, to include:• natural extraction• local extraction• PPE and specialist breathing equipment1.7. Describe the hazards associated when using the TAG welding process, to include:• arc radiation• using high frequency• production of phosgene gas1.8. Identify the power sources used in TAG welding1.9. Identify the type of welding current (AC/DC) and polarity to be used when welding:• low carbon steel• stainless steel• aluminium1.10. Describe the application and use of equipment used in the TAG welding process, to include:• high frequency unit• current control foot pedal• gas pressure regulator• gas flow meter• gas lens1.11. Describe the importance of correct storage conditions for tungsten electrodes and filler wires, to include:• location• ventilation• contamination• labelling 1.12. Identify the range of different alloying elements added to tungsten electrodes1.13. Identify the electrode (tip) preparation required when using an AC or DC welding current1.14. Identify the content and application of a range of filler wires used in the TAG welding process1.15. Describe the effects of using damaged tungsten electrodes and filler wires1.16. Identify the range and application of shielding gases used in the TAG welding process1.17. Identify and select the welding parameters to be used when welding low carbon steel, stainless steel or aluminium in the overhead welding position (PE), to include:• welding voltage• slope in/slope out control• torch slope and tilt angles• high frequency• speed of travel• pre/post gas flow• shielding gas flow rate (LPM)1.18. Describe the application and function of gas backing /purging1.19. Identify suitable welding preparations for the type of joint and material thickness being welded, to include:• included angle• angle of bevel• root face dimension• root gap dimension1.20. Describe the advantages and limitations of the methods listed that are used to produce suitable welding preparations on materials, to include:• thermal methods• mechanical (chip forming)• shearing• bevelling machines• abrasive methods1.21. Identify the main types of distortion found in completed welded joints, to include:• longitudinal• transverse• angular1.22. Identify the main causes of distortion in welded joints1.23. Identify methods used to control distortion in welded joints1.24. Describe the significance of residual stress found in welded joints1.25. Identify appropriate safety checks on the welding equipment prior to use1.26. Select suitable welding parameters to enable the listed joints to be welded by the TAG welding process on one material type to cover, low carbon steel, stainless steel or aluminium in a thickness range of between 1.6 mm to 3 mm.• tee fillet (PE)• butt (PE)• open outside corner (PE)• lap joint (PE)1.27. Carry out destructive tests on the completed welds and document the results. Tests to include:• face bend• root bend• fracture test• nick break test1.28. Identify the function of:• weld inspection activities• quality control• quality assurance1.29. Des

    Assessment Criteria

    Key criteria assessors look for in your portfolio

    • Identify health and safety roles and procedures.
    • Describe TAG welding equipment and parameters.
    • Select and prepare materials and joints correctly.
    • Produce welds in overhead position meeting standards.
    • Carry out destructive tests and document results.

    Assessment Guidance

    Guidance for achieving higher grades

    • 💡Always check gas flow and electrode condition.
    • 💡Practise overhead welding technique.
    • 💡Record test results accurately for analysis.
    • 💡In practical assessments, always set up your workstation methodically: check gas flow, wire feed, and earth clamp before starting. Examiners award marks for preparation and safety awareness, not just the final weld.
    • 💡When answering theory questions, use specific terminology from the syllabus (e.g., 'heat-affected zone', 'dilution', 'penetration'). This demonstrates depth of knowledge and can push you into higher mark bands.
    • 💡For defect identification questions, describe both the cause and the remedy. For example, 'Porosity is caused by gas entrapment; reduce travel speed and check gas flow rate.' This shows a holistic understanding.

    Common Mistakes

    Common errors to avoid in your coursework

    • Incorrect electrode preparation for AC/DC.
    • Poor gas flow settings leading to contamination.
    • Inadequate distortion control measures.
    • Misconception: 'MIG welding is always easier than TIG welding.' Correction: While MIG is faster and more forgiving on dirty materials, TIG offers greater control and is essential for thin materials or aesthetic welds. Each process has its own challenges.
    • Misconception: 'A visually good weld is always a strong weld.' Correction: Appearance can be deceiving; internal defects like lack of fusion or porosity may not be visible. Non-destructive testing (e.g., X-ray, ultrasonic) is often required to verify strength.
    • Misconception: 'You don't need to follow a welding procedure specification (WPS) if you're experienced.' Correction: WPS ensures consistency and compliance with standards. Even experienced welders must adhere to it to guarantee quality and safety.

    Frequently Asked Questions

    Common questions students ask about this topic

    Before You Start

    Prior knowledge that will help with this topic

    • •Basic understanding of engineering materials (e.g., properties of metals, thermal conductivity).
    • •Familiarity with workshop safety practices and use of hand tools.
    • •Ability to read simple engineering drawings and interpret basic symbols.

    Key Terminology

    Essential terms to know

    • 1.1. Identify the roles of various organisations involved with Health and safety in the workplace, to include:• Health and Safety Executive (HSE)• Environmental Health• Local Authorities1.2. Identify the roles of various individuals involved with Health and Safety in the workplace, to include:• Company safety officers• Company safety representatives• Environmental health officers• HSE inspectors1.3. Identify the purpose and typical contents of an organisations Health and Safety Policy1.4. Describe the purpose of a risk assessment, to include:• who should carry out risk assessments• when to carry out a risk assessment• identification of the 5 steps of risk assessment1.5. Identify the precautions to be taken when working in high risk areas, to include:• risk assessments• permits to work• high/low temperature working conditions• lock off systems• isolation of equipment1.6. Describe the control and safe removal of welding fumes and gases created during the welding process, to include:• natural extraction• local extraction• PPE and specialist breathing equipment1.7. Describe the hazards associated when using the TAG welding process, to include:• arc radiation• using high frequency• production of phosgene gas1.8. Identify the power sources used in TAG welding1.9. Identify the type of welding current (AC/DC) and polarity to be used when welding:• low carbon steel• stainless steel• aluminium1.10. Describe the application and use of equipment used in the TAG welding process, to include:• high frequency unit• current control foot pedal• gas pressure regulator• gas flow meter• gas lens1.11. Describe the importance of correct storage conditions for tungsten electrodes and filler wires, to include:• location• ventilation• contamination• labelling 1.12. Identify the range of different alloying elements added to tungsten electrodes1.13. Identify the electrode (tip) preparation required when using an AC or DC welding current1.14. Identify the content and application of a range of filler wires used in the TAG welding process1.15. Describe the effects of using damaged tungsten electrodes and filler wires1.16. Identify the range and application of shielding gases used in the TAG welding process1.17. Identify and select the welding parameters to be used when welding low carbon steel, stainless steel or aluminium in the overhead welding position (PE), to include:• welding voltage• slope in/slope out control• torch slope and tilt angles• high frequency• speed of travel• pre/post gas flow• shielding gas flow rate (LPM)1.18. Describe the application and function of gas backing /purging1.19. Identify suitable welding preparations for the type of joint and material thickness being welded, to include:• included angle• angle of bevel• root face dimension• root gap dimension1.20. Describe the advantages and limitations of the methods listed that are used to produce suitable welding preparations on materials, to include:• thermal methods• mechanical (chip forming)• shearing• bevelling machines• abrasive methods1.21. Identify the main types of distortion found in completed welded joints, to include:• longitudinal• transverse• angular1.22. Identify the main causes of distortion in welded joints1.23. Identify methods used to control distortion in welded joints1.24. Describe the significance of residual stress found in welded joints1.25. Identify appropriate safety checks on the welding equipment prior to use1.26. Select suitable welding parameters to enable the listed joints to be welded by the TAG welding process on one material type to cover, low carbon steel, stainless steel or aluminium in a thickness range of between 1.6 mm to 3 mm.• tee fillet (PE)• butt (PE)• open outside corner (PE)• lap joint (PE)1.27. Carry out destructive tests on the completed welds and document the results. Tests to include:• face bend• root bend• fracture test• nick break test1.28. Identify the function of:• weld inspection activities• quality control• quality assurance1.29. Des

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