Skip navigation

Using semi-automatic MIG or MAG welding equipment

Level 1
Credit Value
Guided Learning Hours
The aim of this unit is to illustrate the skills, knowledge and understanding required to confirm competence in Using semi-automatic MIG or MAG welding equipment within the relevant sector of industry.

Learning Outcomes Assessment Criteria
The Learner Will The Learner Can
1 Use semi-automatic MIG or MAG welding equipment.
  • 1.1 - Work safely at all times, complying with health and safety legislation, regulations and other relevant guidelines.
  • 1.2 -  Prepare for the MIG, MAG or flux cored-wire welding process, to include carrying out all of the following:
    • adhere to procedures or systems in place for risk assessment, COSHH, personal protective equipment (PPE) and other relevant safety regulations
    • check the condition and security of welding leads/cables, hoses, shielding gas supply and wire feed mechanisms
    • set and adjust the welding conditions/parameters, in accordance with the welding procedure specification
    • prepare the work area for the welding activities (such as positioning welding screens and fume extraction)
    • prepare the materials and joint in readiness for welding (such as cleaning of joint faces, grinding weld preparations, setting up the joint, supporting the joint).
  • 1.3 - Obtain and prepare the appropriate welding equipment and welding consumables.
  • 1.4 - Use manual/semi-automatic welding and related equipment, to include one of the following:
    • MIG
    • MAG
    • other flux-cored wire welding equipment
  • 1.5 - Use consumables appropriate to the material and application, to include the following:
    One of the following wire types:
    • solid wire
    • cored wire
    Plus one of the following types of shielding gas:
    • inert
    • active
  • 1.6 - Prepare and support the joint, using the appropriate methods.
  • 1.7 - Tack weld the joint at appropriate intervals, and check the joint for accuracy before final welding.
  • 1.8 - Weld the joint to the required quality, dimensions and profile specified.
  • 1.9 - Produce two of the following welded joints of at least 150mm long, by single or multi-run (as appropriate), with at least one stop and start included:
    • fillet lap joints
    • Tee fillet joints
    • corner joints
    • butt joints
  • 1.10 - Produce joints in one of the following types of material:
    • carbon steel
    • stainless steel
    • aluminium
  • 1.11 - Produce welded joints in one of the following forms of material:
    • plate
    • section
    • sheet (less than 3mm)
    • pipe/tube
    • other forms
  • 1.12 - Weld joints in good access situations in one of the following BS EN ISO 6947 positions:
    • Flat (PA)
    • Horizontal vertical (PB)
    • Horizontal (PC)
    • Vertical upwards (PF)
    • Vertical downwards (PG)
  • 1.13 - Check that the welded joint conforms to the specification, by checking all of the following:
    • dimensional accuracy
    • alignment/squareness
    • size and profile of weld
    • number of runs
  • 1.14 - Produce welded joints which meet all of the following: (with reference to BS 4872 Part 1 Weld test requirements)
    • welds meet the required dimensional accuracy
    • fillet welds are equal in leg length and slightly convex in profile, with the size of the fillet equivalent to the thickness of the material welded
    • the welds are adequately fused, and there is minimal undercut, overlap and surface inclusions
    • joins at stop/start positions merge smoothly, with no pronounced hump or crater in the weld surface
    • tack welds are blended in to form part of the finished weld, without excessive hump
    • the weld surface is free from cracks and substantially free from porosity, shrinkage cavities and trapped slag
    • the weld surface and adjacent parent metal is substantially free from arcing or chipping marks.
  • 1.15 - Report any difficulties or problems that may arise with the welding activities, and carry out any agreed actions.
  • 1.16 - Shut down the equipment to a safe condition on conclusion of the welding activities.
  • 1.17 - Leave the work area in a safe and tidy condition on completion of the welding activities.
2 Know how to use semi-automatic MIG or MAG welding equipment.
  • 2.1 - State the safe working practices and procedures to be followed when preparing and using MIG, MAG or flux cored wire arc welding equipment (such as general workshop safety; appropriate personal protective equipment (PPE); fire prevention; protecting other workers from the effects of the welding arc; safety in enclosed/confined spaces; fume extraction/control).
  • 2.2 - State the hazards associated with using MIG, MAG or flux cored-wire arc welding (such as live electrical components; poor earthing; the electric arc; fumes and gases; spatter; hot slag and metal; grinding and mechanical metal/slag removal; elevated working; enclosed spaces; slips, trips and falls), and how they can be minimised.
  • 2.3 - State the personal protective equipment (PPE) to be worn for the welding activities (such as correctly fitting overalls; leather aprons, welding gloves/gauntlets; safety boots; head/eye shield with correct shade of filter).
  • 2.4 - State the correct handling and storage of gas cylinders (such as manual handling and use of cylinder trolley, leak detection procedures, relevant BCGA codes of practice, cylinder identification, gas pressures, cylinder and equipment safety features).
  • 2.5 - Describe how to use and extract information from engineering drawings and related specifications (to include symbols and conventions to appropriate BS or ISO standards) in relation to work undertaken.
  • 2.6 - State the major parts of the welding equipment, and their function.
  • 2.7 - Describe types, selection and application of electrode wires (such as solid and cored).
  • 2.8 - Describe reasons for using shielding gases, and the types and application of the various gases.
  • 2.9 - Describe gas pressures and flow rates (in relation to the type of material being welded).
  • 2.10 - State the types of welded joints to be produced (such as lap joints, corner joints, tee joints and butt welds).
  • 2.11 - Describe terminology used for the appropriate welding positions.
  • 2.12 - Describe how to prepare the materials in readiness for the welding activity (such as ensuring that the material is free from excessive surface contamination (such as rust, scale, paint, oil/grease and moisture); ensuring that edges to be welded are correctly prepared (such as made flat, square or bevelled).
  • 2.13 - Describe how to set up and restrain the joint, and the tools and techniques that are used (such as the use of jigs and fixtures, restraining devices (such as clamps and weights/blocks); setting up the joint in the correct position and alignment).
  • 2.14 - Describe tack welding size and spacing (in relation to material thickness).
  • 2.15 - State the techniques of operating the welding equipment to produce a range of joints in the various joint positions (such as fine adjustment of parameters; correct manipulation of the welding gun; blending in stops/starts and tack welds).
  • 2.16 - Describe methods/modes of metal transfer and their uses (such as dip, globular, free flight, spray and pulsed).
  • 2.17 - Describe how to close down the welding equipment safely and correctly.
  • 2.18 - Describe problems that can occur with the welding activities (such as causes of distortion and methods of control; effects of welding on materials and sources of weld defects), and how these can be overcome.
  • 2.19 - Describe how to check the welded joints for uniformity, alignment, position and weld size and profile.
  • 2.20 - Describe when to act on their own initiative and when to seek help and advice from others.
  • 2.21 - State the importance of leaving the work area in a safe and clean condition on completion of welding activities (such as isolation of electrical supplies, safely storing equipment and consumables, removing and disposing of waste).
Assessment guidance and/or requirements
This unit must be assessed in a work environment and must be assessed in accordance with the ‘Common Requirements for National Vocational Qualifications (NVQ) in which can be downloaded from Semta’s website or requested via assessment requirements have been published by Semta. These additional assessment requirements are set down in Semta’s PEO NVQ unit assessment strategy which can be downloaded from Semta’s website or requested via