Carry out motor vehicle body metal active gas (MAG) welding operations

Business Sectors (Suites): Coachbuilding
Developed by: IMI
Approved on: 30 Mar 2023


This unit is about joining materials safely, correctly and effectively using metal active gas (MAG) welding techniques and procedures.

Welding involves the melting of the parent metal (steel) which fuses with the filler metal - a total fusion process.

Performance criteria

You must be able to:

P1 use the appropriate personal protective equipment (PPE) when carrying out MAG welding operations 
P2 protect the vehicle and its contents effectively when carrying out MAG welding operations 
P3 prepare material and align to enable suitable join to be achieved, ensuring mating flanges are treated following manufacturers' procedures before joining 
P4 select, set up and use the correct tools and equipment for carrying out MAG welding operations 
P5 ensure that the tools, equipment and PPE you require are in a safe working condition 
P6 set up your equipment to carry out MAG welding operations checking:

P6.1 suitability of gas / filler wire and size for material to be joined 
P6.2 parameters are set correctly 
P6.3 consumables are correct 
P6.4 feed rollers and welding tip 
P7 carry out MAG welding operations following: 

P7.1 recognised researched repair methods 
P7.2 test procedures, including providing test coupons on equivalent material in accordance with British Standards 
P7.3 manufacturers processes, methods and procedures 
P7.4 your workplace procedures 
P7.5 health, safety and legal requirements 
P8 avoid damaging other components, units, panels and surfaces on the vehicle and the surrounding work area 
P9 recognise when your weld is not forming correctly and what action needs to be taken 
P10 inspect and assess MAG weld quality in accordance with British Standards and manufacturers specification 
P11 check integrity of weld and record the type of weld achieved on the appropriate paperwork 
P12 ensure test pieces are recorded and stored 
P13 dress the joint area without reducing material thickness and protect the repaired area to inhibit corrosion where applicable 
P14 clean and store PPE and equipment in appropriate manner 
P15 promptly report any additional faults you notice during the course of your work to the relevant person(s)  
P16 promptly report any delays in completing your work to the relevant person(s)  
P17 carry out MAG welding operations within the agreed timescale 
P18 complete work records accurately, in the format required and promptly pass them to the relevant person(s)

Knowledge and Understanding

You need to know and understand:

K1 the health, safety and legal requirements relating to the joining of materials using MAG welding techniques 
K2 your workplace procedures for: 

K2.1 the referral of problems 
K2.2 reporting of delays to the completion of work 
K2.3 completion of work records 
K3 the work that needs to be done and the standard required 
K4 the requirements for protecting the vehicle and contents from damage before, during and after the joining of materials using MAG welding techniques 
K5 the importance of selecting, using and maintaining the appropriate PPE when joining materials using MAG welding techniques 
K6 how to find, interpret and use sources of information applicable to the joining of materials using MAG welding techniques and the implications of not fully understanding the repair methods presented
K7 how to select, check, maintain and set up all of the tools and equipment required to correctly join materials using MAG welding techniques 
K8 the different types of welding processes, techniques and joints used for the joining of materials when using MAG welding techniques 
K9 the correct surface preparation methods to ensure a good MAG weld is achieved and the reasons why surface preparation is important 
K10 the faults and defects that can occur when carrying out MAG welding and the common causes of these faults 
K11 the need for correct alignment of materials and the methods used to achieve this 
K12 the types of quality control checks that can be used to ensure correct joining of materials 
K13 how to inspect and assess MAG welding in accordance with British Standards 
K14 when MAG welding should be used to join materials 
K15 the difference between MAG welding techniques and other welding methods 
K16 the different types of joint that can be used to join materials using MAG welding, including: 

K16.1 lap plug 
K16.2 lap seam 
K16.3 butt joint 
K16.4 fillet joint
K17 the implications of electro-magnetic fields and the effects on medical devices
K18 the hazards of inhaling welding fumes 


All of the items listed below form part of this National Occupational Standard.

1. Personal protective equipment (PPE) for metal active gas (MAG) welding operations includes: 

1.1. face mask with appropriate eye protection 
1.2. protective/flame retardant coveralls 
1.3. protective/flame retardant gauntlets 
1.4. steel toe cap boots 
1.5. appropriate vehicle protection 
1.6. appropriate protection for others in the workshop 
1.7. appropriate fume mask

2. Tools and equipment are: 

2.1. workshop equipment 
2.2. generic hand tools 
2.3. manufacturer's specified and specialist tools
2.4. fume extraction equipment

Scope Performance

Scope Knowledge





Links To Other NOS

External Links

Version Number


Indicative Review Date

30 Mar 2026





Originating Organisation


Original URN


Relevant Occupations

Body Repair and Alignment Technician (Automotive), Body Repair Technician (Automotive), Engineering, Vehicle Trades, Coachbuilder

SOC Code



Motor; vehicle; body; MAG; welding; operations;