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Welding and the Hazards of Confined Spaces


  • A confined space can be any space of an enclosed nature, where there is a risk of death or serious injury. This could be from the rapid build-up of hazardous substances, or from lack of oxygen.

  • Less obvious confined spaces include open-topped chambers, ductwork and poorly-ventilated rooms.

  • Welding fume (which includes irritating gases such as oxides of nitrogen and ozone) may cause respiratory irritation and metal fume fever. It can also increase susceptibility to pneumonia. In the longer term, it can lead to serious lung diseases including chronic obstructive pulmonary disease (COPD), which used to be called chronic bronchitis, and emphysema, occupational asthma and cancer.

  • Shielding gases (such as argon, helium and nitrogen, or argon-based mixtures containing carbon dioxide, oxygen or both) can cause asphyxiation (suffocation from lack of oxygen), usually resulting from accumulation of the gases in confined spaces.

  • Fume and dust from allied processes, e.g. flame and arc cutting, blasting and post-weld dressing, can cause lung disease.

  • Abrasive blasting produces a great deal of dust that includes metals and metal oxides.

  • Each situation is different. The hazard varies and is dependent on the process, e.g. the welding consumable, the base metal, surface coatings or contaminants, and where the task is done.

  • Welding can act as a source of ignition for flammable gases, vapours (e.g. from residues), dusts, plastics and many other materials which may burn, leading to a fire or explosion.

  • Welding on the outside of a confined space can easily ignite materials in contact with the metal on the inside.

Access to work area

Allow access to authorised and appropriately trained people only and, if possible, avoid entry to undertake the task. In the event that entry is unavoidable, ensure there is a safe system of work and emergency arrangements in place before work starts.

Equipment and procedures

Safe system of work

  • Ensure good air movement and mixing by a suitable means of forced ventilation.

  • If required, wear breathing apparatus. Workers should check that it is working properly.

  • Ensure that whoever develops the safe system of work is competent.

  • Identify the precautions that will reduce the risk. A permit-to-work is needed.

  • Ensure that workers selected are competent and physically able to do the task.

  • Equipment must be suitable for use in a confined space.

  • Isolate mechanical and electrical equipment that could cause harm if turned on.

  • Ensure safe access and egress from the confined space, access routes and hatches are large enough, and rescue harnesses are suitable. Caution: Never use fuelled engines in confined spaces or where there is poor ventilation. Carbon monoxide gas can cause asphyxia and death.

  • Check the concentration of oxygen in the air before entry, and monitor the air continuously during the procedure.

  • Have a competent person perform toxic and flammable gas/vapour tests.

  • Provide personal gas monitors for the gases that may be encountered in the confined space. Caution: Never try to ‘sweeten’ the air with oxygen. This increases the fire or explosion risk.

  • Ensure alarms are in place and that they were audible when last tested.

  • Use non-sparking tools or flameproof lighting for the task.

  • Ensure that people inside the space can communicate with those outside.

  • Where multiple entry occurs, ensure workers are checked in and out.

Emergency procedures

  • When things go wrong, you need effective arrangements for rapid rescue of those in danger.

  • A specific plan is needed for an identified confined space, the risks, the number of people at work, and the likely nature of any emergency rescue.

  • Critical requirements include defining:

    • means for communication between workers and rescuers;

    • the rescuers’ capabilities and training;

    • the rescue and resuscitation equipment needs;

    • any emergency shut-down of plant or equipment.

  • Train everyone involved. Hold practice sessions and modify your procedures to improve the performance. Caution: Reducing flames can produce carbon monoxide gas, which can cause asphyxia and death.

Respiratory protective equipment (RPE)

  • Provide air-fed ‘CE’-marked RPE with an Assigned Protection Factor (APF) of at least 40, or cylinder breathing apparatus (BA) if oxygen levels could be depleted. Wearers must be medically fit to wear BA.

  • Make suitable arrangements for maintenance, storage and replacement of RPE.

  • Air supplied to BA should meet minimum quality requirements, in line with the latest British Standard.

  • Tell workers to check RPE is working properly before every use.

  • Keep RPE clean and store it in a clean place.

Personal protective equipment (PPE)

  • Ask your supplier to advise on suitable PPE.

  • Provide and ensure that workers use a welding visor, flame-resistant overalls and protective gloves.

  • Ensure that all items of PPE are compatible.

  • Use a contract laundry or a suitable equivalent to wash work clothing. Don’t allow workers to do this at home.

  • Make suitable arrangements for maintenance, storage and replacement of PPE.

  • Keep any PPE cleaned and replace at recommended intervals. Personal decontamination

  • Provide warm water, mild skin cleansers, and soft paper or fabric towels for drying. Avoid abrasive cleansers.

  • Provide pre-work skin creams, which will make it easier to wash dirt from the skin.

  • Provide after-work creams to replenish skin oils. Caution: ‘Barrier creams’ are not ‘liquid gloves’ and do not provide a full barrier.

Maintenance, examination and testing

  • Keep all equipment used for the task in effective working order. Maintain it as advised by the supplier or installer.

  • Check for signs of damage to equipment before starting work.

  • Have equipment thoroughly examined and tested against its performance standard at suitable intervals.

  • Look for signs of damage daily. Noisy or vibrating fans can indicate a problem.

  • Get a competent ventilation engineer to examine the system thoroughly and test its performance regularly.

  • Keep records of all examinations and tests for at least five years.

  • Review records – failure patterns show where preventive maintenance is needed.

Cleaning and housekeeping

Keep the work area clean and free of combustible materials. Caution: Never allow the use of brushes or compressed air for removing dust from skin and clothing. Avoid the use of brushes or compressed air for removing dust from surfaces or from inside machinery.

Health surveillance

Provide health surveillance for asthma where there is a reasonable likelihood that asthma may occur in your workplace.

Training and supervision

  • Tell workers that shielding gas can deplete the oxygen in the air, which can cause unconsciousness and even death.

  • Explain to workers about the health hazards from welding fume.

  • Train and supervise workers and ensure they fully understand the safe working practices detailed in the confined space risk assessment.

  • Before work begins, a competent person must assess the suitability of the workers intending to enter the confined space. The competent person may need to consider other factors, eg. concerning claustrophobia or fitness to wear breathing apparatus, and may need to seek medical advice.

  • Provide training for any work in confined spaces and specifically for:

    • the task to be carried out;

    • the working environmental conditions in the confined space;

    • working materials and tools to be used;

    • arrangements for emergency rescue.

  • Consider keeping training records.

  • Involve managers and supervisors in health and safety training.

What Can RCS Do For You

RCS's engineers will endeavour to provide you with the most effective and cost-efficient solution for welding fume extraction, fully COSSH compliant, following current HSE guidelines and your own individual requirements. Call us on +44(0)1563 546807 or click here to contact us for more information.


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