Health, safety and accident prevention
General information
The Health & Safety at Work Act, 1974, places a duty on the
employer to provide premises, plant and systems of work which are, so far as it
is reasonably practical, safe and without risk to health. It also charges
employees to take reasonable care for their own health and safety and for that
of others.
In this article, the general hazards which may arise when carrying out
welding and related operations, are identified. In subsequent articles,
guidelines will be given on the principal health and safety considerations for
each welding process.
Regulations and codes of practice
The Health and Safety at Work Act, 1974, requires that the risk to workers of
injury or ill health due to work activities should be minimised and there are
many national and international Regulations, approved Codes of Practice and
Standards covering the safe operation of welding and cutting systems. Those of
more direct interest to welders and welding engineers are listed at the end of
the article. In the UK, particular attention should be given to the Health and
Safety Executive (HSE) publications.
Safe assembly
Although welding and cutting operations require special considerations,
personnel should be aware of the general health and safety requirements of
related fabrication activities. Safe places and systems of work include handling
and housekeeping.
The
wrong and right way to carry out arc welding processes
Safe control of arc welding
Arc processes produce fumes which contaminate the atmosphere surrounding the
work. Precautions must be taken to eliminate the risk of electric shock. Actions
to ensure safe practice and accident avoidance will be presented in a subsequent
issue.
Personal protection
Fume
Firstly, can exposure can be prevented by eliminating the generation of
welding fumes altogether? If not, fume will have to be controlled at source,
perhaps by local ventilation. Respiratory equipment should not be used until all
other possibilities have been eliminated. In general, respiratory protective
equipment is used only as an interim measure but there will be circumstances
where, in addition to ventilation measures, personal protection may be
necessary.
Arc radiation
The arc can generate three types of radiation; ultra-violet, visible and
infra red (heat) radiation which can be injurious in the following ways:
- ultra-violet: damage to skin and eyes(inflammation of the
cornea and cataracts)
- visible light: dazzle eyes and impair vision
- infra-red: damage skin and eyes
Radiation may be direct or reflected from shiny or other reflective surfaces.
Safe practice and accident avoidance
- Protect face and eyes using a suitable welding shield equipped with eye
protection filter
- Protect the body by wearing suitable clothing
- Protect persons in the vicinity of the arc by means of non-reflective
curtains or screens
Fire and explosion hazards
Fire
There is an inherent hazard associated with gas processes.
Additionally, both flames and arcs in welding and cutting may create a fire
hazard,. When fighting a fire, the appropriate fire extinguisher for the type of
material must be used. Class C fires, for example those involving flammable
gases such as acetylene, are best extinguished by cutting off the gas supply.
Water and foam extinguishers should not be used on fires near to live electrical
equipment.
Safe practice and accident avoidance
- Remove flammable material from the welding area
- Cover remaining flammable material with fire resistant material
- Before welding, check that the appropriate fire fighting equipment is at
hand
- After welding, observe surrounding area of the work for an adequate period
of time (suggest about one hour)
Explosion
There is danger of explosion when welding a container which previously
contained explosive or flammable substances; explosive material can be trapped
in grooves, seams, riveted joints or behind scale.
Safe practice and accident avoidance
Before welding, the following
actions should be carried out:
- Remove explosive material by steaming or boiling out
- If the explosive material cannot be completely removed, fill the container
with water, an inert gas or pass steam through it
Welding in confined spaces
Special care should be taken in case toxic
fumes or gases build up. In gas shielded welding operations, there may be a
danger from asphyxiating because of oxygen deficiency. A suitably qualified
person should assess the risk, determine the steps required to make the job safe
and recommend precautions to be taken during the welding operation itself.
Safe practice and accident avoidance
- Ensure adequate ventilation and, if necessary, use personal protection
- Ensure that any used vessel does not contain flammable, poisonous or
explosive material
- Ensure gas cylinders are not taken into the enclosed space
- Check equipment for gas leaks
- Ensure trained personnel are in attendance to deal with any emergency
- Check by rehearsal that the worker can be rescued, should an emergency
arise
- At the end of work periods, shut off all gas supply valves and withdraw
hoses and equipment
Awareness of welding environments
Noise
As a general guideline, wherever it is difficult to carry on a
conversation, it is likely the noise level is unacceptable. HSE recommendations
are that when the noise reaches 85dB(A), employers are required to offer hearing
protection to their employees. As continuous exposure for 8 hours or more to a
noise level at or above 90dB(A) is injurious, hearing protection is mandatory
when this level is reached. Higher levels can be tolerated for short periods but
impulsive or peak noise in excess of 140 dB should not, where practicable, be
exceeded.
As damaging noise levels can be generated from some welding processes and
allied activities, welders will usually need hearing protection. For example,
hand grinding may emit noise levels of the order 108dB(A).
Safe practice and accident avoidance
If noisy equipment or processes
cannot be avoided, one or more of the following alternatives may apply:
- Insulate the noise source as far as possible by fitting silencers or sound
proof enclosures
- Insulate the operator from the noise source by wearing suitable ear
protection
- Where practicable, do not exceed impulsive noise levels in excess of 140
dB
Vibration
Portable tools which produce excessive vibration, may cause damage to the
hands, often called 'white finger' (Raynaud's phenomenon). As the hazard is
particularly acute with tools such as chipping hammers which rely on impact,
their use must be minimised.
Safe practice and accident avoidance
- Avoid or limit the use of equipment with excessive vibration
- Keep the hands warm
- Avoid an excessively strong grip when holding the tool
Designation of hazardous areas
It may be necessary to restrict entry to the work area to authorised persons
wearing suitable protection. Warning signs will be required for the following
hazards:
- For welding and cutting processes, where the arc is exposed, the warning
for eye protection should refer to the hazard of arc radiation
- 'Ear Protection Areas' where 8 hours exposure to noise levels is at, or
above, 90 dB(A).
Further information
The following are useful standards and codes of practice relating to health
and safety in welding and allied processes:
HSE publications
EH 55,1990, The control of exposure to fume from
welding and allied processes
HS(G) 53, 1990, Respiratory protective
equipment: a practical guide to users
HS(G) 56, 1990, Noise at work, noise
assessment, information and control
HS(G) 118, 1995, Electrical safety in
arc welding
British standards
BSEN 169: 1992 Personal eye protection equipment used
in welding and similar operations
BSEN 470-1:1995 Protective clothing for
welders
The information was prepared in collaboration with Roger Sykes, Health &
Safety Executive, Newcastle upon Tyne.
Copyright by TWI, 1999
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