Health and Safety in Welding and Allied Processes

258 Pages·2002·4.22 MB·English

by  J. Blunt and N.C. Balchin (Auth.)

Health and Safety in
Welding and
Allied Processes
FIFTH EDITION
Jane Blunt and Nigel C Balchin
Published by Woodhead Publishing Limited, Abington Hall, Abington
Cambridge CB1 6AH, England
www.woodhead-publishing.com
Published in North America by CRC Press LLC, 2000 Corporate Blvd, NW
Boca Raton FL 33431, USA
First published 1956, Institute of Welding
Revised and enlarged, July 1963
Second edition, 1965
Third edition, 1983, The Welding Institute
Fourth edition, 1991, Abington Publishing
Fifth edition, 2002, Woodhead Publishing Limited and CRC Press LLC
© 2002, Woodhead Publishing Limited
The authors have asserted their moral rights.
This book contains information obtained from authentic and highly
regarded sources. Reprinted material is quoted with permission, and
sources are indicated. Reasonable efforts have been made to publish
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assume responsibility for the validity of all materials. Neither the authors
nor the publishers, nor anyone else associated with this publication, shall
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Introduction
This is the fifth edition of this work. It has been extensively revised
to take into account changes in technology and legislation. Every
effort has been made to include the legislative requirements of both
the United Kingdom and the United States of America in order to
make this book useful to personnel on both sides of the Atlantic.
References for each country are given throughout.
Some reorganisation of the contents has taken place, and a worked
example has been included in Appendix B to illustrate the method
of risk assessment, which is the basis for the assessment and control
of risk in the United Kingdom.
The work begins with a description of the core safety require-
ments. It then describes the special hazards found in the welding
environment – noise, radiation, fume, gases, etc, in terms of their
effects and the strategies that might be adopted to avoid them. The
central part of the book takes each major joining technology in turn,
and discusses the key hazards that are most relevant to that tech-
nology. Finally there is a chapter on testing and welding in situa-
tions of increased hazard.
The information in this book is believed to be correct at the time
of going to press. However, it must be stressed that the onus is on
employers to address the risks that exist in their own workplaces,
and to ensure that they are complying with the laws that govern
work in their own locality.
This book should be of use to welders, their managers, and to all
health and safety practitioners who have welding and similar
processes taking place in their workplace.
vii
1
Setting up the Workplace
In both the United Kingdom and the United States of America,
there is a legislative framework that assigns a very large measure
of responsibility to employers for the health and safety of their
employees. The detailed approach is slightly different and readers
need to familiarise themselves with the requirements. Where they
have doubts, they should consult the enforcing authorities for
advice:
• The Health and Safety Executive (United Kingdom)
• Occupational Safety and Health Administration (United States
of America).
The general requirements in the United Kingdom are laid down
in the Health and Safety at Work, etc, Act, 1974,1 which places a
duty on all employers to ensure as far as is reasonably practi-
cable, the health, safety and welfare of all of their employees while
they are at work. Many duties are also extended to those not in their
employment but who may be affected by the employer’s under-
taking. The Act enabled the making of Regulations, which contain
detailed specific requirements, which employers are required to
comply with. The basis upon which employers should act is
one of risk assessment – where employers must analyse the risks
associated with their work activities and implement measures to
control those risks.2 Employees are required to cooperate with their
employer’s efforts to meet the requirements of the Act and the
Regulations.
There are two useful websites where further information may be
obtained, Her Majesty’s Stationery Office,3 where the full text of all
Statutory Instruments published since 1987 is available to view and
print, and the Health and Safety Executive,4 (HSE), where there is a
great deal of advice and guidance.
3
4 Health and Safety in Welding and Allied Processes
The general requirements in the United States of America are
laid down in section 5 of the Occupational Safety and Health Act
of 1970,5which requires employers to furnish each of their employ-
ees with employment and a place of employment which are free
from recognised hazards that cause or are likely to cause death or
serious physical harm to those employees. The Act requires employ-
ers to comply with the occupational safety and health standards that
it promulgates. The Occupational Safety and Health Administration
(OSHA) maintains a website from which access can be gained to
Federal Regulations.6 Employees are required to comply with the
rules, regulations and orders that apply to them.
The net effect in both countries is that in order to ensure that the
workforce remains safe and that the requirements are met, a system
is needed to manage safety in the workplace. An efficient system
will not only meet the legislative requirements, but is also cost effec-
tive in minimising lost time through illness and injury.
The employer should set up a policy for the assurance of health
and safety and assign responsibilities for undertaking the many tasks
that will need to be carried out. The workplaces will need to be con-
structed and maintained in good order. The work equipment will
need to be fit for its purpose and properly maintained .7 Setting up
a safety committee enables worker participation and establishes
good communication. Safety rules will be needed and the workforce
will need to be trained so that they know what hazards they face,
the preventive and protective measures that are needed to avoid the
risk of injury or ill health, and how to make the best use of those
measures, including personal protective equipment if it is needed.8
An inspection programme will be needed to ensure that the mea-
sures are adequate and that tasks are being carried out as required.
In many workplaces, there will be a need for some health surveil-
lance and monitoring of key indicators.
The Workplace
First, the prescribed poster should be put up in the workplace. In the
UK, this is available from the HSE or good bookshops.9Alternatively,
the prescribed leaflet10may be distributed to every employee. In the
USA, the prescribed poster11can be downloaded from the government
website. The workplace should be in accordance with the provisions
of the Workplace Regulations,12 or in the USA, according to the
requirements of subparts D and J of 29 CFR 1910.13,14
Setting up the Workplace 5
Indoor workplaces should be kept at a reasonable temperature. A
temperature of 16 °C or above is recommended where personnel are
undertaking light work, and a minimum of 13 °C where heavy work
is undertaken. Measures may need to be taken in hot weather to
prevent people from becoming overheated.
Adequate sanitary facilities should be provided, with facilities for
washing and drying the hands. The facilities should be kept clean.
An area should be set aside, separate from the work area, where food
and drink can be consumed without contamination by substances
hazardous to health.
Walkways should be marked and kept clear. The walkways should
have surfaces that are free from holes, slippery substances and water,
to avoid slips, trips and falls. There should be railings or other
guards to prevent people from falling down stairs, shafts, etc.
Lighting
When work must be carried out in areas where insufficient daylight
is available it will be necessary to provide artificial lighting, which
will almost invariably be electric. Two cases must be covered:
normal operation and emergency lighting. General advice is given
in an HSE publication.15
Normal lighting
The information in Table 1.1 below has been selected from Table 1
of the now obsolescent British Standard16 as that most likely to be
applicable to welding activities.
The general run of welding work on mild steel plate, often with a
black surface, will be of very low contrast. Although arc welding is
an almost unique operation, in that the arc emits far more light than
Table 1.1. Illuminances and corresponding activities
Standard service Visual task Details to be seen
illuminance (lux)
Size Contrast
500 Moderately difficult Moderate Low
750 Difficult Small Low
1000 Very difficult Very small Very low
1500 Extremely difficult Extremely small Very low
6 Health and Safety in Welding and Allied Processes
any practicable artificial illumination, good general illumination
will permit the use of a lighter shade of viewing filters because the
eyes adapt to the general level of illumination by narrowing of the
pupils and the arc light has to be reduced less to match. This gives
welders a better view of the weld with less eye strain and renders
them less susceptible to dazzle by an accidental view of an arc.
Good lighting is also important to facilitate preparatory work, such
as edge preparation and assembly of components, and visual checks
after welding by the welder himself, etc. Where there is rotating
machinery (such as turntables for spraying, or lathes) the designer
of the lighting system should avoid stroboscopic effects.
The environment in a normal welding shop will require allowance
for reduction of output due to dust accumulation on luminaires
(lighting fittings) during the intervals between routine lamp replace-
ment and cleaning. It is not necessary to paint a welding shop black
to avoid reflection of ultraviolet (UV) light (see Chapter 7).
For work on site, some welding generators are available with an
outlet to power lights; as this is often of low power or of non-
standard voltage or frequency, the exact facilities required should be
checked against the specification.
For the illumination of fuel gas stores, where a leak could give rise
to an explosive atmosphere, flameproof equipment will be required
(see Chapter 4), unless it is possible to site the lighting outside the
hazard area. This may offer security advantages.
Emergency lighting
If a complete electrical power supply failure occurs after dark, emer-
gency lighting will be needed to ensure that workers are able to see
well enough to carry out such actions as the following:
1 Making safe any radiographic equipment, especially isotope
sources,
2 Shutting down all gas flames for welding cutting preheating, etc,
3 Switching off all electric welding equipment,
4 Rendering safe any equipment relying on supplies also cut off by
an electric power failure, such as water cooling, compressed air
or ventilation systems,
5 Ensuring that all crane motors are switched off and that any
suspended loads which present a hazard, will be marked if
necessary,
Setting up the Workplace 7
6 Rescuing anyone trapped, such as in a crane jib or lift,
7 Evacuating the premises in an orderly fashion, making sure that
no one is left behind.
If it is necessary to cut off the supply in the event of fire, similar
considerations will apply. Escape lighting should:
1 Indicate the escape routes clearly and unambiguously
2 Illuminate those routes that allow safe exit
3 Enable the ready location of fire alarm call points and fire fight-
ing equipment on escape routes.
On defined escape routes, 0.2lux illumination is required and 1lux
where they are not defined, that is, where they run across an
open area. Regular servicing, inspection and testing must be organ-
ised to make sure that the system will function if and when it is
required.
Housekeeping
The workplace should be kept clean and tidy. Trip hazards can be
avoided by careful siting of leads and hoses and not putting tools
down where people may walk. Tools should be put away each day.
Oily waste should be placed in metal bins. All bins should be
emptied regularly to avoid an accumulation of combustible waste.
Where personal protective equipment is provided, there should be
provision for its safe storage, and it should be put away when not
in use. Accumulations of metal dust, which are especially likely in
a thermal spray workshop, can be explosive.
Manual Handling
Many injuries are attributable to manual handling.17 Lifting tasks
should be assessed critically. Manual handling tasks that are likely
to be hazardous should be avoided where possible. Many can be
avoided by the use of suitable lifting aids, such as trolleys and sack
barrows. Where manual handling is essential, the task should be
assessed and personnel should be trained in good lifting technique.
Good practices include bending the knees rather than the back to
pick up the load, keeping the load close to the body and keeping the
back straight while making the lift using the legs. Valuable advice is
given in the Manual Handling Regulations.17
8 Health and Safety in Welding and Allied Processes
Electrical Hazards
Electricity can give rise to electric shock (which can be fatal), burns,
falls, fire and explosion. It also gives rise to electric and magnetic
fields, whose effects on the body are not yet fully understood.
Fixed wiring
Employers must set up their fixed wiring to adequate standards.18–20
Insulation prevents access to live conductors. Conductors should be
chosen that are adequate for both the intended and the foreseeable
fault currents. Devices are available to shut down equipment in the
event of a fault (e.g. fuses, residual current devices). Where equip-
ment and supplies have an earth (ground) connection, it is essential
that it is connected at all times. Work on electrical equipment must
only be carried out by competent persons, who work according to
safe practices.21
Where a workspace is very large, it is sometimes convenient to
connect different areas to different phases of the incoming supply.
Where this is the case, it is important to ensure that welders working
from different phases do not come into close proximity with one
another because this substantially increases the danger.
Electrical equipment
Welding and associated equipment needs to be maintained in a safe
condition. Equipment should be inspected to establish that it is in
good condition. In the UK there is a requirement to test insulation
and earth connections.22 Inspection can establish that there is no
damage to insulation and fittings and that there are no signs of over-
heating or other faults.
Other items of hand-held electrical equipment, such as grinders,
are vulnerable and should be checked formally at relatively frequent
intervals (say from three to six months depending on the environ-
ment in which they are being used). Larger items, such as the
welding sets, which are not moved around frequently, may be for-
mally tested at annual intervals. Testing should be carried out at
more frequent intervals if it is apparent that a significant number of
faults are being found. This testing does not remove the necessity
for the user to make checks regularly, since this is when most poten-
tially dangerous faults are discovered.
Setting up the Workplace 9
Table 1.2. Reference levels for occupational exposure
to time-varying electric (E) and magnetic (B) fields
(unperturbed rms values)
Frequency range E-field strength (Vm-1) B field (mT)
<1Hz – 2 ¥105
1–8Hz 20000 2 ¥105/f2
8–25Hz 20000 2.5 ¥104/f
0.025–0.82kHz 500/f 25/f
f is frequency, as indicated in the frequency column.
Electric and Magnetic Fields
Since electric welding processes use very large currents, magnetic
fields in the workplace can be larger than those experienced in other
occupations. Electric fields associated with welding are low. While
most medical studies have shown there is no hazard to health from
electromagnetic fields, exposure to large fields can give symptoms,
and it is prudent to minimise exposure. There are proposals for the
restriction of exposure, given in Table 1.2 above.23 The unit of mag-
netic field is the tesla (T). It is difficult to shield magnetic fields, and
therefore the normal approach to control of exposure is to avoid
entering the area of high field. Typical values from Table 1.2 indi-
cate a suggested limit of 200mT in a steady field (which is compa-
rable to the field that can be obtained from a good ceramic magnet),
falling to 0.5mT at 50Hz.
Arc welders should avoid draping the welding cable over their
shoulders or wrapping it around their body so as to avoid exposing
parts of their body to fields above the guideline figures.
Pacemakers
Pacemakers are medical devices that are implanted in some cardiac
patients to regulate their heart rhythm. Electromagnetic fields from
welding can affect pacemakers, but the precise effects depend on the
type and susceptibility of pacemaker and the cardiac condition that
it is intended to correct. Welders who are to have a pacemaker fitted
should take advice from their specialist. Most conventional welding
equipment will probably not present a great risk. However, equip-
ment that can produce strong pulses of electromagnetic radiation,
such as resistance welders may interfere both with the function of
the pacemaker and its programming. It is recommended that the