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Occupational health and safety regulations with
regard to welding and assessment of the exposure to
welding fumes and of their effect
This article presents a model for the assessment of the exposure to welding
fumes and of their effect. The model and the hazard figure calculated with
it should not be understood as an assessment in relation to occupational
medicine and toxicology but are instead intended to be described with
technical tools and, from a technical viewpoint, comparisons between
processes, materials and workplace-specific factors and, while doing so,
try to explain why a residual risk remains in the case of some welding technology work. The use of personal protective equipment (here, wearing
breathing apparatus) should be recognised as a necessary supplementary
protective measure (see TRGS 528 [1], particularly the sections with regard
to the evaluation of the hazards and to the protective measures).
1 Introduction
It is known from literature sources that soldering
processes were already used for the joining of noble metals
in the ancient world. The industrial revolution in the 19th
century was the starting point for a systematic development of welding technologies. It is the time when the generation of energy transfer media and their use for the
manufacturing of certain products become possible. Keywords in this context are: electrical energy (arcing processes) and chemical energy (in the form of acetylene).
Some examples
In 1885, the carbon arc was used by the Russian Benardos for the fusion of metals and alloys, missing material
being replaced by currentless filler wire. In 1889, Zerener
registered a process for patent where the arc burns between two carbon electrodes. In 1890, the Russian Slawjanow registered a patent; he used the filler wire itself as
the arc transfer medium and thus combined electrode
and filler wire. In 1889, the pressure-reducing regulator
was patented by Dräger. In 1892, the large-scale industrial
production of calcium carbide was started.
The time needed for the development of the arc technology was significantly longer. We know of first „welding
trials“ as early as in 1792 but the possibility to develop
welding processes only arose with the generation of electric current on a large scale (end of the 19th century).
Since the middle of the 20th century, an increase in
the number of welding processes and materials can be
observed. In the eighties, the automated use of processes
was increased and laser welding established in industry.
In 2004, about 70% of the fusion welding processes used
were metal gas welding processes, as related to the deposited weld metal.
With progressing development of welding current
sources, the welding arc could increasingly be influenced
by electronic control. Firstly, high-power types of gasshielded metal arc welding are developed, the wire feed
rates of which are up to three times higher than those
commonly used. Different gas mixtures of argon, carbon
60
THE AUTHOR
Dr.-Ing. Vilia Elena Spiegel-Ciobanu is Chairman of the Section „Hazardous Substances in Welding and Allied Processes“ in the BG Expert Committee „Metal and Surface Treatment“ (FAMO) of
the German Social Accident Insurance (DGUV),
German Social Accident Insurance Institution for
the Woodworking and Metalworking Industries
(BGHM).
dioxide, helium and oxygen support the new processes
and process types. Latest developments model the arc individually for the relevant welding task or position.
The prospect for further development of welding technology seems to be that conventional welding processes,
especially gas-shielded arc welding and resistance welding, will continue to be the dominant types of application
but that special welding processes will increasingly become important.
Parallel to the development of the processes, the materials to be treated are developed further and refined.
BGI 616 contains more information in this context. Mechanisation and automation are promoted in order to
achieve higher productivity, higher capacities and higher
quality.
In accordance with EN 14610, the most widespread
metal welding processes can be roughly divided with respect to the type of energy transfer medium into autogenous processes (gas fusion welding, energy transfer medium: gas), arc processes (gas-shielded metal arc welding,
tungsten inert gas and plasma welding, energy transfer
medium: electric gas discharge), resistance processes
(resistance pressure welding and resistance fusion welding, energy transfer medium: electric current) and beam
processes (laser beam welding and electron beam welding, energy transfer medium: radiation). Additional
processes used are friction welding (energy transfer medium: mass which is moved), fusion welding with liquid
heat transfer (energy transfer medium: liquid) and a
range of pressure welding processes (energy transfer
medium: mass which is moved and undefined energy
transfer medium).
There are also great differences between the process
groups of welding, thermal cutting, thermal spraying and
soldering/brazing due to process conditions. These two
different categorisations must also be considered when
considering the connected hazards. Different hazards occur, e.g. optical radiation, electric current, hazardous substances etc., and the effects of these are different as a function of the process and the material, from both qualitative
and quantitative points of view.
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2 Hazard assessment
Fig. 1 • Welding –
Development
of occupational
health and
safety (example
Germany).
[2...4]
Mandatory limit values serving as the upper limit for
the relevant exposures to hazardous substances are of
special importance for hazard evaluation [6]. Concerning
hazardous substances in welding and allied processes,
there is no special welding fume limit value at present.
For the assessment of the exposure to welding fumes (particulate substances), the A fraction of dust of 3 mg/m³ as
the upper limit is of assistance. In addition, the substancespecific limit values for key and main components shall
be considered, e.g. AGW (workplace exposure limits, OEL)
for Mn and Cu (as MnO and CuO). Carcinogenic substances are excluded from this (risk-related values in
preparation). For these substances, the minimisation order according to GefStoffV (German Hazardous Substances Ordinance) is prevalent.
The main objective is the hazard-oriented specification of protective measures on the basis of information
collection and knowledge about workplace exposure limits (OEL) and the classification of hazardous substances.
The level of exposure of the welder to hazardous substances mainly depends on the process used (e.g. gasshielded metal arc welding) and its parameters (e.g. current, voltage etc.), the process types (e.g. pulsed arc) and
the materials (e.g. high-alloyed steels), the auxiliary materials/consumables used (e.g. shielding gases) and the
surface condition of the materials (e.g. oiled or coated).
These factors directly influence the level of the emission
rate (in mg/s) and thus also the level of concentration (in
mg/m³) at the workplace (in the breathing zone of the
welder or stationary in the room).
In addition, workplace-specific factors like the ventilation situation, the head/body position of the welder and
the room volume influence the level of hazardous substance concentration in the breathing zone of the welder
and partially also the room pollution. The chemical composition of the utilised materials and consumables (e.g.
rod wire/filler wire and shielding gases) is responsible for
the chemical composition of the welding fumes and gases
generated. The toxicity of the individual components and
also their synergetic effect must be considered in the hazard evaluation by effect-specific factors.
For medium, high and very high emission rates without ventilation measures, hazardous substance concentrations occur in the breathing zone of the welder exceed
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the limit values many times over. For low emission rates,
it is known by experience that the hazardous substance
concentrations in the breathing zone of the welders are
in the range of the limit values or slightly below. Therefore,
priority shall be given to:
• selection of low-emission processes (as far as technically feasible);
• selection of low-emission materials (as far as technically feasible);
• optimum solutions for ventilation technology.
Other hazards during welding are e.g.:
Electrical hazard
For an increased electrical hazard, especially in confined spaces, dangers result from electric current. Protection of the arc welder against electrical hazards caused
by welding equipment (current sources, torches, electrode
holders and other work equipment) covers their construction, installation and use (safe operating state, correct installation and safe use).
Thermal hazard
The heat of the arc also creates metal and slag spilling,
hot electrodes and hot torches. This gives rise to the hazard
of burning. Fire-resistant protective clothing and appropriate hearing protection are required for protection.
Physical hazards by optical radiation and noise
There is also a hazard due to e.g. optical radiation like
arc radiation or – less intensive by far but nevertheless
hazardous – light radiation from the oxyacetylene flame
and the welding bath and to noise. Personal protective
equipment is required: Eye protection with the appropriate protection class, work and protective clothing, respiratory protective equipment, hearing protectors and skin
protection.
Fire and explosion hazards
Ignition sources (arc, thermal conduction and sparks/flying sparks during welding) often cause fires and explosions. Recommended preventive measures are: Covering,
sealing, fire watchers, provision of fire extinguishers etc.).
These dangers and related hazards shall be taken into
account appropriately. Suitable protective measures shall
be selected and effected [7;8].
3 Assessment of exposure to welding fumes
and their effect on the welder
During welding, cutting and allied processes, different
amounts of gaseous or particulate substances are generated as a function of the processes and materials used.
The particulate substances mainly have a particle size
(aerodynamic diameter) of below 1 µm, are respirable
and are called „welding fumes“ in practice. The chemical
composition of the particulate substances primarily depends on the chemical composition of the materials used
(filler/parent metals).
The quantity and composition of gaseous substances,
in contrast, are mainly based on surface impurities (oil and
Welding and Cutting 11 (2012) No. 1
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Table 1 • Process-specific hazard figures (GZ)E.
Table 2 • Effect-specific hazard figures (GZ)W.
Table 3 • Correlation between the process-specific and effect-specific hazard figures
(GZ)E and (GZ)W (the figures – the result of the multiplication E x W – refer to
a percentage of 100% of toxic or carcinogenic substances in the welding fume).
Table 4 • Factors for ventilation and spatial conditions (for particulate substances;
with capture: with technical ventilation measures; without capture: without technical
ventilation measures; confined space*: spatial volume smaller than 100 m³).
grease) and coatings. As the welding fumes have very complex and varying compositions, workplace monitoring is
mostly based on key components. The complexity of the
welding fumes also entails the difficulty to evaluate diseases
in welders from an occupational medical point of view.
Thus, e.g. the causes of diseases of welders are not
sufficiently clear. The causal connection between exposure
to welding fumes and a disease of e.g. the respiratory
tract/lung often can only be found with great difficulties.
The reason lies in the difficulties occurring, on the one
hand, during technical identification of the data and, on
the other hand, during occupational medical assessment
– due to insufficient data about toxicological effects.
Experience showed that the collection of occupational
anamnesis data which occurred during assessments within the German framework of the BK (occupational disease)
procedures often presented difficulties, as the general
62
conditions – materials used, auxiliary means etc. – are in
most cases difficult to identify in retrospect.
For an improvement of the prevention and the identification of causes of diseases in welders, the following
procedure is suggested:
• Data identification within the framework of a wellfounded occupational anamnesis is supported by an
occupational anamnesis sheet encompassing several
pages („Informationsermittlung für die Gefährdungsbeurteilung/Arbeitsanamnesebogen“,
http://www.bghm.de/arbeitsschutz/fachausschuesse/metal-undoberflaechenbehandlung/sachgebiete/schadstoffe-in-der-schweisstechnik.html) which
was specially developed for this purpose. In the future, there will be the possibility to record the process-specific, material-specific and workplace-specific general conditions by means of this sheet.
• For the evaluation of the hazards caused by different
types of welding fumes, an empirical model has been
developed. It is based on measuring results from the
lab and the workplace as well as on occupational
medical findings and experience with regard to the
effects of hazardous substances. The exposure of the
welder to welding fumes at the workplace depends
on a series of different factors. They include the process/material combinations used which are responsible for the amount of the relevant gaseous and particulate substances, the emissions (see below under
I) and the workplace conditions, e.g. ventilation situation, spatial conditions and head/body position
of the welder (see below under II).
The effect of the different welding fume types on persons
has been considered in a differentiated way, namely with
respect to exposure of the respiratory tract, exposure of
the lung and carcinogenic hazard. Additional hazardous
effects on other organs in the human body were not included in the model. The model may be used for the calculation of welding fume hazard years (Schweißrauchgefährdungs-Jahre, SchwRGJ) on the basis of a calculated
hazard figure (Gefährdungszahl GZ) on the one hand and
identified welding years on the other hand as follows:
SchwRGJ = GZ x welding years
GZ = [Ep x Wp + EGx WG] x (1/10) x L x R x Kp
The first term of this equation contains the process-specific and effect-specific factors (E factors and W factors)
and the second the workplace-specific factors (L, R and
Kp factors):
I) Ep
EG
Wp
WG
emission rates – factor for particulate
substances
emission rates – factor for gaseous substances
effect factor for particulate substances
effect factor for gaseous substances
II) L ventilation situation – factor
R spatial conditions – factor
Kp head/body position – factor
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The welding years are calculated from the estimation of
the arcing time or the duty cycle (ED) of the torch and the
working hours of the welder as follows (the total welding
time (years, months or weeks) is considered)):
III) Exposure time (shift-related; per shift x 220 per year
[hours/year (h/a)]; for 1 shift and ED ≈ 40 to 50 %)
1 shift (8 h/shift) ED 4h exposure time 880 h/a
¾ shift (6 h/shift) ED 3h exposure time 660 h/a
½ shift (4 h/shift) ED 2h exposure time 440 h/a
¼ shift (2 h/shift) ED 1h exposure time 220 h/a
With regard to the process-specific and effect-specific factors (I)
For the first step, the emission factors during welding
(EP and EG) were established. The welding processes were
divided into four groups according to emission rates and
correlation factors between the processes (process-specific hazard figure (GZ)E) were specified, Table 1. The hazard figures related to emission groups and emission rates
were presented as follows:
nE : mE : hE : shE = 1 : 3 : 9 : 5
The process-related hazard figure (GZ)E for the relevant
emission category thus results as follows:
nE:
mE:
hE:
shE:
factor 1 =
1
factor 1 x 3 =
3
factor 1 x 3 x 9 = 27 =
27
factor 1 x 3 x 9 x 5 = 135 = 135
The effect factors (WP and WG) were much more difficult
to specify than the technical factors. A differentiated consideration of the specific effect intensity of the relevant
key components in welding fume was carried out in a first
step. Experience gained within the framework of workplace-related provocation tests, anamnesis findings and
course observations were used for key components which
could not be classified in this way according to literature
data.
A simplified procedure is suggested for practice: Limit
values and ranges of limit values are used and, similar to
the emission rates, effect-specific hazard figures are defined. Here, a distinction is made between the three effects
lung-stressing, toxic and carcinogenic , Table 2.
As the hazard depends on the process-specific and
effect-specific factors, the process-specific hazard figures
are then multiplied by the effect-specific hazard figures
and shown in Table 3. The figures in Table 3 (the result of
the multiplication: E x W) refer to a percentage of 100%
toxic or carcinogenic substances in the welding fume.
Since the composition of the welding fumes is very complex and the hazard assessment is carried out on the basis
of specified key components (occupational medically and
toxicologically and also as quantity of the relevant substances in the welding fume) (see as well [9…11]), the
relevant figures from Table 3 are corrected, i.e. multiplied,
by the percentage of the relevant key component in the
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welding fume (for carcinogenic substances with the sum
of the percentages of these substances in the welding
fume) in the following calculation (see examples).
With regard to the workplace-specific factors (II)
Here, the three workplace-specific factors according
to BGI 616 were taken into account:
• ventilation (L),
• spatial conditions (R),
• working position, body posture and head position
(Kp).
They were defined by factors as explained in the following.
In relation to the workplace conditions, the parameter
„ventilation“ was subdivided into the categories “with capture” (with technical ventilation measures) and “without
capture” (without technical ventilation measures) and the
factor L was elaborated accordingly, Table 4. For spatial
conditions, the factor R distinguishes between a non-confined space/room (with V > 100 m³) and a confined space
(with V < 100 m³).
In relation to working position, body posture and head
position, a distinction was made between „head within
the plume“ and „head outside the plume“ and the factor
KP was elaborated accordingly, Table 5. The factors for
spatial conditions (R), for ventilation (L) and for working
position, body posture and head position (KP) are combined in Table 6 and the workplace-specific factors are
multiplied (see formula).
The application of this model was tested on the premises of the Norddeutsche Metall-Berufsgenossenschaft in
cooperation with the then occupational physician of the
BG, Dr. Englitz, in order to evaluate the relevance of the
welding fumes to diseases. Especially for the effect factors,
it was found that the presently available data material
does not suffice to clearly describe the viability and limits
of this model. Therefore, it is suggested to critically check
the organ-related effect factors by a competent working
group in order to have them scientifically substantiated.
Table 5 • Factors for working position, body posture and head position (for particulate
substances).
Table 6 • Correlation between workplace-specific factors.
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SPECIALIST ARTICLES
(0.1% + 0.1%) = 4 and L x R x KP = 1 x 1 x 1 = 1. The hazard figure is:
GZ = 4 x 1/10 x 1 x 1 = 0.4.
b) Welding is done in a confined space without extraction (capture) and the head of the welder is above the
plume, E x W = 2,000 x [(% Cr(VI) compound + % Ni
in the welding fume)] = 2,000 x (0.1 % + 0.1 %) = 4
and L x R x KP = 4 x 4 x 4 = 64. This results in the
hazard figure:
GZ = 4 x 1/10 x 64 = 25.6.
The hazard figure for the TIG welder is between 0.1 and
25.6, as a function of the boundary conditions. Figure 2
shows an overview of the hazard figures (GZ) for different
welding processes.
5 Conclusions
Fig. 2 • Hazard
figures (GZ) for
different welding
processes.
In addition, the model may be used in prevention work
for the assessment of the future risk of a disease or for the
selection of the preventive measures.
4 Examples
TIG welding with unalloyed and low-alloyed filler
metal
The welding fumes are lung-stressing, E x W = 1.
a) Welding is done in a normal space (no confined space) with extraction (capture) and the head of the welder is outside the plume; L x R x KP = 1. From the tables above and the formula, the hazard figure for this
activity results as follows:
GZ = 1 x 1/10 x 1 x 1 = 0.1.
b) Welding is done in a confined space with extraction
(capture) and the head of the welder is above the plume, E x W = 1 and L x R x KP = 16. The hazard figure is:
GZ = 1 x 1/10 x 16 = 1.6.
c) Welding is done in a confined space without extraction (capture) and the head of the welder is above the
plume, E x W = 1 and L x R x KP = 4 x 4 x 4 = 64. This
results in the hazard figure:
GZ = 1 x 1/10 x 64 = 6.4.
TIG welding with high-alloyed filler metal
The welding fumes contain carcinogenic substances.
a) Welding is done in a normal space (no confined space) with extraction (capture) and the head of the welder is outside the plume; E x W = 2,000 x [(% Cr(VI)
compound + % Ni in the welding fume)] = 2,000 x
64
The presented model which focuses on the hazard
figure for the exposure assessment and the examples given
are intended to show that
• Practically no hazard due to welding fumes (= particulate substances) arises from low-emission processes like TIG welding (GZ = 0.1 to 0.4). Even during
working on high-alloyed steels (Cr/Ni steels), no hazard is to be expected – with the exception of welding
work in “confined spaces“ with an unfavourable position of the head above the plume.
• even high-emission processes like manual metal arc
welding with low-alloyed filler metals may lead to
very low hazard figures (e.g. GZ = 2.7), i.e. to a low
hazard, provided that the following optimised general
technical conditions are given:
- efficient extraction is used,
- the welding work in not done in a
“confined space“
and
- the head of the welder is outside the plume.
• the hazard figure (GZ) under the optimised general
technical conditions described above – compared to
contrary conditions (unfavourable conditions like
“confined space“, “no extraction“ and “head of the
welder above the plume“) - may be lower by a factor
of nearly 100.
• the level of the emission rate and the percentage of toxic and especially of carcinogenic substances in the
welding fume is important for the size of the hazard figure (quasi-linear). Therefore, it is the more important
to provide for an influence of at least the three workplace-specific factors: L x R x KP which is as low as possible, best = 1. This is especially important for processes
with high fusion capacities, e.g. during surfacing/hardfacing where high welding fume emission rates at the
same time contain high percentages (e.g. 23 %) of carcinogenic substances and thus result in a high hazard
figure (hazard). This can only be reached by the optimised general technical conditions mentioned.
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•
low-emission/low-hazard processes when carried
out in “confined spaces“ also have a hazard figure
which cannot be neglected (see TIG welding with
high-alloyed filler metal, GZ = 25.6). TIG welding
without filler metal is excluded from this.
Literature
[1] TRGS 528 „Technische Regeln für Gefahrstoff; Schweißtechnische Arbeiten“ (Ausgabe Februar 2009).
[2] N. N.: Virtuelles Museum der Schweißtechnik. DVS, Düsseldorf, http://www.dvs-aft.de/M/.
[3] Flemming, D., u. H. Sossenheimer: Schweißen heute und
Morgen – 1897 bis 1972. Festschrift „75 Jahre Schweißtechnische Gemeinschaftsarbeit – 25 Jahre Deutscher Verband
für Schweißtechnik e. V.“. DVS Media, Düsseldorf 1972.
[4] Kleinöder, N.: Die Geschichte des Arbeitsschutzes in der
Bundesrepublik am Beispiel des Werkes Huckingen nach
1945. Magisterarbeit, Universität, Düsseldorf, Februar 2009,
Fassung 10/2010).
[5] ArbSchG „Gesetz über die Durchführung von Maßnahmen
des Arbeitsschutzes zur Verbesserung der Sicherheit und
des Gesundheitsschutzes der Beschäftigten bei der Arbeit“
Arbeitsschutzgesetz vom 7. August 1996 (BGBl. I S. 1246),
das zuletzt durch Artikel 15 Absatz 89 des Gesetzes vom 5.
DVS Media GmbH,
--
Februar 2009 (BGBl. I S. 160) geändert worden ist“. Stand:
Zuletzt geändert durch Art. 15 Abs. 89 G v. 5.2.2009 I 160.
Hrsg.: Bundesministeriums der Justiz.
[6] Spiegel-Ciobanu, V. E.: Arbeitsschutzregelungen beim
Schweißen, Schwerpunkt Schadstoffe. Tagungsbd. Fachausschuss-Symposium „Schadstoffe beim Schweißen und
bei verwandten Verfahren“ (Mai 2011, Hannover). http://
www.bghm.de/fileadmin/downloads/FA_MO/Schadstoffe/Tagungsband_2011Internetseite_Exemplar_Kurzfassung_kopie.pdf?PHPSESSID=7287a3ba3b23cf22e20f32fe06
e14915.
[7] BGI 553 „Lichtbogenschweißer“ (Ausgabe 2008). Hrg.:
VMBG. Carl-Heymanns-Verlag, Köln 2008.
[8] BGI 554 „Gasschweißer“ (Ausgabe 2009). Hrsg.: VMBG. Carl
Heymanns Verlag, Köln 2009.
[9] Spiegel-Ciobanu, V. E.: Schadstoffe beim Schweißen und
bei verwandten Verfahren. BGI 593, Ausgabe 2008. Hrsg.:
VMBG. Carl-Heymanns-Verlag, Köln 2008.
[10] Spiegel-Ciobanu, V. E.: Beurteilung der Gefährdung durch
Schweißrauche. BGI 616, Ausgabe 2005. Hrsg.: VMBG. CarlHeymanns-Verlag, Köln 2005.
[11] Spiegel-Ciobanu, V. E.: Matrix zur Beurteilung der Schadstoffbelastung durch Schweißrauche. Diss., TH-Aachen
2009. Aachener Berichte Fügetechnik, Bd. 3 2009 (Hrsg.
Prof. Dr.-Ing. Reisgen), ISBN 978-3-8322-8297-4, ShakerVerlag, Aachen 2009.
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