Safety in Welding, Cutting, and Allied Processes

ANSI Z49.1:1999
5.2 Breathing Zone Sampling. Where concentrations of
airborne fume contaminants are to be determined by sampling
of the atmosphere, sampling shall be in accordance
with ANSI/AWS F1.1, Method for Sampling Airborne
Particulates Generated by Welding and Allied Processes.
When a helmet is worn, the samples shall be collected
inside the helmet in the welders breathing zone.
5.3 Avoid the Fume. Welders and cutters shall take precautions
to avoid breathing the fume directly.
5.4 Types of Ventilation. If natural ventilation is not sufficient
to maintain contaminants below the allowable limits
referenced in 5.1, mechanical ventilation or respirators
shall be provided.
In cases where the values for allowable exposure limits
vary among recognized authorities, the lower values should
be used to effect the maximum personnel protection.
Fumes and gases from welding and cutting cannot be
classified simply. The composition and quantity of fumes
and gases are dependent upon the metal being worked,
the process and consumables being used, coatings on the
work such as paint, galvanizing, or plating, contaminants
in the atmosphere such as halogenated hydrocarbon vapors
from cleaning and degreasing activities, as well as the factors
itemized in this section for adequate ventilation.
In welding and cutting, the composition of the fumes is
usually different from the composition of the electrode or
consumables.
Reasonably expected fume products of normal operation
include those originating from consumables, base
metals and coating, and the atmospheric contaminants noted.
Reasonably expected gaseous products include carbon
monoxide, carbon dioxide, fluorides, nitrogen oxides, and
ozone.
The recommended way to determine adequate ventilation
is to sample for the composition and quantity of
fumes and gases to which personnel are exposed (see 5.2).
The Occupational Safety and Health Administration
(OSHA) or others may be the authority having jurisdiction.
Although not an authority having jurisdiction, many of
these levels are adopted from the publications of the American
Conference of Governmental Industrial Hygienists
(ACGIH). Refer to E4.1.3, Protective Screens, and Section
7, Confined Spaces.
E5.3 Avoiding the fume can be done by positioning of the
work, the head, or by ventilation which captures or directs
the fume away from the face. Tests have shown that fume
control is more effective when the air flow is directed
across the face of the welder, rather than from behind. Most
of the fume appears as a clearly visible plume which rises
directly from the spot of welding or cutting.
E5.4 Natural ventilation is acceptable for welding, cutting,
and related processes where the necessary precautions
are taken to keep the welders breathing zone away
from the fumes and where sampling of the atmosphere
shows that concentration of contaminants are below the
allowable limits referenced in 5.1.
Mechanical ventilation includes local exhaust, local
forced air, and general area mechanical air movement.
Local exhaust ventilation is preferred.
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