(1) Mechanical
ventilation requirements. For the purposes of this section, mechanical
ventilation must meet the following requirements:
(a) Mechanical ventilation must consist of
either general mechanical ventilation systems or local exhaust
systems.
(b) General mechanical
ventilation must be of sufficient capacity and so arranged as to produce the
number of air changes necessary to maintain welding fumes and smoke within safe
limits.
(c) Local exhaust
ventilation must consist of freely movable hoods intended to be placed by the
welder or burner as close as practicable to the work. This system must be of
sufficient capacity and so arranged as to remove fumes and smoke at the source
and keep the concentration of them in the breathing zone within safe
limits.
(d) Contaminated air
exhausted from a working space must be discharged into the open air or
otherwise clear of the source of intake air.
(e) All air replacing that withdrawn must be
clean and respirable.
(f) Oxygen
must not be used for ventilation purposes, comfort cooling, blowing dust or
dirt from clothing, or for cleaning the work area.
(2) Welding, cutting and heating in confined
spaces.
(a) Except as provided in (c) of this
subsection and subsection (3)(b) of this section, either general mechanical or
local exhaust ventilation meeting the requirements of subsection (1) of this
section must be provided whenever welding, cutting or heating is performed in a
confined space.
(b) The means of
access must be provided to a
confined space and ventilation ducts to this space
must be arranged in accordance with WAC
296-304-05011(2)(a) and
(b).
(c) When sufficient ventilation cannot be
obtained without blocking the means of access, employees in the
confined space
must be protected by air line respirators in accordance with the requirements
of chapter
296-842 WAC, and an
employee on the outside of such a
confined space
must be assigned to maintain communication with those working within it and to
aid them in an emergency.
(3) Welding, cutting or heating of metals of
toxic significance.
(a) Welding, cutting or
heating in any enclosed spaces aboard the
vessel involving the metals specified
in this subsection must be performed with either general mechanical or local
exhaust ventilation meeting the requirements of subsection (1) of this section.
(i) Zinc-bearing base or filler metals or
metals coated with zinc-bearing materials.
(ii) Lead base metals.
(iii) Cadmium-bearing filler
materials.
(iv) Chromium-bearing
metals or metals coated with chromium-bearing materials.
(b) Welding, cutting, or heating in any
enclosed spaces aboard the
vessel involving the metals specified in this
subsection must be performed with local exhaust ventilation in accordance with
the requirements of subsection (1) of this section or employees must be
protected by air line respirators in accordance with the requirements of
chapter
296-842 WAC.
(i) Metals containing
lead, other than as an impurity, or metals coated with lead-bearing
materials.
(ii) Cadmium-bearing or
cadmium coated base metals.
(iii)
Metals coated with mercury-bearing metals.
(iv) Beryllium-containing base or filler
metals. Because of its high toxicity, work involving beryllium must be done
with both local exhaust ventilation and air line respirators.
(c) Employees performing such
operations in the open air must be protected by filter type respirators in
accordance with the requirements of WAC
296-304-09003, except that
employees performing such operations on beryllium-containing base or filler
metals must be protected by air line respirators in accordance with the
requirements of chapter
296-842 WAC.
(d) Other employees exposed to the same
atmosphere as the welders or burners must be protected in the same manner as
the welder or burner.
(4) Inert-gas metal-arc welding. Since the
inert-gas metal-arc welding process involves the production of ultraviolet
radiation of intensities of five to 30 times that produced during shielded
metal-arc welding, the decomposition of chlorinated solvents by ultraviolet
rays, and the liberation of toxic fumes and gases, employees must not be
permitted to engage in, or be exposed to the process until the following
special precautions have been taken:
(a) The
use of chlorinated solvents must be kept at least 200 feet from the exposed
arc, and surfaces prepared with chlorinated solvents must be thoroughly dry
before welding is permitted on such surfaces.
(b) Helpers and other employees in the area
not protected from the arc by screening as provided in WAC
296-304-04011(5)
must be protected by filter lenses meeting
the requirements of Tables I-1A and B (see below). When two or more welders are
exposed to each other's arc, filter lens goggles of a suitable type meeting the
requirements of WAC
296-304-09001(1) and
(3) must be worn under welding helmets or
hand shields to protect the welder against flashes and radiant energy when
either the helmet is lifted or the
shield is removed.
(c) Welders and other employees who are
exposed to radiation must be suitably protected so that the skin is covered
completely to prevent burns and other damage by ultraviolet rays. Welding
helmets and hand shields must be free of leaks and openings, and free of highly
reflective surfaces.
(d) When
inert-gas metal-arc welding is being performed on stainless steel, the
requirements of subsection (3)(b) of this section must be met to protect
against dangerous concentrations of nitrogen dioxide.
(5) General welding, cutting and heating.
(a) Welding, cutting and heating not
involving conditions or materials described in subsection (2), (3), or (4) of
this section may normally be done without mechanical ventilation or respiratory
protective equipment, but where, because of unusual physical or atmospheric
conditions, an unsafe accumulation of contaminants exists, suitable mechanical
ventilation or respiratory protective equipment must be provided.
(b) Employees performing any type of welding,
cutting or heating must be protected by suitable eye protective equipment in
accordance with the requirements of Tables I-1A and B (see below).
(6) Residues and cargos of
metallic ores of toxic significance must be removed from the area or protected
from the heat before welding, cutting or heating has begun.
TABLE I-1A
FILTER LENSES FOR PROTECTION AGAINST RADIANT ENERGY
|
OPERATIONS
|
ELECTRODE SIZE 1/32 IN
|
ARC CURRENT
|
MINIMUM PROTECTIVE SHADE
|
|
Shielded metal arc
|
Less than 3
|
Less than 60
|
7
|
|
welding
|
3-5
5-8
More than 8
|
60-160
160-250
250-550
|
8
10
11
|
|
Gas metal arc
|
Less than 60
|
7
|
|
welding and flux
|
60-160
|
10
|
|
cored arc welding
|
160-250
|
10
|
|
250-500
|
10
|
|
Gas Tungsten arc
|
Less than 50
|
8
|
|
welding
|
50-150
150-500
|
8
10
|
|
Air carbon
|
(Light)
|
Less than 500
|
10
|
|
Arc cutting
|
(Heavy)
|
500-1000
|
11
|
|
Plasma arc welding
|
Less than 20 20-100
100-400
400-800
|
6
8
10
11
|
|
Plasma arc cutting
|
(Light)**
(Medium)**
(Heavy)**
|
Less than 300
300-400
400-800
|
8
9
10
|
|
Torch brazing
|
-
|
-
|
3
|
|
Torch soldering
|
-
|
-
|
2
|
|
Carbon Arc welding
|
-
|
-
|
14
|
** These values apply where the actual arc is clearly seen.
Lighter filters may be used when the arc is hidden by the workplace.
TABLE I-1B
FILTER LENSES FOR PROTECTION AGAINST RADIANT ENERGY
|
OPERATIONS
|
PLATE
THICKNESS...
INCHES
|
PLATE
THICKNESS...
MM
|
MINIMUM*
PROTECTIVE SHADE
|
|
Gas welding:
|
|
Light
Medium
Heavy
|
Under 1/8
1/8 to 1/2
Over 1/2
|
Under 3.2
3.2 to 12.7
Over2.7
|
4
5
6
|
|
Oxygen cutting:
|
|
Light
Medium
Heavy
|
Under 1
1 to 6
Over 6
|
Under 25
25 to 150
Over 150
|
3
4
5
|
* As rule of thumb, start with a shade that is too dark to see
the weld zone. Then go to a lighter shade which gives sufficient view of the
weld zone without going below the minimum. In oxyfuel gas welding or cutting
where the torch produces a high yellow light, it is desirable to use a filter
lens that absorbs the yellow or sodium line in the viable light of the
(spectrum) operation.
|
Note:
|
A worker may use an auto-darkening helmet that allows
for the selection of final filtration settings inside the appropriate range as
described in the tables above. The auto-darkening helmet must be in good
working order and maintained in accordance with the manufacturers
recommendations and guidance.
|
