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6122
Appendix T5 Hot Work
Ventilation/Respiratory Requirements |
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1.0
Purpose
Respiratory hazards are often associated with hot work operations (in particular welding). In order to control exposure to harmful gases/fumes, local or general exhaust ventilation is required during welding operations. This appendix provides Jefferson Lab’s minimal hot work ventilation requirements.
Mechanical ventilation must be provided during hot work operations
when any of the following exists:
· There is less than 10,000 cubic feet of space per operator
·
Ceiling height is less than
16 feet
·
Welding in a confined
space
·
Fluxes or coatings contain
fluorine compound
·
Base metal or other
products involved in the weld including zinc or copper
· Oxygen cutting or brazing using a flux or iron powder
· Gas shielded arc cutting
Contaminated air,
exhausted from a working space, must be discharged into the open air and away
from fresh intake air sources.
NOTE: Welding in
confined spaces requires additional ventilation consideration. See ES&H Manual Chapter
6160 Confined Space Entry for additional requirements. |
The process steps for this procedure are performed in coordination with ES&H Manual Chapter 6122 Hot Work (i.e. Welding, Cutting, Brazing, and Grinding) Safety Program.
3.0
Responsibilities
NOTE: Management authority may be delegated to a task qualified
Jefferson Lab employee at the discretion of the responsible manager.
3.1
Qualified Hot Work Operator
· Request an equipment/area hazard evaluation from Industrial Hygiene if your work or area meets the criteria defined in Section 2.0 (Scope) above. See ES&H Manual Chapter 6630 Respiratory Protection Program.
3.2
Supervisor/Technical
Representative (TR – formerly SOTR)/Sponsor
·
Ensure cleaning and maintenance of ventilation systems are
scheduled in accordance with hazard evaluation requirements.
4.0
Good Work Practices
Step 1:
Identify the
Hazards for the particular hot work operation.
Hazards will depend on:
·
The type of hot work.
·
The materials (base metals, surface coatings, electrodes)
to be used.
·
The environmental conditions (outside or in a confined
space).
Step 2:
Review the Safety Data Sheet (SDS)
·
Identify the materials to be used
·
Determine what fumes may be generated. Some fumes, such
as those released from welding on a cadmium-plated surface, can be fatal in a
relatively short time. See Section 5.0 (References) below.
Step 3:
Implement
Appropriate Control Methods
·
Substitute less hazardous materials if possible (e.g.,
use cadmium-free silver solders and/or asbestos-free electrodes).
Step 4:
Ensure Adequate
Ventilation.
The typical ventilation systems used at Jefferson Lab
include, but are not limited to:
·
Local Exhaust
Ventilation – Removes fumes and gases at the source.
·
Partial Enclosure – Ventilated
workbench or hoods positioned as close to the point of welding as possible.
·
General
Ventilation – Roof vents, open doors and/or windows, roof, and/or floor fans to move
air through the entire work area. These methods are not as effective as local
exhaust ventilation and may actually spread hazardous material around the
workplace. However, general ventilation is helpful when used to supplement
local ventilation.
The below table lists examples of potential
respiratory hazards associated with hot work:
Substance |
Source |
Potential Health Effects |
FUMES |
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Cadmium |
welding or cutting of metal coated with cadmium some brazing pastes
contain cadmium |
acute irritation of the respiratory passages, delayed pulmonary
edema; lung and kidney damage |
Chromium / Hexavalent |
use of chrome-plated, or stainless steels or of hard-facing and
chrome alloy electrodes |
some forms of chromium have been found to be carcinogenic; other
forms are biologically inert |
Cobalt |
welding
or cutting of certain alloys |
shortness of breath, inflammation of the lungs |
Copper |
Welding, cutting, or brazing |
irritation of eyes, and upper
respiratory system; metal fume fever: chills, muscle ache, nausea, fever, dry
throat, cough, lassitude weakness, exhaustion); metallic or sweet taste;
discoloration of skin, hair |
Fluorides |
certain fluxes contain fluoride and can give rise to dust, fume and
vapor |
irritation of eyes, throat, respiratory tract and skin; long-term
exposure can lead to bone hardening |
Iron |
welding or cutting of ferrous materials |
serositis (temporary): inflammation of the lung due to iron
deposition |
Lead |
welding or cutting of metal coated with lead or lead-based paints |
central nervous system & gastro-intestinal effects |
Manganese |
use of manganese-containing electrode cores, coatings or wire;
welding of manganese steel |
metal fume fever, nervous system |
Molybdenum |
welding or cutting of molybdenum-containing alloys |
bronchial irritation, liver and kidney changes |
Nickel |
welding and cutting of nickel-plated and stainless steels |
irritation of respiratory tract; potentially carcinogenic |
Silica (and silicates) |
certain fluxes or dirt contamination could cause silica fume
emissions |
amorphous and not regarded as harmful |
Vanadium |
use of certain filler wires and special alloy steels |
eye and respiratory tract irritation; chemical pneumonia |
Zinc |
welding or cutting of galvanized steel |
metal fume fever |
Other Metals |
welding may produce fumes of other metals such as aluminum, copper,
magnesium, tin, titanium and tungsten |
no known serious health disorders are known to be due exposure to
these fumes |
GASES |
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Oxides of Nitrogen |
formed by the direct
combination of oxygen and nitrogen in the air surrounding the arc or flame |
in confined spaces can build up to levels that can cause respiratory
irritation or delayed pulmonary edema |
Ozone |
formed by certain welding operations, particularly when high
amperages are involved, by the action of ultraviolet radiation on oxygen in
the air |
very irritant to the upper respiratory tract and lungs (effect may be
delayed) |
Carbon Monoxide |
reduction of carbon dioxide shielding gas and to some extent in all
welding operations due to reduction of consumables or incomplete combustion
of acetylene |
can cause drowsiness, headaches and nausea; unconsciousness and death
can result in extreme cases |
Carbon Dioxide |
shielding gas or combustion product |
can be an asphyxiant |
Phosgene |
formed by the oxidation of chlorinated hydrocarbons (trichloroethylene,
etc.) in the atmosphere or on the weld piece |
irritation to the respiratory tract (and lung damage) after a latent
period of several hours |
Phosphine |
formed when welding steel coated with rust proofing compound |
irritating to the eyes, nose and skin; may also cause serious effects
on lungs and other organs |
Lack of Oxygen |
inert gases (argon, helium, etc.) exclude oxygen from confined spaces
(as can carbon dioxide) |
can cause asphyxiation |
Pyrolysis Products |
formed by the thermal decomposition of the resins in primers and
paints - could include phenol, formaldehyde, acrolein, isocyanates and
hydrogen cyanide |
can cause a wide variety of health effects |
6.0
Revision Summary
Revision 1.2 – 09/07/21 – Updated ‘ESH&Q’ to ‘ES&H’; updated contact information; other minor edits. No approval required.
Revision 1.1 – 06/16/16 – Replaced Material Safety Data Sheet (MSDS) with Safety Data Sheet (SDS)
Periodic Review – 03/25/16 – No changes per TPOC
Revision 1.0 – 04/14/11 – Updated to
reflect current laboratory operations
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ISSUING
AUTHORITY |
TECHNICAL
POINT-OF-CONTACT |
APPROVAL
DATE |
REVIEW DATE |
REV. |
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ES&H Division |
06/16/16 |
09/07/24 |
1.2 |
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