ES&H Manual



6122 Appendix T5

Hot Work Ventilation/Respiratory Requirements



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.


2.0             Scope


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.


5.0             References

The below table lists examples of potential respiratory hazards associated with hot work:




Potential Health Effects



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


welding or cutting of certain alloys

shortness of breath, inflammation of the lungs


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


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


welding or cutting of ferrous materials

serositis (temporary): inflammation of the lung due to iron deposition


welding or cutting of metal coated with lead or lead-based paints

central nervous system & gastro-intestinal effects


use of manganese-containing electrode cores, coatings or wire; welding of manganese steel

metal fume fever, nervous system


welding or cutting of molybdenum-containing alloys

bronchial irritation, liver and kidney changes


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


use of certain filler wires and special alloy steels

eye and respiratory tract irritation; chemical pneumonia


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


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


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


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


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












ES&H Division

Jenord Alston





This document is controlled as an on-line file.  It may be printed but the print copy is not a controlled document.  It is the user’s responsibility to ensure that the document is the same revision as the current on line file.  This copy was printed on 9/7/2021.