TITLE:	ES&H Manual
DOCUMENT ID:	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.

Welding in confined spaces requires additional ventilation consideration; refer to 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 at the discretion of the responsible manage.

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. (Also see ES&H Manual Chapter 6630 Respiratory Protection Program.)

3.2 Supervisor/Subcontracting Officer’s Technical Representative (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, and

· The environmental conditions (outside or in a confined space).

Step 2: Review the Material Safety Data Sheet (MSDS)

· 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 4.0 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:

Substance	Source	Potential Health Effects
FUMES
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	serousis (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
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 – 04/14/11 – Updated to reflect current laboratory operations.

ISSUING AUTHORITY	TECHNICAL POINT-OF-CONTACT	APPROVAL DATE	EFFECTIVE DATE	EXPIRATION DATE	REV.
ESH&Q Division	Mike Martin	04/14/11	04/14/11	04/14/16	1

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