Welding Safety Precautions
The Occupational Safety and Health Administration (OSHA) provides basic fire prevention and protection precautions to follow in the welding, cutting and brazing standard found in 29 Code of Federal Regulations (CFR) 1910.252(a). Highlights include:
- A responsible individual must inspect the area and identify precautions to be taken preferably on a written Hot Works permit
- Fire extinguishers must be ready for immediate use
- A fire watch lasting at least 30 minutes after the welding or cutting operations is required if more than a minor fire might develop
- All combustibles must be moved 35 feet away or properly protected or shielded
Prohibited areas for welding include
Areas unauthorized by management
Areas where sprinklers are impaired
Areas in explosive atmospheres
Areas near storage of large quantities of readily ignitable materials
Types of Welding
Gas welding: Two metals are joined by melting or fusing their adjoining surfaces. This is done by directing a gas flame over the metals until a molten puddle is formed. The energy for gas welding comes from the combustion of a fuel with oxygen or air. A few of the most popular fuels are acetylene, MAPP gas and hydrogen. Since gas welding is slower and easier to control than electric arc welding, it is often used in applications such as general maintenance work, brazing and soldering.
Arc welding: Two metals are joined by generating an electric arc between a covered metal electrode and the base metals. Heat is produced by the arc, which in turn, melts the metal and mixes the molten deposits of the coated electrode. The arc energy is provided by a power supply unit that furnishes direct or alternating current. The electrodes carry the current to form the arc, producing a gas that shields the arc from the atmosphere, and add metal to control the weld shape. When an arc is struck using a coated electrode, the intense heat melts the top of the electrode. The drops of metal from the electrode enter the arc stream and are deposited on the base metal. The equipment needed for electric arc welding is a power supply, electrode holder, ground clamp, protective shield and welder’s protective clothing.
Oxygen and arc cutting: Metal cutting in welding is the severing or removal of metal by a flame or arc. The most common cutting processes are:
Oxygen cutting: Metal is heated by gas flame, and an oxygen jet does the cutting
Arc cutting: Intense heat of electric arc melts away the metal
Personal Protective Equipment (PPE)
Eye and face protection: 29 CFR 1910.252(b)(2) states the requirements for eye protection. . Helmet, handshield, goggles and safety glasses or combination of these are acceptable protection in various applications. All filter lenses and plates must meet the test for transmission of radiant energy prescribed in ANSI/ISEA Z87.1-2015, American National Standard for Occupational and Educational Personal Eye and Face Protection Devices. According to OSHA 29 CFR 1910.252 (b)(2)(ii)(B), “Helmets and hand shields shall be arranged to protect the face, neck and ears from direct radiant heat from the arc.” Welding helmets with filter plates are intended to help protect users from arc rays and from weld sparks and spatters that strike directly against the helmet. They are not intended to protect against slag chips, grinding fragments, wire wheel bristles and similar hazards that can ricochet under the helmet. Spectacles, goggles or other appropriate eye protection must also be worn to protect against these impact hazards.
When arc cutting and arc welding with an open arc, OSHA requires operators to use helmets or hand shields with filter lenses and cover plates. Nearby personnel viewing the arc must also be protected. Safety glasses with a Shade 2 lens are recommended for general-purpose protection for viewers. Protective clothing: 29 CFR 1910.252(b)(3) refers to the PPE Hazard Assessment in 29 CFR 1910.132. This requires the employer to identify the hazard and appropriate PPE needed to protect the employer from the hazards.
Consensus standard ANSI Z49.1-2012, Safety in Welding, Cutting, and Allied Processes, provides guidance in the safe setup and use of welding and cutting equipment, and the safe performance of welding and cutting operations. Paragraph 4.3 provides more direction on clothing selection for welding tasks. “Clothing shall be selected to minimize the potential for ignition, burning, trapping hot sparks, or electric shock.” It also offers more specific selection guidelines for clothing, gloves, leggings, capes, sleeves, ear plugs, and caps.
Chapter 5 of ANSI Z49.1-2012 provides guidance on ventilation for welding. Ventilation refers to changes of room air as often as necessary to prevent welders and other workers from breathing high levels of airborne contaminants.. Adequate ventilation depends on the following factors:
- Volume and configuration of the space where the welding operations occur
- Number and type of operations that are generating contaminants
- Concentrations of specific toxic or flammable contaminants being generated
- Natural air flow rate where operations are taking place
- Location of the welders’ and other workers’ breathing zones in relation to contaminants or sources
Paragraph 5.4 identifies two types of ventilation: natural or mechanical. Natural ventilation is considered sufficient when necessary precautions are taken to keep the welder’s breathing zone away from the air contaminants and when sampling of the atmosphere shows that concentration of air contaminants are below allowable limits.
If operations do not fall within the natural ventilation guidelines, mechanical ventilation is required. Mechanical ventilation options generally fall into three basic categories:
- Local exhaust
- Local forced air
- General area mechanical air movement
This system consists of fixed or moveable exhaust hoods positioned as near as practicable to the work that are able to maintain a capture velocity of 100 feet per minute to keep air contaminants below the allowable limits. The hood and housing may have to be repositioned by the worker to get maximum benefit from this means of ventilation. Hoods generally remove the fumes and contaminated air through ducting and filtration before being exhausted to the outdoors or recirculated into the work area. General mechanical ventilation may be necessary in addition to local forced ventilation to make up for the air that is being lost.
Local Forced Air
This system, typically a fan, is placed so air is moved horizontally across the welder’s face. General Mechanical Ventilation
This system is generally made up of items like roof exhaust fans, wall exhaust fans, and similar large area air movers. This system is not usually a satisfactory way by itself to control contaminants in the breathing zone of a welder; however, it is often helpful when used in addition to local ventilation.
Chapter 5 also addresses concerns about recirculation, low allowable-limit materials, confined spaces, adjacent persons, brazing furnaces and contaminants containing:
- Fluorine compounds
- Zinc and copper
- Cleaning compounds
- Chlorinated hydrocarbons
Fumes and gases from welding and cutting cannot be easily classified. The quantity of fumes and gases is relative to a combination of the metal being worked, consumable material being used depending on the type of welding being done, contaminants in the atmosphere, and the area the welding is taking place in. Once these are all known personal air sampling can be done to verify the concentration levels of toxic fumes and gases.
Reference OSHA’s 29 CFR 1910 Subpart Q for guidance when performing the following operations:
- 29 CFR 1910.252 General Requirements for all Welding
- 29 CFR 1910.253 Oxygen-fuel gas Welding and Cutting
- 29 CFR 1910.254 Arc Welding and Cutting
- 29 CFR 1910.255 Resistance Welding