Guide to Welding Safety

The process of welding metals is a very useful operation in the industry today. Although it can be a reasonably simple task, the fumes and gases generated from it can be dangerous. Check out PE Facts to learn how to properly ventilate to keep workers safe while welding!

Welding is one of the most popular ways of fusing metals in industry today. It is the process of melting two similar pieces of metal together. Once welded, the new joint is as strong if not stronger than the pieces that were used to make it. Welding poses some risks from impact, fumes, penetration, smoke, harmful dust, heat and light radiation. Appropriate personal protective equipment can protect you from these hazards.

Types of Welding -- Gas Welding, Arc Welding, Oxygen and Arc Cutting

Gas Welding – Gas welding involves joining two metals by melting their surfaces together. This is done by holding a gas flame to the two metals until they are melted into a puddle. The energy for gas welding is created from the combustion of a fuel with oxygen. Some of the most common fuels are Mapp gas, acetylene and hydrogen. Gas welding is easier to control than electric arc welding, so it is often used for applications such as soldering, brazing and general maintenance work.

Arc Welding – Arc welding is a much different process. In this process the metals are fused by creating an electric arc between a covered metal electrode and the two base metals. The arc produces heat which melts the metals and mixes in the molten deposits of the electrode. The energy from the electrode to form the arc comes from a power source. The electrode carries the current from the power source to form the arc, produces a gas to protect the arc from the surrounding environment, and adds metal to control the weld shape.

The heat of the arc is so intense that when the electrode touches it, the tip of it melts. These drops of metal from the electrode are transported and deposited on the base metal from the arc. Electric arc welding requires a power supply, electrode holder, protective shield, ground clamp, and protective clothing.

Oxygen and Arc Cutting – Metal cutting is the process of severing or removing metal using a flame or arc. The most popular cutting processes are:

  • Oxygen Cutting: Metal is heated by a gas flame and an oxygen jet is used to cut it.
  • Arc Cutting: The intense heat of an electric arc melts away the metal.

Personal Protective Equipment

Eye and Face Protection – The eye and face protection required is different for each application. Helmet, goggles, hand shield and safety glasses, or a mix of all four are acceptable protective equipment for a variety of tasks. Every filter lens and plate must meet the test requirements for transmission of radiant energy prescribed in the ANSI standard Z87.1, Practice for Occupational and Educational Eye and Face Protection.

OSHA 29 CFR 1910.252 states, "Helmets and hand shields shall protect the face, forehead, neck and ears to a vertical line in back of the ears, from the arc direct radiant energy, and weld splatter."

Filter plates are used on welding helmets to protect against arc rays and weld sparks. However, they are not designed to protect against slag chips, wire wheel bristles, grinding fragments, and other similar hazards which can ricochet under the helmet. Eye protection, such as spectacles or goggles, should also be worn to shield from these impact hazards.

When cutting or welding with open arcs, OSHA requires that helmets or hand shields with filter plates and lenses be worn by operators and any others viewing the arc nearby. Spectacles with at least a shade 2 lens are suggested for the protection of any viewers. When resistance welding or brazing, workers must wear face shields, goggles or spectacles in order to protect their eyes and faces from various hazards, depending on the project.

Filter Shade Selection for Type of Welding

Operation

Electrode
Size (mm)

Arc
Current (A)

Min
Shade

Suggested
Shade

Shielded Metal

< 2.5 mm

< 60

7

*

Arc Welding

2.5 - 4mm
4 - 6.4mm
> 6.4mm

60 - 160
160 - 250
250 - 550

8
10
11

10
12
14

Gas Metal Welding and Flux Cored Arc Welding

< 60
60 - 160
160 - 250
250 - 500

7
10
10
10

*
11
12
14

Gas Tungsten Arc Welding

< 50
50 - 150

8
8

10
12

Air Carbon Arc Cutting

150 - 500
< 500
500 - 1000

10
10
11

14
12
14

Torch Brazing

3 or 4

Torch Soldering

2

Carbon Arc Welding

14

Gas Welding
(plate under 1/8" thick, light)

4 or 5

Gas Welding
(plate 1/8" to 1/2" thick, medium)

5 or 6

Gas Welding
(plate over 1/2" thick, heavy)

6 or 8

Oxygen Cutting
(plate under 1" thick, light)

3 or 4

Oxygen Cutting
(plate 1" to 6" thick, medium)

4 or 5

Oxygen Cutting
(plate over 6" thick, heavy)

5 or 6
 

*As a 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 visible light of the operation.

**This applies to where the actual arc is clearly seen. Experience has shown that lighter filters may be used when the arc is hidden by the work piece.

Note: Workers with prescription lenses are not exempt from wearing proper eye protection.

Protective Clothing – ANSI Z49.1 -Welding and Cutting (4.3) states that acceptable protective equipment and clothing for welding and cutting applications will depend on the size, nature and location of the job. Protective clothing must be made of the appropriate materials and provide adequate coverage to minimize the chance of skin burns caused by sparks, spatter or radiation. In order to protect against ultraviolet and infrared ray flash burn, it is best to cover all or as much of the body as possible.

Dark clothing should be worn to help reduce reflection under the face shield. Wool, thick cotton, leather or other heavy materials are preferred because they do not deteriorate easily. Any highly flammable materials that can melt and cause severe burns are not recommended.

According to the ANSI standard, all welders and cutters are required to wear protective gloves that are heat and flame-resistant, such as leather welder's gloves. Gauntlet cuffs may provide extra arm protection, and insulated linings can help protect against high radiant energy.

Durable, flame-resistant, leather aprons are also acceptable clothing when extra protection from sparks and radiant energy is necessary. Similar materials besides leather can also be used for aprons to protect the front of the body.

Ventilation

Ventilation involves changing the air in a room as necessary to prevent a high level of airborne contaminants from being inhaled by workers. It is a way of supplying sufficient breathing air in all welding, cutting, and brazing operations. Adequate ventilation is dependent on the following factors:

  • Volume and configuration of the area that the welding is taking place
  • Number and type of operations that produce contaminants
  • Natural rate of air flow where operations are taking place
  • Breathing zone locations in relation to the sources of contaminants

Proper ventilation can be achieved either naturally or mechanically.

Natural Ventilation – Natural ventilation is acceptable for welding and brazing applications so long as the area in which the work is being done meets the following requirements:

  • More than 10,000 square feet of space per welder;
  • A ceiling height of at least 16 feet or higher
  • Welding is not done in a confined space
  • Welding space does not contain anything that obstructs cross ventilation such as partitions, balconies or structured barriers

If your specific operation does not fall within these guidelines, mechanical ventilation will be required.

Mechanical Ventilation — Mechanical ventilation can be split into two basic options. One option is using a low vacuum system which takes large amounts of air at low velocities. This involves having hoods located a certain distance from the work area. Workers may need to move the hood and housing to get optimal ventilation. Hoods typically filter the fumes and contaminated air outdoors through an exhaust. They should be placed as close to the work as possible, and should effectively provide air flow at a velocity of 100 linear feet (30m) per minute at the furthest distance from the point of operation. The operations that low vacuum systems work best in are arc air gouging, taking afterburner, and arc cutting.

The other mechanical ventilation option is the high vacuum system. This involves having close-range extractors remove fumes and contaminants as near to the work as possible. The hazardous pollutants are successfully extracted before entering the welder’s breathing zone due to the removal of a small volume of air at a high velocity. These types of systems usually have a fan that pulls the contaminated air into a filtration system with a HEPA (High Efficiency Particulate Absolute) filter, and then re-circulates the uncontaminated air back into the work zone. Some benefits of a high vacuum system are a greater flexibility for job adjustment, more effective fume removal, and enhanced visibility to the welder due to fewer clouds of fumes and vapors being generated.

It is not easy to identify the gases and fumes produced from welding and cutting. The amount of fumes and gases depends on the metal being used, other consumable materials being used, as well as the airborne contaminants present.

In order to identify the concentration levels of toxic fumes and gases, air sampling is necessary. Respiratory protection along with mechanical ventilation is required in the cutting and/or welding of certain metals and compounds. For more information, see OSHA 29 CFR 1910.252 on welding regulations.

Commonly Asked Questions

Q. What is a fume plume?
A. The fume plume is the plainly visible cloud of fume which rises straight from the point of welding or cutting. Welders and cutters should try to avoid directly inhaling these fumes. Ventilation is necessary to direct the plume away from the face. (Fume removal is most effective when the air flow is directed across the face of the welder, rather than from behind.)

Q. How can I identify hazardous materials I may be using?
A. Check the Material Safety Data Sheet (MSDS). Welding material suppliers must provide an MSDS or equivalent documentation which classifies the hazardous materials, if any, used in their welding and cutting products.

Q. Where should oxygen not be used and why?
A. Oxygen should not be used as an alternate for compressed air. It should not be used in pneumatic tools, to start internal combustion engines, in oil preheating burners, to dust clothing or work, to blow out pipelines, or to create pressure for ventilation or similar applications. Oxygen should not be used for these applications due to the risk of a raging oxygen-fed fire occurring. Oxygen is not flammable, but it strongly supports combustion. Oxygen can be absorbed by clothing. Even a slight spark can cause severe burns.

Q. What is Mapp gas?
A. Mapp gas is a product that was created as a fuel for welding, cutting, brazing, flame hardening, and metallizing operations. It is very similar to acetylene, but lacks its shock sensitivity and, therefore, can be stored and transported in lighter containers. Mapp gas is caused by the rearranging of the molecular structure of acetylene and propane. It also has a very unique odor so any leakage can easily be detected.

Sources for More Information

ANSI Z49.1, American National Standards Institute-Safety in Welding and Cutting.

29 CFR 1910.251-257, Welding.

Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.