• How do give due consideration to your colleagues working nearby when you are welding?
• What do you think are the risks?
  

In this toolbox we devote attention to the topic welding.

Welding is a method of joining two metals together. During the welding process, they are fused together. This requires a high temperature at the welding site. Auxiliary welding material is sometimes added as well.

We distinguish two methods of welding: electric and autogenous.

In electric welding, an electric arc is used that heats up the material locally to a very high temperature. In fact, electric welding is nothing more than a controlled short-circuit.

In autogenous welding, the heat comes from a gas flame reinforced by oxygen. The combustible gases are:

• Acetylene;
• Propane.

Non-flammable, but oxygen displacement gases are:

• Mixed gases;
• Argon.
  

Fire and explosion hazard

A fire and explosion hazard can arise due to the unnoticed escape of gases and/or oxygen. The escape can be due to leaking hoses or improperly closed blowtorches or defective shutoff valves. This is why it is necessary to make use of a hose failure protection device. This device automatically shuts down the gas and/or oxygen supply in case of major leaks. An explosion hazard is particularly prevalent during autogenous welding performed on vessels that are closed or nearly closed. As the vessel heats up, the gases present in the vessel can ignite.

Exposure to harmful vapours

Harmful gases and vapours can be generated during autogenous welding (and cutting). These can be hazardous to health. For example, think of welding in confined spaces. The hazard can be created by:

• Combustion products;
• Gases that at a high temperature welding flame can manifest from the surrounding air;
• Substances that are released from the treated material.

The combustion of the acetylene or propane by the blowtorch will not only draw oxygen from the oxygen bottle, but from the surrounding air as well. When combustion is incomplete, this can create highly toxic carbon monoxide. Furthermore, in a poorly ventilated space the oxygen concentration in the air will drop due to the consumption of the oxygen by the welding flame.

In addition, the welding flame’s elevated temperature (approx. 3,000°C) causes nitrogen oxides to be formed by combining the nitrogen and oxygen present in the air. These are known as ‘nitric vapours’. These vapours are already highly toxic at low concentrations and can cause illness (pulmonary oedema).

Harmful noise

The process used, the type of voltage and the welder’s surroundings can result in harmful noise. Harmful noise is defined as noise where the sound pressure level exceeds 80 dB(A).

Harmful radiation

Excessive heat

Welder's flash

When, without protection, you come close to an area where welding is being done, you run the risk of burning your skin through UV radiation. Covering your entire skin, including your face/neck/arms/hands, is a must.

Clinical picture

• In welder’s flash (or arc eye) the eyes are swollen, bloodshot, painful and produce tears;
• It is barely possible to open the eyes due to the severe pain;
• Due to the damaged cornea, the patient’s vision is temporarily blurred;
• Painful eyelids are an indication that the facial skin has also suffered damage;
• These complaints do not present themselves immediately after exposure to UV radiation. They occur several hours later, often only during the night.

Do not take welder's flash lightly and take measures to prevent it.

Fire and explosion hazard

• Combustible substances and goods must be removed or sufficiently shielded;
• A suitable fire extinguisher (extinguishing powder or CO₂) must always be present during welding; have a fire guard on duty, if necessary.

Exposure to harmful vapours

• Always ensure there is sufficient ventilation!
• Depending on the coating of the welding electrode used, measures must be implemented to remove the welding fumes and other harmful gases and vapours. There must be good ventilation and a good exhaust system.
• When proper ventilation or exhaust is not possible, a fresh air welding helmet or a special filter mask must be used.
• The protective layer of the welding surface must first be removed.
• Oil, fat and the like must also be removed.

Harmful noise

• Always use hearing protection. Even if the noise level of the welding process itself is sufficiently low, there still is exposure to the noise generated by removing the slag or grinding the weld seams.

Welder's flash

What you can do:

• Welder’s flash generally heals fast and the complaints usually disappear within a week.
• Apply cold and wet facecloths or compresses to the eyes.
• Always have your family doctor check your eyes. Your family doctor can also examine your eyes to check if there is any serious damage or if there are any splinters in the eye, and determine the severity of the burn.
• The doctor has eyedrops that temporarily anaesthetise the cornea. You can open your eyes almost immediately after applying the eyedrops and the symptoms will appear to have disappeared.
• If you have had welder’s flash more often, there is a chance that scarring tissue may be present, which can reduce your sight.

Preventive measures

• As a bystander, never look directly at the crater of the welding arc or even towards the welding light!! Even ‘quickly taking a look’ can injure your eyes.
• Use the required personal protective equipment during welding, such as a welding mask/welding helmet with radiation-adjusted lenses, overalls, welding gloves and neck/throat protection.
• Also consider shielding the welders (welding curtains).
• If there are any employees/third parties present in the surroundings, shield the onsite welding workplaces with welding partitions.
• Perform welding at the workplace in a protected area/welding cabin.
• You must also protect your skin to the maximum extent possible. If you do not do this, you will burn your skin, just like in the sun.