Welding Hazards: Key Risks & Safety Tips Explained

I. Hazards of Welding Operations

In safety technology, factors that affect production safety are called hazardous factors.

The diversity of modern welding methods means that welders often come into contact with flammable and explosive gases and materials, electric motors, electrical appliances, machinery, and even work in poor environments such as confined spaces, high altitudes, or underwater. Therefore, the main hazards in the welding process include fire, explosion, electric shock, scalding, acute poisoning, high-altitude falls, and object strikes.

The main hazards of gas welding and cutting are fire and explosion. Electric shock in arc welding is a common major hazard in various welding methods that use electrical energy converted into thermal energy, and there is also a risk of machine damage during resistance welding. There are also unique hazards in various special working environments, such as the risk of falling from heights in high-altitude welding and cutting operations.

II. Harmful factors in welding operations

In safety technology, factors that affect human health are called harmful factors.

During welding operations, harmful factors affecting human health can be divided into two major categories: physical harmful factors and chemical harmful factors. Under welding conditions, harmful factors have a long-term effect on the human body, posing health risks. Physical harmful factors that may exist in the welding environment include arc radiation, high-frequency electric fields, radiation, thermal radiation, metal splashes, and noise, etc., and chemical harmful factors may include welding fumes and harmful gases. The harmful factors of various welding methods are shown in Table 13-1.

Table 13-1 Harmful factors of various welding methods

1. The numbers in the table indicate the degree of impact (for reference); ① minor; ② moderate; ③ strong; ④ strongest.

2. Tungsten inert gas welding, plasma arc welding, and cutting, when using thoriated tungsten electrodes there is slight radioactivity, using ceriated tungsten electrodes there is no radioactivity;

3. When using high-frequency arc initiation, for situations with frequent arc starts, high-frequency electromagnetic fields are harmful.

1. Arc radiation

The temperature of the welding arc is high, the temperature of the arc in shielded metal arc welding reaches above 3000°C, and the temperature at the center of the arc column in plasma arc reaches 18000~24000°C, producing intense arc light, mainly intense visible light and invisible ultraviolet and infrared rays.

The skin surface exposed to ultraviolet radiation from the welding arc turns deep black. The skin exposed to infrared radiation from the welding arc will suffer thermal burns. The impact of arc radiation on visual organs is shown in Table 13-2. Comparison of arc radiation intensity for different welding methods (ultraviolet part) is shown in Table 13-3.

Table 13-2 Effects of Electric Arc Light on Visual Organs

Table 13-3 Comparison of arc radiation intensity for different welding methods (Ultraviolet part)

2. Welding fumes

Various fumes are generated during welding and cutting operations. Fumes are particles of metals, non-metals, and their compounds produced during the melting process of the materials being welded and cut, and the welding materials. Fumes are a general term for smoke and dust, with those having a diameter between less than 0.1μm called dust.

The dust emission amounts of several types of arc welding are shown in Table 13-4.

Table 13-4 Dust emission amounts of several types of arc welding

The chemical composition of structural steel welding rod fumes is shown in Table 13-5.

Table 13-5 Chemical composition of structural steel welding rod fumes (mass fraction) (%)

CO ₂ The measured concentrations of harmful gases and fumes during welding are shown in Table 13-6.

Table 13-6 Measured concentrations of harmful gases and welding fumes during CO2 welding

During the welding process, long-term exposure to fumes can cause welder’s pneumoconiosis, metal fume fever, and manganese poisoning among other diseases. Pneumoconiosis is one of the major issues in welding safety and health with the largest impact.

The onset of pneumoconiosis is generally slow, with symptoms including shortness of breath, coughing, expectoration, chest tightness, and chest pain. Some patients with pneumoconiosis also experience weakness, loss of appetite, reduced lung capacity, and weight loss.

3. Harmful gases

Welding and cutting operations produce various harmful gases, mainly including ozone, nitrogen oxides, carbon monoxide, CO ₂ , and hydrogen fluoride. The maximum allowable concentration values specified in the GBZ1-2010 standard are shown in Table 13-7. Ozone concentrations for various argon arc welding methods are shown in Table 13-8.

Table 13-7 Welding harmful gas measurement values

① Measurement values for poorly ventilated areas such as cabins, boilers, tanks, etc.

② Refer to the values specified in CB11719.1 ~26 ~1989; *Short-term exposure permissible concentration.

Table 13-8 Ozone concentration for various argon arc welding methods

Ozone is produced by the photochemical action of ultraviolet radiation on air. When the concentration of ozone exceeds the permissible level, it often causes dry throat, coughing, chest tightness, fatigue, dizziness, and body aches, and in severe cases, it can cause bronchitis.

Ammonia oxides are formed by the recombination of ammonia and oxygen molecules in the air under the high temperatures of welding. The nitrogen oxides in welding fumes are mainly ammonia dioxide and nitric oxide. Because ammonia oxide is unstable, it easily oxidizes into nitrogen dioxide. Nitrogen oxides are irritant gases that can cause severe coughing, breathing difficulties, and general weakness.

Carbon monoxide produced during welding and cutting operations is a toxic gas that enters the bloodstream through the respiratory tract from the alveoli and combines with hemoglobin to form carboxyhemoglobin, which hinders the blood’s oxygen-carrying capacity, causing tissue hypoxia and leading to carbon monoxide poisoning.

Carbon dioxide is an asphyxiant gas; excessive inhalation can cause irritation to the eyes and respiratory system, and in severe cases, can lead to breathing difficulties, perceptual disturbances, pulmonary edema, etc.

The production of hydrogen fluoride is mainly due to the decomposition of fluorite (CaF ₂ ) contained in the alkaline electrode coating under the action of high-temperature electric arcs. Hydrogen fluoride dissolves easily in water to form hydrofluoric acid, which is highly corrosive. Inhalation of high concentrations of hydrogen fluoride strongly irritates the upper respiratory tract and can also cause ulcers of the eye conjunctiva, nasal mucosa, oral cavity, throat, and bronchial mucosa, and in severe cases, bronchitis and pneumonia can occur.

4. Radioactive substances

Tungsten electrodes containing thorium are used in TIG and plasma arc welding and cutting. The burned thorium tungsten electrodes diffuse into the air at the operation site in the form of aerosols. The hazard level is often assessed by measuring the long-lived α-radioactive aerosol turbidity in the site air and α-radioactive contamination on various object surfaces. See Table 13-9 for the radioactive measurement values of tungsten electrodes.

Table 13-9 Radioactive measurement values of thorium tungsten electrodes

As can be seen from the numerical analysis in Table 13-9, during the welding and cutting process using thoriated tungsten electrodes, the radioactive dose produced during welding and cutting is not sufficient to cause health damage. However, sharpening thoriated tungsten electrodes exceeds health standards, and large storage of tungsten electrodes should also take corresponding protective measures. Otherwise, long-term exposure to radiation or frequent small amounts of radioactive material entering and accumulating in the body can cause diseases of the central nervous system, hematopoietic organs, and digestive system.

5. Noise

In the plasma arc spray gun, noise is generated due to fluctuations in airflow pressure, vibration, and friction, and it is ejected at high speed from the nozzle. The sound pressure level during plasma arc spraying can reach 123dB (A), the commonly used power (30kW) plasma arc cutting is 111.3dB (A), and the high power (150kW) plasma arc cutting reaches 118.3dB (A).

The noise values mentioned above all exceed national standards. As the cutting thickness increases, the required power also increases, thus the noise intensity increases as well. Strong noise is also emitted when using air chisels and carbon arc gouging.

Strong noise or long-term exposure to noise can cause hearing disorders, even deafness. Noise adversely affects the central nervous system and cardiovascular system, and can cause high blood pressure, tachycardia, fatigue, and irritability.

6. High-frequency electromagnetic fields

Non-melting electrode argon arc welding and plasma arc welding, cutting, etc., use high-frequency oscillators to initiate the arc, creating high-frequency electromagnetic fields at the workplace. The measured electric field strengths are quite high, see Table 13-10 and Table 13-11.

Long-term exposure to strong high-frequency electromagnetic fields can cause neurological disorders and neurasthenia.

Table 13-10 Manual tungsten electrode argon arc welding high-frequency electric field strength (unit: V/m)

Table 13-11 Plasma Arc High Frequency Electric Field Intensity

7. Other Harmful Factors

Metal spatter is produced by the metallurgical reactions in the molten pool and the transition of droplets, which can cause burns and burn through clothing. Welders working in the environment with the harmful factors mentioned above for a long time is extremely detrimental to their health, therefore appropriate protective measures should be taken.