Welding has a significant position in the realm of metalwork. It’s a technique that binds metals by applying high heat to melt the parts and cause fusion. Among the diverse materials, stainless steel stands out for its adaptability, strength, and corrosion resistance. However, working with this material also creates an unsettling by-product.
Welding fumes are a complex blend of fine particles and gases that can cause considerable health risks to welders and those near the welding process. Hexavalent chromium, a hazardous compound present when welding stainless steel, becomes a concern if suitable safety procedures aren’t observed.
Recognizing the risks of welding fumes, especially those emanating from stainless steel, is essential for welders, employers, health and safety officers, and industry regulators. This blog post seeks to thoroughly discuss these hazards, with a particular emphasis on hexavalent chromium and other risks linked with stainless steel welding fumes.
Stainless Steel Welding Fume
Stainless steel, a resilient and versatile alloy, is extensively used across various industries, such as construction, automotive, culinary, and medical equipment. It’s chosen for many applications due to its impressive durability, corrosion resistance, and superior performance under harsh conditions.
Welding stainless steel doesn’t differ significantly from other materials but has distinct characteristics. Stainless steel welding typically employs several methods, such as Gas Metal Arc Welding (GMAW), Tungsten Inert Gas (TIG) welding, or Shielded Metal Arc Welding (SMAW). The selection of a specific method depends on the application, the material’s thickness, and the weld’s desired quality.
Some important constituents of stainless steel are iron, chromium, and nickel, with small quantities of other elements like manganese, silicon, and sometimes molybdenum and vanadium. During welding, extreme heat is applied to the metal, vaporizing some metallic components and generating a cloud of fumes and gases.
These elements may become part of the resulting fume. However, the exact fume composition can fluctuate based on factors like the welding process, the welding rod, any coatings present on the steel, and the welding techniques and parameters employed.
The chromium in stainless steel can morph into hexavalent chromium, a toxic chromium variant, during welding. Hexavalent chromium is of significant concern due to its carcinogenic nature and potential to cause other health problems.
Other elements, such as nickel, manganese, and iron, can pose health risks if inhaled or ingested.
Hexavalent Chromium in Welding Fume
Hexavalent chromium, also known as Cr(VI), is a particular hazard hidden in the fumes produced during stainless steel welding. Since stainless steel contains a substantial amount of chromium, some will inevitably be in the fume during welding. The high welding temperatures can lead to chromium’s oxidation, converting it into its hexavalent form.
The ACGIH categorizes hexavalent chromium as a human carcinogen, with substantial evidence associating it with lung cancer (source: PubMed). Inhaled fine particles can penetrate deeply into the lung tissue, leading to short-term and long-term health implications. Additionally, the IARC has classified all welding fumes as carcinogenic.
Short-term exposure can result in irritation and damage to the eyes, skin, and respiratory system. Symptoms can include a runny nose, sneezing, coughing, shortness of breath, wheezing, and chest tightness. Contact with eyes and skin can lead to burns and severe skin ulcers.
Long-term exposure, however, carries a more severe threat. Chronic inhalation of hexavalent chromium fumes can lead to changes in the respiratory system, such as the development of occupational asthma (source: European Respiratory Journal), chronic bronchitis, or lung cancer. It can also cause kidney or liver damage and has been linked with nasal and sinus cancers (source: National Cancer Institute).
Additional Hazards Present in Stainless Steel Welding Fumes
Hexavalent chromium is a significant concern within stainless steel welding fumes, but it’s not the only risk to consider.
- Nickel: This key component in stainless steel can trigger allergic reactions, including skin rashes often called “nickel itch.” Prolonged exposure can also lead to lung and nasal cancers. Furthermore, nickel can result in respiratory irritation and kidney damage over time.
- Iron: Welders frequently encounter a condition dubbed “metal fume fever,” commonly caused by inhaling iron fumes. Symptoms resemble the flu, comprising fever, chills, and muscle aches. While these symptoms are typically short-lived, repeated exposure can lead to more severe conditions such as siderosis, a type of pneumoconiosis resulting from iron deposits in the lung.
- Manganese: Inhaling high concentrations of manganese can result in neurological symptoms, often called “manganism.” Symptoms can resemble Parkinson’s disease, including tremors and slow movements, which can become permanent with extended exposure.
- Silicon: Silicon, usually found in stainless steel as silica or silicates, can cause silicosis, a debilitating lung disease, with long-term exposure. Silicosis results in lung inflammation and scarring and can be disabling or deadly.
- Other Elements: Depending on the exact composition of the stainless steel and any coatings present, other elements such as molybdenum (eye, nose, and throat irritation, and shortness of breath), vanadium (irritation of the eyes, skin, and respiratory tract, bronchitis, retinitis, fluid in the lungs and pneumonia), cadmium (respiratory system irritation, chest pain, breathing difficulty, kidney damage, and emphysema), or certain gases may also be found in the fumes. Each carries potential health risks, and air sampling might be necessary to identify the fume’s composition.
While understanding the individual risks related to each component of welding fumes is vital, it’s equally crucial to acknowledge that these components often don’t act separately. The combined effect of inhaling a mixture of these elements can lead to unpredictable health outcomes and an escalated risk. Thus, a holistic approach to safety and prevention is fundamental.
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Regulations and Guidelines for Welding Fumes
Considering the potential health risks associated with welding fumes, the United States and Canada have set regulations and guidelines to restrict workers’ exposure to these harmful substances. Here’s a snapshot of these guidelines and how they pertain to stainless steel welding.
Abbreviations used in the tables:
- TWA: Time-Weighted Average for 8 hours
- STEL: Short-Term Exposure Limit (maximum for 15 minutes)
- C: Ceiling (must never be exceeded)
- (i): Inhalable particles
- (r): Respirable particles
- ALARA: As Low as Reasonably Achievable
Stainless steel welding fume regulations in the US
| OSHA PEL | TWA | C |
| Welding Fumes | 5mg/m3(r) | None |
| Hexavalent Chromium | 5µg/m3 | None |
| Nickel | 1mg/m3 | None |
| Iron oxide | 10mg/m3 | None |
| Manganese | None | 5mg/m3 |
To know more about the maximum concentrations allowed for other substances, you can read the following article: Welding Fume Regulations and Exposure Limits in the US.
Stainless steel welding fume regulations in Canada
| Welding Fumes | TWA | STEL | C |
| AB | ALARA | ALARA | ALARA |
| BC | 10mg/m3 (i) 3mg/m3 (r) | 30mg/m3 9mg/m3 | 50mg/m3 15mg/m3 |
| MB | 10mg/m3 (i) 3mg/m3 (r) | None | None |
| NB | 10mg/m3 (i) 3mg/m3 (r) | None | None |
| NL | 10mg/m3 (i) 3mg/m3 (r) | 30 mg/m3 9 mg/m3 | 50 mg/m3 15 mg/m3 |
| NT | 5mg/m3 | 10 mg/m3 | None |
| NS | 10mg/m3 (i) 3mg/m3 (r) | None | None |
| NU | 5mg/m3 | 10mg/m3 | None |
| ON | 10mg/m3 (i) 3mg/m3 (r) | 30mg/m3 9mg/m3 | 50mg/m3 15mg/m3 |
| PEI | 10mg/m3 (i) 3mg/m3 (r) | None | None |
| QC | 5mg/m3 | 15mg/m3 | 25mg/m3 |
| SK | 5mg/m3 | 10mg/m3 | None |
| YU | 5mg/m3 | 5mg/m3 | None |
| Hexavalent Chromium | TWA | STEL |
| AB, BC | 0.01mg/m3 | None |
| MB, NB, NL, NS, PEI | 0.2µg/m3(i) | 0.5µg/m3(i) |
| NT, NU, SK | 0.01mg/m3 | 0.03mg/m3 |
| ON, QC | 0.01mg/m3 | None |
| YU | None | None |
To know more about the maximum concentrations allowed for other substances, read the following article: Welding Fume Regulations and Exposure Limits in Canada.
Workplaces must adhere to these guidelines to guarantee the safety of their workers. Failure to comply can result in penalties, including substantial fines and possible legal action. Furthermore, ignoring these regulations can have severe health implications for employees, affecting their overall well-being and efficiency.
These regulations and guidelines are essential for handling the risks associated with welding fumes. They underscore the importance of a multifaceted approach to safety, including engineering controls, personal protective equipment, medical monitoring, and education to shield workers from the potential dangers of stainless steel welding.
Strategies to Reduce Exposure to Welding Fumes
The primary ways to lessen the risks of welding stainless steel involve proper fume management and implementing safety measures. The aim is to foster an environment prioritizing health and safety without compromising the work process’s effectiveness.
We’ve formulated an 8-step method to address welding fume problems. Below are some recommendations directly applicable to stainless steel fume. We suggest reading this article for a comprehensive understanding of the entire process.
Step 4: Use consumables and materials that produce less toxic fume
Given the preceding discussion, using stainless steel with the minimum possible chromium concentration benefits all.
While other pollutants such as nickel, iron, manganese, and silicone should also be considered, it’s established that hexavalent chromium is the most significant concern with stainless steel welding fume.
While not directly related to stainless steel, it’s worth mentioning that when welding chrome-plated materials, the plating should be removed at least 1 to 4 inches from both sides of the intended weld.
Step 5: Use welding fume extractors
The best way to manage fumes is through an efficient extraction system. Welding fume extractors are engineered to capture and filter the harmful fumes produced during welding, ensuring they don’t permeate the workspace and aren’t inhaled by the workers.
A fume extraction gun is the most efficient method for extracting stainless steel fume for MIG welding. For TIG or Stick welding, a fume extraction arm is recommended.
Recirculating hexavalent chromium is forbidden in some places, and the extracted fume must be sent outside, even with a filtration system.
Conclusion
While welding stainless steel is integral to numerous industries, it carries risks due to the fumes it emits. These fumes are a combination of potentially harmful substances, notably hexavalent chromium, which presents significant health risks to those exposed. Other elements such as nickel, iron, and manganese also increase the health risks for welders.
While health and safety organizations’ regulations help manage these exposures, employers, health and safety officers, and welders must uphold these guidelines. This compliance entails implementing engineering controls such as fume extraction, adequate ventilation, and continuous education about the risks associated with welding fumes.
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