In the world of metalwork, welding is a craft of great importance, a process that joins metals together using high heat to melt the parts together, causing fusion. In this vast industry, stainless steel is a prominent material due to its versatility, durability, and resistance to corrosion. However, the process that shapes and molds this material also gives rise to a concerning by-product: welding fumes.
Welding fumes are a complex mixture of tiny particles and gases that can pose significant health risks to welders and those near the welding process. One material of particular concern when welding stainless steel is hexavalent chromium, a toxic compound with health implications if proper safety measures are not in place.
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Understanding the risks associated with welding fumes, especially from stainless steel, is crucial for welders and employers, health and safety officers, and industry regulators. This blog post aims to comprehensively examine these hazards, focusing on hexavalent chromium and other risks associated with stainless steel welding fumes.
Stainless Steel Welding & Fume
Stainless steel, a robust and versatile alloy, is widely used in numerous industries, from construction and automotive to culinary and medical equipment. Its high durability, corrosion resistance, and excellent performance under extreme conditions make it a material of choice for many applications.
The process of welding stainless steel is not vastly different from other welding forms, but it has its unique aspects. Welding stainless steel typically involves the use of several techniques, such as Gas Metal Arc Welding (GMAW), Tungsten Inert Gas (TIG) welding, or Shielded Metal Arc Welding (SMAW). The chosen method depends on the specific application, the material’s thickness, and the weld’s desired quality.
Stainless steel is primarily composed of iron, chromium, and nickel, with traces of other elements like manganese, silicon, and sometimes molybdenum and vanadium. During the welding process, intense heat is applied to the metal. This high-temperature procedure leads to the vaporization of some metal components, creating a plume of fumes and gases.
These elements have a chance of becoming part of the resulting fume. However, the exact composition of the fume will vary depending on factors such as the welding process, the composition of the welding rod, the presence of any coatings on the steel, and the welding techniques and parameters.
Notably, the chromium in stainless steel can transform into hexavalent chromium, a toxic form of chromium, during welding. Hexavalent chromium is a significant concern due to its carcinogenic properties and the potential to cause other health issues.
Other elements like nickel, manganese, and iron can also pose health risks if inhaled or ingested. Nickel, for instance, can cause allergic reactions and is a known carcinogen, while manganese exposure can affect the nervous system.
Hexavalent Chromium: The Hidden Hazard
Hexavalent chromium, often referred to as Cr(VI), is a particular hazard that lurks in the fumes generated during stainless steel welding. As stainless steel contains a significant amount of chromium, some will inevitably be released in the fume during welding. The high temperatures involved in welding can cause the chromium to oxidize, transforming it into its hexavalent state.
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Hexavalent chromium is categorized as a human carcinogen by the ACGIH, with substantial evidence linking it to lung cancer (source: PubMed). When inhaled, the fine particles can penetrate the lung tissue deeply, leading to short-term and long-term health effects. On top of that, the IARC has classified all welding fumes as carcinogenic.
Short-term exposure can lead to irritation and damage to the eyes, skin, and respiratory system. Symptoms can range from runny nose, sneezing, and coughing to shortness of breath, wheezing, and chest tightness. Eye and skin contact can result in burns and severe skin ulcers.
Long-term exposure, however, poses 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. Additionally, it can potentially cause kidney or liver damage and has been associated with nasal and sinus cancers (source: National Cancer Institute).
Other Hazards in Stainless Steel Welding Fumes
While hexavalent chromium is a primary concern in stainless steel welding fumes, it’s not the only risk to be mindful of.
- Nickel: Another significant constituent in stainless steel, nickel can lead to allergic reactions, including skin rashes often known as “nickel itch.” Chronic exposure can also result in lung and nasal cancers. Additionally, nickel can cause respiratory irritation and harm the kidneys over time.
- Iron: Welders often experience a condition known as “metal fume fever,” commonly caused by inhaling iron fumes. Symptoms are flu-like, including fever, chills, and muscle aches. While these symptoms are typically short-term, repeated exposure can lead to more severe conditions like siderosis, a form of pneumoconiosis caused by iron deposits in the lung.
- Manganese: Exposure to high concentrations of manganese can lead to neurological symptoms, often called “manganism.” Symptoms can mimic Parkinson’s disease, including tremors and slowed movements, and can become permanent with prolonged exposure.
- Silicon: Silicon, typically present in stainless steel as silica or silicates, can cause silicosis, a debilitating lung disease, with long-term exposure. Silicosis causes lung inflammation and scarring and can be disabling or even fatal.
- Other Elements: Depending on the specific composition of the stainless steel and any coatings present, other elements like 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 (Irritation of respiratory system, chest pain, breathing difficulty, kidney damage, and emphysema), or certain gases may also be present in the fumes. Each carries its own potential health risks, and air sampling might be necessary to know the fume’s composition.
While it’s critical to understand the individual risks associated with each component of welding fumes, it’s equally important to recognize that these components often don’t act independently. The combined effect of inhaling a mixture of these elements can lead to unpredictable health outcomes and increased risk. Therefore, a comprehensive approach to safety and prevention is essential.
Regulations and Guidelines Regarding Welding Fumes
Given the potential health risks of welding fumes, the United States and Canada have established regulations and guidelines to limit workers’ exposure to these harmful substances. Here’s an overview of these guidelines and how they apply 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
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
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 abide by these guidelines to ensure worker safety. Non-compliance can lead to penalties, including hefty fines and potential lawsuits. Moreover, neglecting these regulations can lead to serious health consequences for employees, impacting their overall well-being and productivity.
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These regulations and guidelines are critical tools for managing the risks associated with welding fumes. They stress the importance of a layered approach to safety – involving engineering controls, personal protective equipment, medical surveillance, and education – to protect workers from the potential hazards associated with stainless steel welding.
Measures to Mitigate Exposure to Welding Fumes
Mitigating the risks associated with welding stainless steel primarily involves proper fume management and implementing effective safety measures. It’s about creating an environment that prioritizes health and safety without compromising on the efficiency of the work process.
We have developed an 8-step method to address welding fume problems. Here are a few ideas that apply directly to stainless steel fume. It would be best to read this article afterward to understand the whole process.
Step 4: Use consumables and materials that produce less toxic fume
Based on the previous discussion, using stainless steel with the lowest chromium concentration possible is in everyone’s best interest.
Ideally, the other pollutants discussed, such as nickel, iron, manganese, and silicone, should also be considered. Still, as it has been established, hexavalent chromium is the biggest problem with stainless steel welding fume.
It does not apply directly to stainless steel, but on a side note, when welding chrome-plated materials, the plating must be removed at least 1 to 4 inches from either side 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 designed to capture and filter out the harmful fumes produced during welding, ensuring they do not linger in the workspace and are not inhaled by workers.
A fume extraction gun is the most efficient way to extract stainless steel welding fume for MIG welding. For TIG or Stick welding, we recommend using a fume extraction arm.
Conclusion
While essential in numerous industries, welding stainless steel comes with risk due to the fumes it generates. These fumes contain a mixture of potentially hazardous substances, most notably hexavalent chromium, which poses significant health risks to those exposed. Other elements such as nickel, iron, and manganese further complicate the health landscape for welders.
While regulations set by health and safety organizations help control these exposures, employers, health and safety officers, and the welders themselves must ensure these guidelines are followed. This adherence involves the implementation of engineering controls such as fume extraction, proper ventilation, and ongoing education about the risks associated with welding fumes.
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