What Is Hex Chrome And Does Plasma Cutting Produce It?

Obviously, when it comes to welding, safety is of the utmost importance. From following best practices to taking extra precautionary measures, it is imperative to follow a “safety first” mentality to protect yourself and those around you. Since hex chrome can pose significant risk to welders, it is necessary to know what hex chrome is and how to reduce exposure to it.

What is Hex Chrome?

Hexavalent Chromium, also known as “Hex Chrome,” or Chromium 6, or Chromium (VI), is a heavy metal that is known to be a potent carcinogen when inhaled. It can occur naturally, but various industrial processes, especially welding, generate these fumes.

Chromium is found in the environment in two principal forms: trivalent chromium (chromium 3) and hexavalent chromium (chromium 6). While Chromium 3 is found naturally in foods at low levels and is an essential human dietary nutrient, Chromium 6 is the toxic form of chromium.

Does Plasma Cutting Produce It?

Many products and processes produce Chromium, including welding stainless steel. Hex Chrome is produced when stainless steel is cast, welded, or plasma cut. These thermal processes cause a small percentage of the Chromium in stainless steel to convert into Hex Chrome.

The chromium in stainless steel is not originally hexavalent, but the high temperature involved in the plasma cutting process results in oxidation that converts the chromium to a hexavalent state.

What are the Health Effects of Hexavalent Chromium

Hexavalent Chromium exposure can occur through direct contact or it can enter the body by breathing air containing the contaminant or by being swallowed. Workplace exposure to Hex Chrome may cause the following health effects:

Links to Cancer

Hexavalent Chromium is classified as a known carcinogen. Workers exposed to Hexavalent Chromium in the workplace have much higher rates of lung cancer.

Respiratory System Effects

Hexavalent Chromium is a respiratory tract irritant to the nose and throat. If an allergy to Hexavalent Chromium develops, inhaling chromate compounds can cause asthma symptoms such as wheezing and shortness of breath.

Eye Irritants

Hexavalent Chromium is an eye irritant. Direct eye contact with chromic acid or chromate dusts can cause permanent eye damage.

Skin Effects

Hexavalent Chromium compounds are not only powerful skin irritants but also can be corrosive. Contact with non-intact skin can also lead to chrome ulcers. If an allergy to Hexavalent Chromium develops, contact with even small amounts can cause a serious skin rash.

What You Need To Know About Plasma and Hex Chrome

On February 28, 2006, the Occupational Safety and Health Agency (OSHA) published a revised standard to protect workers from the potential hazards of Hexavalent Chromium. If you plasma cut stainless steel, you will need to comply with the OSHA standard to protect your employees from Hexavalent Chromium exposure.

What Does this Standard Require Employers To Do?

Occupational exposure to Hexavalent Chromium (Cr(VI)) must be below the Permissible Exposure Limit (PEL) of 5 μg/m3 for an eight hour time weighted average.

Conduct workplace or job-specific monitoring to establish areas of potential exposure and to quantify the potential exposure. Employees who may be exposed to levels of Cr(VI) at or above the new PEL must be informed and corrective measures implemented.

Employers must provide protective clothing and respiratory protection to employees who have potential exposure. Also, employees with potential exposure to Cr(VI) are subject to medical surveillance.

Warning Signs

Warning signs must indicate areas of potential exposure to Cr(VI) and contain the following text.

DANGER; CHROMIUM (VI); CANCER HAZARD; CAN DAMAGE SKIN, EYES, NASAL PASSAGES, AND LUNGS; AUTHORIZED PERSONNEL ONLY; RESPIRATORS MAY BE REQUIRED IN THIS AREA.

How to Further Reduce Exposure to Hex Chrome

Hexavalent chromium is most commonly ingested through inhalation of contaminated dust or fumes in the workplace. Here are some steps you can take to reduce your exposure to hexavalent chromium:

1. Look For Improvements

To reduce exposure to hexavalent chromium, the initial step is to analyze process improvements. Modifications to processes and materials can substantially decrease welders’ exposure to hexavalent chromium. Dealing with weld fumes that are already released into the facility is typically more expensive and troublesome than employing this approach.

Air quality engineers recommend modifying the welding wire as the first change. Changing from flux-core wire to solid wire can dramatically reduce weld fumes and minimize welders’ exposure to hex chrome.

2. Use Engineering Controls

After analyzing process improvements, the next step is to implement engineering controls to safeguard welders from hexavalent chromium. We recommend dust collection systems. For manual welding, source capture systems like backdraft tables or fume guns are highly efficient at capturing weld fumes, including hazardous substances like hex chrome.

In cases where welding operations involve large pieces that cannot fit under a hood or on a table, a fume gun combined with a secondary ambient capture system may be the best solution to capture any remaining fumes. It is advisable to keep robotic applications under hoods whenever feasible.

3. Use a Dust Collection System

The third step involves contemplating the use of an ambient dust collection system. This system can help to minimize fumes throughout the facility and may reduce exposure to a safe level.

However, note that an ambient collector is not sufficient as a standalone air quality solution. Rather, it is most effective when utilized in conjunction with source capture equipment.

4. Implement Additional Safety Measures

In cases where exposure levels remain unacceptably high, consider implementing personal protective equipment (PPE), such as powered air-purifying respirators (PAPRs). When utilized appropriately, PAPR systems can protect welders in nearly all welding scenarios.

Although it is still very important, OSHA regards PPE as a final option, and engineering controls must be employed whenever they are technically feasible.

Additional Information

For additional information about Hexavalent Chromium contact your occupational health professional and read the OSHA web page.