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Does Plasma Cutting Produce Hex Chrome?

May 12, 2013

What is Hexavalent Chromium?

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 can also be generated by various industrial processes.

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

Does Plasma Cutting Produce It?

Chromium is used in many products and processes, including stainless steel. Hex Chrome is given off when stainless steel is cast, welded, or plasma cut. These thermal processes cause a small percentage of the Chromium in stainless steel to be converted 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.

5/8 inch thick stainless steel parts cut with water injection plasma - Click for larger viewWhat 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:

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.

Eyes - 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.

Workplace or job-specific monitoring must be done 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.

Protective clothing and respiratory protection must be given to employees who have potential exposure.

 Medical surveillance of employees with potential exposure to Cr(VI) must be conducted.

Areas of potential exposure to Cr(VI) must be indicated with warning signs containing 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.

Engineering control must be used to reduce exposures to safe levels (in compliance with the new PEL).

The specific details of the standard are complex and may require the assistance of an occupational health professional to reach full compliance.

Additional Information

For additional information about Hexavalent Chromium contact your occupational health professional and read the OSHA web page at: http://www.osha.gov/SLTC/hexavalentchromium/

References:

http://www.osha.gov/OshDoc/data_General_Facts/hexavalent_chromium.pdf

http://oehha.ca.gov/water/phg/pdf/HexChromfacts082009.pdf

http://www.cbs.state.or.us/osha/pdf/pubs/fact_sheets/fs20.pdf

http://www.osha.gov/OshDoc/Directive_pdf/CPL_02-02-076.pdf

Posted in Cutting Systems , Tagged with Plasma, Safety, Stainless Steel

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