Despite a 2009 directive from the U.S. Department of Defense acquisition chief to phase out the use of hexavalent chromium, the DoD is going forward with a plan to continue use of the cancer-causing corrosion inhibitor.
The DoD in April proposed to amend the Defense Federal Acquisition Regulation Supplement (DFARS) that required minimizing the use of hexavalent chromium in defense weapon systems, subsystems, components, and other items.
Essentially, the DoD is saying that there is no suitable alternative to hexavalent chromium, and that they will continue to allow its use until something better comes along in hopes of staving off what is already a more than $20 billion problem with corrosion.
“Hexavalent chromium compounds are wonderful corrosion inhibitors,” says Paul Yaroschak, Deputy Director of Chemical and Material Risk Management for the Office of the Secretary of Defense, who addressed surface finishers at the NASF Washington Forum recently.
“But we also know that hexavalent chromium compounds are also toxic,” he says. “There are safer substitutes for some applications, and the current DoD policy does provide a strong forcing function to use substitutes where they can meet performance requirements.”
Hexavalent chromium has been deemed a carcinogen that is harmful to humans and the environment. But, there are several different varieties the chromium element, such as ‘chromium 0’ used to make car bumpers shine. The variant ‘chromium 6’ is the one used most extensively for corrosion protection, but it is also the most dangerous as a carcinogen when not applied properly.
Those dangers are what caused DoD Acquisition Chief John Young to issue his memorandum to strengthen the commitment to find alternatives to hexavalent chromium, including asking military branches to help fund the development of substitutes.
“This is an extraordinary situation that requires DoD to go beyond established hazardous materials management processes,” DoD Acquisition Chief John Young wrote, stating that the DoD must take actions to “more aggressively mitigate the unique risks to DoD operations posed by hexavalent chromium.”
But before the DoD can stop using hexavalent chromium for corrosion protection, Young says ion his memo that the ‘Program Executive Officers’ of each military branch to certify to the DoD’s Corrosion Control and Prevention Executive that an acceptable substitute is available and works just as well.
The request to amend the DFARS regulations will allow use of hexavalent chromium if it is specifically authorized “at a level no lower than a general or flag officer or a member of the Senior Executive Service from the Program Executive Office or equivalent level.”
‘The DoD can’t specify hex chrome in contracts unless executive level approval,” Yaroschak says. “Contractors can’t provide deliverables with hex chrome greater than 0.1% by weight, and contractors are liable for providing unapproved hex chrome deliverables.”
“Aerospace and defense are almost the only users of chromium 6,” says Keith Legg of Rowan Technology Group in Libertyville, IL and technical manager for the DoD initiative ‘Advanced Surface Engineering Technologies for a Sustainable Defense’ (ASETSD).
“Because of costs and qual, and the large number of legacy systems, chromium 6 will be around for some time yet,” he says.
Legg said the ASETSD is assisting with DoD research on suitable hexavalent chromium alternatives. Research so far has focused on development of low VOC paint systems, chromate-free finishes, validation of chrome plate alternatives, cadmium plate alternatives, understanding of non-Cr6+ corrosion inhibitors, and faster and better qual tests.
“We do need improved technologies, but the biggest impact would be to qualify and use the clean technologies we already have,” Legg says.
The Environmental Protection Agency and the Occupational Safety and Health Administration also regulates hexavalent chromium emissions and uses under the Clean Air Act and other federal regulations.
OSHA, for example, has mandated a June 1, 2010 deadline for implementing standards that limit a workers’ exposure to chromium 6, requiring that over the course of any 8-hour work shift, the average exposure cannot exceed 5 μg/m3.
What to do about Hard Chromium
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