EPA Issues Stricter Hex Chrome Rules

Graph of CrVI Emissions from EPA National Emissions Inventory 2005

Graph of CrVI Emissions from EPA National Emissions Inventory 2005

National Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks; and Steel Pickling— HCl Process Facilities and Hydrochloric Acid Regeneration Plants

On September 19 EPA  published their final hexavalent chromium rules: Federal Register / Vol. 77, No. 182 / P. 58220 / Wednesday, September 19, 2012.   Click on link to download:

EPA Final Hex Chrome Rule, 9-19-2012

The table below summarizes the rule.

  New Limits Previous Limits
Decorative Chromium Plating:
Existing Sources 0.007 mg/dscm 0.010 mg/dscm
New Sources 0.006 mg/dscm 0.010 mg/dscm
Chromic Acid Anodizing:
Existing Sources 0.007 mg/dscm 0.010 mg/dscm
New Sources 0.006 mg/dscm 0.010 mg/dscm
Hard Chromium Plating:
Existing Sources   (small) 0.015 mg/dscm 0.030 mg/dscm
New Sources (small) 0.006 mg/dscm 0.015 mg/dscm
Existing Sources   (large) 0.011 mg/dscm 0.015 mg/dscm
New Sources (large) 0.006 mg/dscm 0.015 mg/dscm

 

These are the lowest hex chrome emission limits in the world.   Many platers , especially decorative chrome platers, have been meeting the existing limits with PFOS fume suppressants.  However, the new rule  bans the use of fume suppressants containing >1wt% PFOS, because it is a long chain perfluorinated compound that is persistent in the environment (PFOS used to be used in manufacturing Scotchgard and similar fabric stain repellents, but those products were reformulated some years back).  There are now short chain perfluorinated compounds on the market that have been successfully tested for fume suppression in chrome plating baths.  EPA claims that the new limits can be met very inexpensively, merely by increasing the amount of fume suppression surfactant in the plating bath.  However, recent testing shows that merely reducing the surface tension of the bath does not in fact reduce emissions.  This leaves platers with the only option of installing far more expensive scrubbers, which will be difficult or impossible for typical small plating companies to afford, especially in the present economy.

The Graph above shows the vast difference that this rule will make to hex chrome emissions.  Simply reducing power plant emissions of CrVI to 99.5% of their current levels would have the same effect as utterly obliterating the coating industry (and driving out all the industries dependent on it, which is most of them).

For more information see the NAS F website discussion of the new rule at http://www.nasf.org/nasf-news.php.

EPA Set to Issue Stricter Hex Cr rules

On July 17, 2012 EPA sent to Office of Management and Budget (OMB) their new proposed MACT (Maximum Achievable Control Technology) for hexavalent chromium.  This is the final step prior to publication in the Federal Register, probably in August.  The rule is aimed at plating shops and will do two things:

  1. Halve the permissable Cr6+ air emissions from chrome plating shops.  Since plating shops account for 0.35% of all Cr6+ emissions in the US based on the EPA’s National Emissions Inventory, this will reduce Cr6+ in the air by all of 1.7 parts per thousand at most.
  2. At the same time ban the use of PFOS over the next 3 years.  PFOS is a very stable, and therefore bioaccumulative chemical that is used in chrome plating baths to reduce Cr6+ air emissions.

What is the effect for most US businesses and consumers?  Chrome plating is used on the tools that manufacture almost every product we use every day – plates for printing dollar bills, rollers to produce the steel and aluminum to make metal products from forks to fork lifts, molds for plastic products from toothbrushes to televisions, dies for stamping out everything from tiny cell phone connectors to coins and car doors.  (Click here for more details on hard chrome alternatives.)

It is also widely used in aerospace and defense, both industries where safety is paramount.  For that reason the Navy pointed out to EPA that they could not possibly qualify a safe alternative to PFOS in 3 years, and the same is true for the aircraft industry, where the landing gear and all the hundreds of hydraulic actuators that control every passenger aircraft are chrome plated.  Why does it take so long to qualify an alternative as safe?  Ask yourself next time you board a plane if you would much rather they just cut out most of that testing.

Trivalent chrome plating has been in use for years, but it is only useful for thin decorative chrome such as you see on Harley motorbikes (which is mostly Ni, by the way, but that is a different story).  Despite the expenditure of many milions or dollars (and euros) nobody has yet been able to commercialize a way of using trivalent chrome for the much more difficult job of making thick, wear-resistant hard chrome coatings.

There is a qualified alternative, HVOF thermal spray coatings, which have been used on all new landing gear designs for a number of years.  It cannot be used everywhere hard chrome is used, but it handles most of it, while aerospace-qualified electroless Ni can handle most of the rest, and Co-based electroplates are being introduced as well.

And for all of those production tools?  There are some new electroplates based on cobalt and on nickel plating, and for some molds and dies there are ultra-hard PVD coatings such as TiN – a lot more expensive, a lot longer lasting, but not readily available for large tools.

But all those alternatives are more expensive, and there is always a tradeoff – the more it costs to make it here, the more it will be made elsewhere.

For more information see New Updates at the National Association for Surface Finishing at http://www.nasf.org/nasf-news.php.

Latest additions to REACH Annex XIV Authorization List

Dec 20, 2011 – 13 new substances sent to European Commission for inclusion in REACH Annex XIV. Substances in Annex XIV cannot be used in the EU without Authorization – a very complicated, expensive, and limited duration proposition.

Chromium trioxide (chromic acid) is one of the most important of all plating chemicals. It is the fundamental building block for hard chrome plating, and is often used for decorative chrome plating as well. Without hard chrome plating many of the major European industries would find it hard to function, including steel and aluminum production (where it is used on mill rolls), and plastics production (where it is used on molds). In addition chromic acid and sodium dichromate are the most common conversion coatings used for aircraft skins, and since hard chrome plating is still widely used for aircraft actuators and landing gear, these chemicals are essential to the European aerospace industry.

Just to make life more complicated, the listed cobalt salts are essential for most of the trivalent passivation alternatives used for zinc alloys, including for the ZnNi coatings that have taken the place of cadmium in the automotive industry, and the similar LHE ZnNi that is beginning to replace Cd plating in aerospace.

As far as we are aware chromic acid is the only one of these substances for which a Consortium has been set up for Authorization.  Individual companies may be seeking Authorization for some other substances, such as sodium dichromate, but if not these chemicals will become unavailable in Europe in 2015.

As of June 2011 these had not yet been adopted by the Commission.