By Guest Contributor Mike Schmidt with Bluefield Process Safety
“OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations.” – Statement on every OSHA letter of interpretation
Late in July, without fanfare or announcement, OSHA published a new memorandum on the concentrations of highly hazardous chemicals (HHCs) that count toward the threshold quantities of the Process Safety Management (PSM) standard, replacing the controversial memorandum OSHA issued in 2015.
The 05-Jun-2015 memorandum on PSM and Covered Concentration was controversial because it rescinded the OSHA commercial grade policy and more importantly for many, because it signaled that OSHA would begin considering aqueous solutions of hydrochloric acid as a covered HHC under PSM. In addition to suddenly reversing decades-old OSHA policies, the 2015 memorandum also included several technical errors. The uproar highlighted the purpose for the due process of the rulemaking process: agencies sometime make mistakes or fail to take certain concerns into account, and without public input, can fall into the trap of hearing only the echo chamber of their own offices, no matter how well-intentioned.
The 18-Jul-2016 memorandum still replaces the commercial grade policy that OSHA established in 1992 during the first months after promulgating the PSM standard and replaces it with a 1% test similar to that used by the EPA in its Risk Management Planning (RMP) rule. However, it does it in a way that is much more palatable.
The 1% test
The 1% test states that any Appendix A HHC in a process contributes to the threshold quantity (TQ) if it is in a mixture at concentrations greater than 1%. Only the contained amount of the HHC counts toward the TQ, not the entire quantity of the mixture. The test allows for two important exceptions. First, the quantity in the mixture does not count if the partial vapor pressure of the HHC is less than 10 mm Hg. Second, the 1% test does not apply if the HHC has a mixture concentration associated with its listing.
The Partial Pressure Exception
In the case of the exception for partial vapor pressures less than 10 mm Hg, many listed HHCs will not be covered at concentrations significantly greater than 1% because of the low partial vapor pressures of the HHC. Fortunately, the replacement memorandum corrects the error in the rescinded memorandum that indicated that partial vapor pressure is based on weight percent. Because partial vapor pressure is based on both temperature and mole percent, anyone exploring the partial vapor pressure exception will have to show that the partial vapor pressure of the HHC is less than 10 mm Hg in a specific mixture at a specific temperature.
As the replacement memorandum notes, mixtures of alkylaluminum at any concentration will satisfy the partial pressure exception, which essentially delists alkylaluminum. The replacement memorandum also notes that while HBr is listed as an Appendix A HHC, aqueous mixtures of HBr will not be covered at concentrations less than 63% because of the partial pressure exception.
The Listed Concentration Exception
In the case where the HHC has a mixture concentration associated with its listing, then the concentration must be above the listed concentration before the contained amount of the HHC counts toward the TQ. So 20,000 lbs of 60% aqueous ammonia, which is above the listed concentration for aqueous ammonia of 44%, will contribute 12,000 lb of ammonia toward the TQ. Both the rescinded memorandum and its replacement memorandum state that there are 11 chemicals to which this exception applies, although neither actually lists the chemicals. A review of the letters of interpretation affirmed in the replacement memorandum as “currently good statements of OSHA policy” and other letters of interpretation makes it clear that these are the 11 chemicals that OSHA intends:
- Ammonia solutions (>44% ammonia by weight)
- Diacetyl Peroxide (Concentration >70%)
- Ethyl Methyl Ketone Peroxide (also Methyl Ethyl Ketone Peroxide; concentration >60%)
- Formaldehyde (Formalin) [where “formalin” means “37% by weight or greater]
- Hydrogen Peroxide (52% by weight or greater)
- Methyl Ethyl Ketone Peroxide (concentration >60%)
- Nitric Acid (94.5% by weight or greater)
- Oleum (65% to 80% by weight; also called Fuming Sulfuric Acid) [meaning 65% by weight or greater free sulfur trioxide (SO3) in H2SO4]
- Peracetic Acid (concentration >60% Acetic Acid; also called Peroxyacetic Acid)
- Perchloric Acid (concentration >60% by weight)
- Peroxyacetic Acid (concentration >60% Acetic Acid; also called Peracetic Acid)
Notice that this list includes two pairs of synonyms: Ethyl Methyl Ketone Peroxide and Methyl Ethyl Ketone Peroxide, and Peracetic Acid and Peroxyacetic Acid.
The most contentious aspect of the rescinded memorandum was OSHA’s insistence that mixtures of Appendix A HHCs described as anhydrous would be covered under the 1% test, including aqueous solutions. The replacement memorandum now acknowledges that the term “anhydrous” means “without water”, so that aqueous solutions of Appendix A HHCs described as anhydrous are not covered by the PSM standard. This will be huge relief to facilities that use hydrochloric acid. (Hydrochloric acid will still be on the EPA’s RMP list at concentrations greater than 37%, but 20° Baume hydrochloric acid (31.5% by weight) and 22° Baume hydrochloric acid (35.2% by weight) will not suddenly become covered chemicals or contribute to the threshold quantity calculation for OSHA’s PSM standard.)
This acknowledgement that “anhydrous” means “without water” applies to six chemicals on the Appendix A list:
- Ammonia, Anhydrous
- Dimethylamine, Anhydrous
- Hydrochloric Acid, Anhydrous
- Hydrofluoric Acid, Anhydrous
- Hydrogen Cyanide, Anhydrous
- Methylamine, Anhydrous
(That said, keep in mind that aqueous solutions of >44% ammonia are listed separately.)
Timing for Enforcement
Finally, the replacement memorandum addressed the controversial question of timely notice. The new 1% test is a significant departure from the long-standing commercial grade policy. It places many facilities and processes under the PSM standard that have never been covered and employers at those facilities and processes rightly felt like they needed time to comply.
The replacement memorandum includes a new section on OSHA’s interim enforcement policy. Until the end of March 2017, OSHA will not cite based on this new policy, but may cite under the previous “commercial grade concentration” policy. It is not clear whether a process that is no longer covered because of the new policy could be cited based on the previous policy.
The replacement memorandum goes on to state that beginning next April 1 and going to the end of March 2018, processes newly covered because of the new 1% test will not be cited if the employer is making a good faith effort to get in compliance. However, OSHA also states that this forbearance will not apply in the case of a fatality or catastrophe. So, a steady, good-faith effort to comply with this new policy by March 31, 2018 is only a defense against a citation as long as no one gets hurt in the meantime.
What does this mean for you?
For facilities that were scrambling to bring all of the elements of PSM to bear on processes that use hydrochloric acid or hydrofluoric acid, relax. If the facility was not already covered under RMP because of exceeding 37% HCl concentrations or 50% HF concentrations, it is most likely not covered now. That is not to say that any less care should be taken in protecting the safety of workers, the community, and the environment. Hydrochloric acid and hydrofluoric acid are both hazardous chemicals and deserve a great deal of care. That care is because it is the right thing to do, not because you are compelled to comply with the PSM standard.
As for processes that seem likely to be covered because of the new 1% test, don’t draw any conclusions before determining the partial vapor pressure of the HHC at the operating conditions. If the partial vapor pressure is less than 10 mm Hg, the mixture does not count toward the TQ. Depending on the other components in the mixture and its temperature, the partial vapor pressure may be surprisingly low.
Finally, if the new 1% test means that your process is now covered under the PSM standard, then get on with complying with the standard. There are fourteen elements of PSM, from process safety information and RAGAGEP, to PHAs, mechanical integrity, and management of change. It is one of the most complex of all OSHA regulations, meaning that even if you have been making efforts on all fourteen elements, you are still likely to be out of compliance with the specific requirements of the standard. OSHA has allowed you about 20 months to bring your process into compliance. You’ll need all of it.