How many have noticed that OSHA’s listing of Sulfur Dioxide in 1910.119 Appendix A has a special designation?
So what does the “liquid” designation mean?
It is actually a revision error by OSHA. How do we know this? We can turn to the PSM Preamble, Section 3 – III. Summary and Explanation of the Final Rule and see that OSHA had intentions of removing the “liquid” designation, but somehow missed when the standard was published.
Several participants in the rulemaking (e.g., Ex. 3: 6, 45, 51, 150; Ex. 141) advised OSHA that certain chemicals which appeared in Appendix A, including dimethyl sulfide, isopropyl formate, and methyl disulfide had been deleted from EPA’s EHS list based on a reconsideration of the data and a determination that the data did not support the inclusion of the chemicals on the EHS list. OSHA agrees that it is appropriate to delete these chemicals from its list since a redetermination had been made that data and information available did not support their inclusion on the EPA list. OSHA has therefore removed these chemicals from its Appendix. Other changes to OSHA’s Appendix A list include:
(1) a change in the amount of anhydrous ammonia from 5,000 to 10,000 pounds to better reflect its hazards;
(2) a change in the stated threshold quantity of ammonia solutions from 10,000 to 15,000 pounds to better reflect its dilution by water and its consequent decreased flammability and potential adverse health effects;
(3) a change in the amount of 3-bromopropyne (also listed as propargyl bromide) from 7,500 pounds to 100 pounds to reflect its toxic characteristics rather than its reactive characteristics;
(4) elimination of the erroneous description of formaldehyde, in “concentrations greater than 90%,” since no such concentration exists, and the addition of formalin in the description to assure that no doubt exists that formalin is covered under the formaldehyde entry;
(5) an editorial change to peracetic acid (also called peroxyacetic acid) which inadvertently did not include the description “concentration greater than 60%” which was correctly included in the subsequent entry of peroxyacetic acid;
(6) the elimination of the word “liquid” from the description of sulfur dioxide since it may also be a gas and the health hazards are the same regardless of its state;
(7) and changes based on a reevaluation of available information, in the threshold amounts of allylamine from 1500 pounds to 1000 pounds, peracetic acid (also called peroxyacetic acid (concentration greater than 60%) from 5000 pounds to 1000 pounds, and tetramethyl lead from 7500 pounds to 1000 pounds to better reflect their toxic hazards.
I have spoken with some folks at OSHA and confirmed that their position is that the SO2 gas is as bad, if not worse, than the liquid state SO2; however, it is what it is, and OSHA would allow the 1,000 pounds of liquid to be the threshold for PSM application.