ExxonMobil Chemical Company — Hazardous Materials Safety Interpretation

Page 1U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Ave., SE Washington. DC 20590 Mr. Ronald J. Stokes ExxonMobil Chemical Company Intermediates, Synthetics Product Stewardship P.O. Box 3 140 Edison, New Jersey 088 18 Ref. No. 08-0 1 78 Dear Mr. Stokes: This responds to your June 25,2008 letter requesting clarification of the classification and training requirements in the Hazardous Materials Regulations (HMR; 49 CFR Parts 17 1 - 180) for rail shipments. Specifically, you ask whether the HMR apply to the transportation of materials that release hydrogen into the vapor space of a tank car. According to your letter, you ship various products by rail tank car. Some of these products meet the HMR definition for combustible liquid; others do not meet the definition for any hazard class. In all cases, however, these products release unincorporated hydrogen into the vapor space of the tank car. The vapor pressure is less than 40 psi; however, the hydrogen has been measured at between 2% and 80% concentration. The published flammable limits (LEL-UEL) of hydrogen are 4% and 75%. You ask how these materials should be classed and transported. Under the HMR, hydrogen is classed as a flammable gas irrespective of the pressure it exerts in its packaging. A material that releases a hazardous amount of hydrogen into the vapor space of its packaging during transportation must be classed and transported to address the hazard posed by the hydrogen unless the material is stabilized or inhibited to preclude such a release. For example, the release of hydrogen during transportation could be inhibited through the use of a nitrogen blanket, provided the vapor pressure of the nitrogen does not exceed 40 psi. If the materials you ship are stabilized or inhibited to preclude the release of hydrogen, they may be transported as unregulated materials or as combustible liquids, as appropriate. Alternatively, a material that does not meet the definition of any of the hazard classes defined in Part 173 of the HMR, but that releases hydrogen into the vapor space of its container or packaging under the conditions described in your letter may be described as "UN 1049, Hydrogen, compressed, 2.1" and transported in accordance with all applicable requirements, including appropriate packaging and hazard communication. A material that meets the definition for a combustible liquid and releases hydrogen into the vapor space of its container#

Page 2or packaging under the conditions described in your letter may be described as "UN 1954, Compressed gas, flammable, n.o.s., 2.1 ( hydrogen, compressed; combustible liquid)" and transported in accordance with all applicable requirements, including appropriate packaging and hazard communication. You also ask whether a person who loads or unloads non-hazardous materials to or from a bulk packaging must be trained in accordance with Subpart H of Part 172. The answer is no. The training requirements in the HMR do not apply to persons who handle unregulated materials. However, persons who load andlor unload hazardous materials as described in this letter must be trained. I hope this answers your inquiry. Sincerely, Susan Gorsky Acting Chief, Standards Development Office of Hazardous Materials Standards#

Page 3ExxonMobil Chemical Company Intermediates, Synthetics Product Stewardship P.O. Box 3140 Edison, New Jersey 08818 732 321 6033 Telephone 732 321 6057 Facsimile Qj72. lo! btl/,cab& a ExonMobil lm~fllflg Chemical bgfl/78 June 25.2008 U.S. Department of Transportation Pipeline and Hazardous Materials Safety Admin (PHH- 10) Office of Hazardous Materials Safety 1200 New Jersey Avenue, SE East Building, 2nd Floor Washington, DC 20590 Attn: Mr. Edward T. Mazzullo, Director Office of Hazardous Materials Standards Dear Mr. Mazzullo: Two matters recently arose for which we seek your consideration. The first matter deals with a few select products we produce and ship primarily by rail tankcar. These products vary from being a combustible liquid; n.0.s. to non-regulated but in all cases these products release unincorporated hydrogen into the vapor space of the tankcar. While the vapor pressure is less than 40 psi, the hydrogen has been measured from 2% to 80% concentration in air. The published flammable limits (LEL - UEL) of hydrogen are 4% to 75%. As you can see, we don't havi'a Division 2.1 issue but we are concerned about the potential flammable and/or explosive issue surrounding shipment of these products. 1. Question. Based on the information stated above are there any hazardous material regulatory issues (classification & packaging) we should be concerned with. 2. Question.'Are we correctly classifying our products by limiting the classifications where appropriate to combustible liquid, n.0.s or non-regulated? The second isiue deals with thiihiljkeit of no;-regulated and portable tanks. materkls in sdecification rail tank cars, cargo tanks 3. Question. Are persons who only load and/or unload non-regulated materials to and fiom bulk specification packagings required to be trained in accordance with Subpart H to Part 172? Although we have the utmost appreciation for your time and obligations, we seek a prompt response so that we may ensure only compliant shipments are placed into commerce. c':,! !,,.'.:.,'<.;, , . , :. . , , . ,'>. ' . . . . . . . . . . . Sh6uldtheie ti6iaij~~uesti'on's: cbn$ernirig this r'iqhkst, I may be &itacted at the above address or contact numbers shown below. . . , :i ; . : ( I > . Tharks for your help in this matter. . , , . . . , , . . . . . Sincerely, ' . ~ . . . . . , . i ( ' . . ' .:,.:',? . . , Te1(732)321-6046' ' .," ' ' ' :. .. . . . . . . . . Fax (732) 321-6057 . * . .. . . : . /, Email: ron.j.stokzs@exxonmobil .com , . A Division of Exxon Mobil Corporation#