FMC Corporation — Hazardous Materials Safety Interpretation

Page 1Transportatic S. Departme 400 Seventh St., S.W. Washington, D.C. 20590 AUG 25 2000 Mr. Ralph J. Mikida Ref. No. 99-0249 Hazardous Materials Coordinator FMC Corporation 1735 Market Street Philadelphia, PA 19103 Dear Mr. Mikida: I apologize for the delay in responding to your letter concerning the requirement in 49 CFR 173.31(d)(1)(vi) to carefully inspect a frangible (rupture) disc in a pressure relief device prior to each hazardous material shipment. This requirement has its origins in regulations of the Interstate Commerce Commission issued in 1921. The wording of this requirement was most recently revised in a final rule published on September 21, 1995, under RSPA's Docket Nos. HM-175A and 201 (60 Fed. Reg. 49098). As the language of § 173.31(d)(1)(vi) states, the purpose of this type of inspection is to check "for corrosion or damage that may alter the intended operation of the device." For that reason, in response to a comment submitted in a separate rulemaking proceeding under Docket No. HM-216 (61 Fed. Reg. 28666, 28671; June 5, 1996), we stated in the preamble that RSPA and FRA believe in order to fully inspect a rupture disc (both top and bottom), the disc must be removed from the safety vent device. It has been FRA's experience that a rupture disc may appear normal on the top side, but be severely damaged or corroded on the bottom side. You and others have raised concerns about the language of the present rule and its application to persons that forward a loaded tank car received from another location or return a tank car with residue. We anticipate initiating a rulemaking in the near future to address these concerns. Sincerely, I. All. | Edward T. Mazzull oms, em Director, Office of Hazardous Materials Standards 173,31 990249 -#

Page 2FMC Corporation Mack 1735 Market Street 215 299 6000 Philadelphia Pennsylvania 19103 8173.31 99-8249 FMC September 2, 1999 Mr. Edward Mazzullo Director, Office of Hazardous Materials Standards Research and Special Programs Administration U.S. Department of Transportation DHM-10 400 Seventh Street, SW Washington, D.C. 20590 Re: Interpretation of 49 CFR, § 173.31 (d) (1) (vi) Dear Mr. Mazzullo: Transportation We are writing to outline concerns with a Department of referenced above. (DOT) interpretation of the regulations performing an "EXTERNAL visual inspection" to determine that Section 173.31 (d) (1) has to do with a tank car transportation. This includes, as stated in § safe for 173.31 (d) (1) (vi), "The pressure relief device, including a careful inspection of the frangible disc in non-closing alter the intended operation of the device". pressure relief devices, for corrosion or damage that may We understand that the DOT is interpreting $ 173.31(d) (1) (vi) disc each time to require removal and inspection of both sides of a rupture product or residue. This position seems to come from the a tank car is offered for transportation with preamble of HM-216, a final rule unrelated to and which made no changes to this section. In HM-175A and 201, which established the wording in this section, the preamble made no mention of the external inspection requiring removal of the rupture disc and inspecting both the top and bottom. disassemble pressure relief valves. discuss the practical impossibility of having to remove and Therefore, DOT is offering a contradictory interpretation of a section revised confuses the regulated community, but also significantly in a different docket. This not only revises the scope of a regulation without allowing for interpretation in a new rule making. public comment. At a minimum, DOT should include the new#

Page 3safety related consequences do In addition, we feel the time, cost, and possible adverse removing the rupture disc to inspect the bottom side prior not justify the benefits of to each loaded and residue shipment. evidenced in the case of residue cars where they normally This is especiall] accidental release is virtually non-existent. 99% outage and the chance of a 1 rupture disa non- - Many products have no corrosive effect upon the disc specific service and these discs only can fail by is selected by the shipper for their disassembly/reassembly increases the likelihood of overpressure or mechanical damage. Continual well as increase wear, and possible improper damage to the disc and/or its assembly hardware, as reassembly due to human error. - Removing the rupture disc can increase the potential of contaminating the railcar. react adversely to contamination may require Some materials that additional cleaning prior to each reloading. Hydrogen peroxide, which FMC ships in railcars, could grades of this material where even small amounts of be an example of this. We also ship high purity contamination can lead to off spec product. Additional tank car cleaning could add to employee exposure time, environmental discharges, out-of- service time for the railcar, and costs. We recommend that the shipper be required to determine the appropriate frequency for inspecting the product side of the product, the type and material of construction of the disc, disc, but not to exceed 5 years. This would be based on the history. the disc manufacturers recommendations, and the service internal and service equipment inspection requirements for This would be consistent with 49 CFR § 180.509 cars in corrosive service. We respectfully request that you review the actions and consequences that can result from continual disassembly/reassembly of a railcar rupture disc. Sincerely, Ralph 8 Dihila Ralph J. Mikida Hazardous Materials Coordinator#