# Crashworthiness Protection Requirements for Tank Cars; Detection and Repair of Cracks, Pits, Corrosion, Lining Flaws, Thermal Protection Flaws and Other Defects of Tank Car Tanks

- **operation:** document
- **citation:** 60 FR 49048
- **title:** Crashworthiness Protection Requirements for Tank Cars; Detection and Repair of Cracks, Pits, Corrosion, Lining Flaws, Thermal Protection Flaws and Other Defects of Tank Car Tanks
- **source type:** rulemaking
- **agency:** Research and Special Programs Administration
- **status:** historical
- **official:** true
- **published on:** 1995-09-21
- **effective on:** 1996-07-01
- **summary:** RSPA is amending the Hazardous Materials Regulations (HMR) to: Require facilities that build, repair, and ensure the structural integrity of tank cars, to develop and implement a quality assurance program (QAP); allow the use of non-destructive testing (NDT) techniques, in lieu of currently prescribed periodic hydrostatic pressure tests, for fusion welded tank cars; require thickness measurements of tank cars; allow the continued use of tank cars, with limited reduced shell thicknesses, for certain hazardous materials; increase the frequency for inspection and testing of tank cars for added safety; clarify tank car pretrip inspection requirements; expand the use of thermal protection systems and head protection on tank cars to include certain other high hazard materials; add new requirements for bottom-discontinuity protection; require the use of protective coatings on insulated tank cars; prohibit the use of self-energized manways located below the liquid level of the tank; remove ``grandfather'' provisions allowing certain uses of tank cars; and improve the puncture resistance of tank cars used for certain high hazard materials, including those that are poisonous-by-inhalation (PIH) and those determined by the Environmental Protection Agency (EPA) to pose health and environmental risks. These actions are being taken to enhance the safe transportation of hazardous materials in tank cars. The intended effects of these actions are to improve the crashworthiness of tank cars and to increase the probability of detecting critical tank car defects.
- **machine formats:** - **json:** https://regulus.evalyn.ai/document/federal-register-95-22771.json
- **markdown:** https://regulus.evalyn.ai/document/federal-register-95-22771.md
- **app url:** https://regulus.evalyn.ai/document/federal-register-95-22771
- **source url:** https://www.federalregister.gov/documents/1995/09/21/95-22771/crashworthiness-protection-requirements-for-tank-cars-detection-and-repair-of-cracks-pits-corrosion
**body:**

Federal Register, Volume 60 Issue 183 (Thursday, September 21, 1995) [Federal Register Volume 60, Number 183 (Thursday, September 21, 1995)] [Rules and Regulations] [Pages 49048-49083] From the Federal Register Online via the Government Publishing Office [ www.gpo.gov ] [FR Doc No: 95-22771] [[Page 49047]] _______________________________________________________________________ Part II Department of Transportation _______________________________________________________________________ Research and Special Programs Administration _______________________________________________________________________ 49 CFR Part 171, et al. Crashworthiness Protection Requirements for Tank Cars; Detection and Repair of Cracks, Pits, Corrosion, Lining Flaws, Thermal Protection Flaws and Other Defects of Tank Car Tanks; Final Rule Federal Register / Vol. 60, No. 183 / Thursday, September 21, 1995 / Rules and Regulations [[Page 49048]] DEPARTMENT OF TRANSPORTATION Research and Special Programs Administration 49 CFR Parts 171, 172, 173, 179, and 180 [Docket Nos. HM-175A and HM-201; Amdt Nos. 171-137, 172-144, 173-245, 179-50, and 180-8] RIN 2137-AB89 and 2137-AB40 Crashworthiness Protection Requirements for Tank Cars; Detection and Repair of Cracks, Pits, Corrosion, Lining Flaws, Thermal Protection Flaws and Other Defects of Tank Car Tanks AGENCY: Research and Special Programs Administration (RSPA), DOT. ACTION: Final rule. ----------------------------------------------------------------------- SUMMARY: RSPA is amending the Hazardous Materials Regulations (HMR) to: Require facilities that build, repair, and ensure the structural integrity of tank cars, to develop and implement a quality assurance program (QAP); allow the use of non-destructive testing (NDT) techniques, in lieu of currently prescribed periodic hydrostatic pressure tests, for fusion welded tank cars; require thickness measurements of tank cars; allow the continued use of tank cars, with limited reduced shell thicknesses, for certain hazardous materials; increase the frequency for inspection and testing of tank cars for added safety; clarify tank car pretrip inspection requirements; expand the use of thermal protection systems and head protection on tank cars to include certain other high hazard materials; add new requirements for bottom-discontinuity protection; require the use of protective coatings on insulated tank cars; prohibit the use of self-energized manways located below the liquid level of the tank; remove ``grandfather'' provisions allowing certain uses of tank cars; and improve the puncture resistance of tank cars used for certain high hazard materials, including those that are poisonous-by-inhalation (PIH) and those determined by the Environmental Protection Agency (EPA) to pose health and environmental risks. These actions are being taken to enhance the safe transportation of hazardous materials in tank cars. The intended effects of these actions are to improve the crashworthiness of tank cars and to increase the probability of detecting critical tank car defects. DATES: Effective date. The effective date of these amendments is July 1, 1996. Compliance date. Voluntary compliance with the regulations, as amended herein, is authorized November 1, 1995. Incorporation by reference date. The incorporation by reference of certain publications listed in these amendments is approved by the Director of the Federal Register as of July 1, 1996. FOR FURTHER INFORMATION CONTACT: Ed Pritchard (telephone 202-366-0509) and James H. Rader (telephone 202-366-0510), Hazardous Materials Division; or Thomas A. Phemister (telephone 202-366-0635), Office of Chief Counsel, Federal Railroad Administration, 400 Seventh Street, S.W., Washington, D.C. 20590-0001. SUPPLEMENTARY INFORMATION: I. Introduction This final rule consolidates two related notices of proposed rulemaking published under Docket HM-175A [58 FR 52574, October 8, 1993] and Docket No. HM-201 [58 FR 48485 September 16, 1993], that address the safe performance of tank cars used to transport hazardous materials. RSPA believes that, by consolidating these two rulemakings, changes to sections that are affected by both rules will be more easily understood by readers. This preamble discusses separately, for each rulemaking, the notices of rulemaking and comments received in response to these notices. A consolidated ``Review by Section Summary'' summarizes the changes made under this final rule. The Federal Railroad Administration (FRA) has enforcement authority for tank cars and rail transportation. FRA developed these rulemakings jointly with RSPA. II. Docket HM-175A--Crashworthiness Protection Requirements for Tank Cars A. Background Based on research and on the FRA's continuing review of serious accidents, involving the transportation of hazardous materials in tank cars in the United States and Canada, RSPA issued a number of regulations to improve the survivability of tank cars in accidents. 1 In these rulemakings, RSPA required the installation of a tank-head puncture-resistance system (head protection), a coupler vertical restraint system (shelf couplers), insulation, and a thermal protection system for certain high-risk hazardous material ladings. The difference between a ``thermal protection system'' and ``insulation'' is that a ``thermal protection system'' protects a tank from a pool or torch-fire environment. In contrast, ``insulation'' protects the lading inside the tank from ambient, temperature differentials, much like home insulation. The record shows that these systems, working in combination, have greatly reduced the potential harm to human health and the environment when tank cars are involved in accidents. \1\The discussions in the following rulemakings provide greater detail about each of these safety system requirements: Interlocking Couplers and Restrictions of Capacity of Tank Cars, Docket HM-38, 35 FR 14215 (September 9, 1970); Tank Car Tank Head Protection, Docket HM-109, 41 FR 21475 (May 26, 1976); Shippers; Specifications for Pressure Tank Cars, Docket HM-144, 42 FR 46306 (September 15, 1977); Shippers, Specifications for Tank Cars, Docket HM-174, 49 FR 3473, (January 27, 1984); Specifications for Railroad Tank Cars Used to Transport Hazardous Materials, Docket HM-175, 49 FR 3468 (January 27, 1984); Transportation of Hazardous Materials, Miscellaneous Amendments, Docket HM-166W, 54 FR 38790 (September 20, 1989); and Performance-Oriented Packaging; Changes to Classification, Hazard Communication, Packaging and Handling Requirements Based on UN Standards and Agency Initiative, Docket HM-181, 55 FR 52402 (December 21, 1990). --------------------------------------------------------------------------- On October 8, 1993, RSPA published a notice of proposed rulemaking (NPRM) under Docket HM-175A (58 FR 52574) based, in part, on recommendations issued by the National Transportation Safety Board (NTSB) and comments received in response to an advance notice of proposal rulemaking published on May 15, 1990 [55 FR 20242], and a supplemental advance notice of proposed rulemaking published on August 29, 1990 [55 FR 35327]. The NPRM solicited comments on the costs and safety benefits that would be derived should the HMR be amended in the following areas: (1) Tank-head protection; (2) thermal protection; (3) self-energized manways below the tank liquid level; (4) non-pressure tank cars for PIH materials; (5) grandfather provisions allowing use of certain tank cars conforming to former standards; (6) bottom discontinuity protection on tank cars; (7) protective coatings on insulated tanks; and (8) tank cars of limited and designated specifications, with greater protection in accidents for transporting materials determined by EPA to pose health and environmental risks. On January 6, 1994, FRA and RSPA held a public hearing to solicit information to assist in deciding what actions, if any, should be taken to improve the survivability of tank cars involved in hazardous materials accidents. Twelve persons made presentations at the public hearing. In addition, RSPA received 37 written comments in response to the NPRM from representatives of trade associations and the various industries that own, lease, transport, or use tank [[Page 49049]] cars. All written and oral comments were given full consideration. B. Tank Cars Transporting ``Thermally Reactive Materials'' (Materials That May Violently Decompose or Polymerize When Exposed to Fire) In the NPRM, RSPA proposed to require the use of full-head protection and thermal protection on tank cars used for certain materials termed, ``thermally reactive.'' These materials, listed by name, are thought by many to be capable of a violent decomposition or polymerization reaction when exposed to fire. For these materials, the critical temperature for the tank car, and its thermally reactive lading, may be the heat at which the material undergoes decomposition or polymerization--as opposed to the temperature at which the steel of the tank becomes so plastic, it begins to lose tensile strength. The proposal was based on several accidents involving thermally reactive materials. For example, on August 2, 1988, at 9:00 p.m., in Brazoria, Texas, 13 cars of a Union Pacific freight train derailed. 2 Seven of the derailed tank cars contained acetaldehyde, and none of these tank cars had a thermal protection system, which was not required. Two acetaldehyde tank cars sustained coupler punctures and released their contents, which ignited. The resulting fire engulfed four other acetaldehyde tank cars, and each of them had a total failure or rupture of the tank shell within 5 to 10 minutes after the derailment. Witnesses reported 3-4 explosions between 9:05 p.m. and 9:10 p.m. \2\Union Pacific Derailment at Brazoria, Texas, FRA Accident Investigation No. 137-88, Railroad Report No. 0888H0200, August 2, 1988. --------------------------------------------------------------------------- In another accident, NTSB found that the puncture of a tank car containing hydrogen peroxide resulted in a release of lading and, when the hydrogen peroxide combined with contaminants on the ground, a chemical reaction occurred causing a fire. 3 The fire heated and ignited nearby polyethylene pellets, causing an explosion of the hydrogen peroxide tank car and releasing a force equivalent to an explosion of 10 tons of TNT (trinitrotoluene). \3\Collision and Derailment of Montana Rail Link Freight Train with Locomotive Units and Hazardous Materials Release, Helena, Montana, February 2, 1989, National Transportation Safety Board Report NTSB/RAR-89/05, National Transportation Safety Board, Washington, D.C. --------------------------------------------------------------------------- Most commenters opposed the requirement for full-head protection or thermal protection on tank cars used for thermally reactive materials. In clarifying its comments on the NPRM, the Association of American Railroads (AAR) stated that full-head protection is not necessary for tank cars used for these materials, unless the materials pose another hazard that warrants such protection. Other commenters, such as American Petroleum Institute (API), Chemical Manufacturers Association (CMA), and the Compressed Gas Association, Inc. (CGA), suggested that RSPA open a new ANPRM to address these materials. A commenter stated-- the creation of this category has ramifications that reach far beyond this particular rulemaking, which deals with one mode of transportation (rail) and one type of packaging (tank cars). We are concerned with the likelihood that, in the future, the Department will expand the regulation of TRMs to affect other modes of transportation and types of packaging. Other commenters objected to the proposal to identify by list, rather than by definition, certain existing hazardous materials that would be designated ``thermally reactive.'' CMA challenged the placement of several chemicals on the list, such as ``styrene, monomer inhibited,'' ``vinyl toluene,'' ``vinylidene chloride,'' ``sulfur trioxide,'' and ``hydrogen peroxide.'' CMA further stated that-- [s]tyrene, for example, is flammable and can polymerize in an accident but solidifies causing little or no harm to the environment. For hydrogen peroxide tank cars, the proposed rule would create a safety hazard by requiring thermal protection. Another commenter stated that ``[s]ome of the materials on the list react violently when exposed to heat differentials and may decompose with explosive force * * * Other materials, however, decompose through polymerization into substances of relatively little hazard.'' The commenter further explained that the key to the polymerization of styrene is the absence of the inhibitor. Styrene is typically shipped with inhibitor concentrations great enough to cover fairly lengthy, unexpected delays in transportation. If a tank car of styrene is exposed to extreme external heat, disregarding its flammable nature, the inhibitor will dissipate rapidly as the temperature of the material rises above 125 deg.F., which will allow the polymerization process to begin. As a result of the polymerization, the internal heat of the product will increase, and, with increasing temperature, the process will accelerate. Several commenters opposed the requirement for a thermal protection system on tank cars used to transport ``hydrogen peroxide.'' One of the commenters stated that hydrogen peroxide does not polymerize or burn, and the products of decomposition--water and oxygen--are not toxic. Two commenters, Eka Nobel and FMC Corporation (FMC), furnished independent analyses of the fire effects on tank cars containing ``hydrogen peroxide.'' Eka Nobel contracted with the IIT Research Institute (IITRI), which used FRA's computer model to analyze the fire effects on a tank car containing hydrogen peroxide. 4 The results of IITRI's analysis indicate that a tank car constructed from stainless steel will meet the thermal protection criterion for withstanding the effects of a pool fire. \4\``Temperatures, Pressures and Liquid Levels of Tank Cars Engulfed in Fires,'' NTIS DOT/FRA/OR&D-84/08.11, (1984), Federal Railroad Administration, Washington, DC. --------------------------------------------------------------------------- FMC furnished a detailed, mathematical heat transfer model using a correlation contained in a National Fire Protection Association (NFPA) publication, ``NFPA Pamphlet No. 30.'' FMC stated that for materials that decompose exothermically, such as hydrogen peroxide, thermal stability requires that the heat losses to the surroundings balance the heat generated by the decomposition. Failure to remove the heat of reaction could lead to runaway decomposition, and if the increased pressure exceeds the burst pressure of the tank, the tank will fail. Furthermore, heat input causes oxygen generation from thermal decomposition of peroxide and vapor generation, by boiling off the water-peroxide mixture. FMC further stated that because water is more volatile than peroxide, the hydrogen peroxide concentration in the tank will increase (although this may be compensated by water formation and peroxide loss from thermal decomposition). If the peroxide concentration reaches 74 percent by weight, the vapors in equilibrium with the liquid (40 percent by weight of peroxide) can detonate, if ignited, causing the tank car to fail. The results of FMC's mathematical heat transfer model show that tank cars containing hydrogen peroxide (having no less than a 7-percent outage) will not fail and such tank cars will meet the thermal protection criterion in Sec. 179.18 of this final rule for withstanding the effects of a pool-fire. Readers who are interested in a detailed discussion of Eka Nobel or FMC's fire studies on tank cars containing hydrogen peroxide, should refer to the comments filed in the RSPA Dockets Unit. Many commenters suggested a performance-based definition as a means to ensure the proper identification and packaging of thermally reactive materials, because, with increasing temperature, all materials will reach a stability limit. [[Page 49050]] These commenters suggested a performance-based definition that would include the polymerization potential; the rate of the chemical reaction (reaction kinetics); any highly exothermic reaction; the formation of gases, vapors, or fumes in a quantity sufficient to present a danger to human health and the environment; and any reactive by-products that could lead to over-pressurization of the tank. Commenters stated that a performance-based definition was the best way to ensure that the proper packaging requirements are attached to the appropriate hazardous materials. As evidenced from the comments, there is no single agreement on the best approach to identify these materials, nor to ensure the proper packaging requirements are assigned to these materials. Because of the multiplicity of these yet unresolved issues, the packaging requirements proposed in the NPRM for thermally reactive materials have not been adopted in this final rule. C. Tank-Head Protection In the NPRM, RSPA proposed several changes relating to tank-head protection. The proposal would require tank-head protection on tank cars, used for all Class 2 materials and for tank cars constructed from aluminum or nickel plate, when used to transport a hazardous material. RSPA included Division 2.2 in its proposal to reduce the violent rupture hazard and the asphyxiation potential to railroad workers or bystanders exposed to the product if these tank cars are punctured. The proposal to require full-head protection for tank cars constructed from aluminum or nickel plate is based on the vulnerability of the tank head to a puncture. The top-half of the tank head is vulnerable to puncture in a derailment. Existing tank cars with half-head protection were excluded, based on RSPA and FRA's regulatory analysis discussed later in this preamble. Consistent with these proposed changes, RSPA also proposed to eliminate a grandfather provision, in place since 1984, following publication of a final rule under Docket HM-175, that permits certain tank cars, with a capacity of less than 70 kiloliters (kl; 18,500 gallons), to continue in service without head protection. RSPA first introduced tank-head protection requirements after a series of railroad accidents in the late 1960s and early 1970s involving head punctures of tank cars (39 FR 27572 and 41 FR 21475). The requirements of, and criteria for, head protection were based on tests performed by FRA, the AAR, and the Railway Progress Institute (RPI) Tank Car Safety Research and Test Project in the early 1970s. In summary, these tests showed that head punctures, caused by over-speed impacts in railroad classification yards, generally occurred at speeds above 12 mph and often happened when a loaded tank car struck a standing empty tank car, causing the empty car to ``jump'' and ram its coupler into the head of the oncoming tank. A recent informal staff analysis of data on main-line accidents showed that objects, such as broken rails and couplers, may penetrate the top half of the tank head, indicating that head protection is essential, even though not 100 percent effective, in a train derailment. The NPRM referenced the recent FRA research on puncture resistance, which shows that puncture resistance is strongly influenced by impact location, head and jacket thickness, and insulation thickness. 5 Stated differently, research demonstrates that puncture resistance is an inter-related function of head thickness, insulation thickness, and jacket thickness, and that the concept of ``head protection'' must include more than just traditional ``head shields.'' Based on the results of this research, FRA expects that certain tank cars may meet the 29 kilometers per hour (18-mph) threshold for puncture-resistance, prescribed in Sec. 179.16 of this final rule, without further modification. \5\Coltman, M., & Hazel, M., Jr., Chlorine Tank Car Puncture Resistance Evaluation (1992), Federal Railroad Administration, Washington, DC (NTIS DOT/FRA/ORD-92/11). --------------------------------------------------------------------------- Tank cars currently equipped with half-head protection. Most commenters agreed that there is no need to require full-head protection on existing tank cars having only half-head protection. In comments filed in this docket, NTSB stated that the NPRM addressed many of their concerns, but noted the proposal failed to require existing tank cars used to transport Division 2.1 (flammable gas) materials, or other materials with extreme hazards, to be modified with full-head protection. Thus, these materials could be transported indefinitely in tank cars without full-head protection modifications. While we appreciate the concerns of NTSB, we are not able to establish a positive benefit/cost ratio by requiring modification of the existing tank car fleet, primarily because the half-head protection on existing cars is already about 95-percent effective. It is not credible to argue that greater safety gains are realized by mandating safety improvements on tank cars that currently have a 95-percent effective protection system, than by requiring improvements on tank cars without a head-protection system. The regulatory evaluation considered both approaches, with emphasis being placed on choosing the alternative offering maximum potential benefit to society, while imposing the least net cost. Based on the regulatory evaluation, this final rule does not require that existing half-head protection be removed and replaced with full-head protection. Head protection systems for existing tank cars with capacities less than 70 kl (18,500 gallons). RSPA received diverse comments in response to this proposal in the NPRM. One commenter agreed that class DOT 105 tank cars having capacities less than 70 kl (18,500 gallons) and transporting Division 2.1, 2.2, and 2.3 materials, should have full- head protection, unless already equipped with half-head protection. CMA supported the proposal to require full-head protection on newly built class DOT 105A tank cars, regardless of tank capacity, when used to transport a Division 2.1 or 2.3 material. The Reebie Associates report, submitted as part of CMA's comments, assumed that all tank cars would require head protection, except those that have a tank test pressure of 41.4 Bar (600 pounds per square inch [psi]). The Chlorine Institute agreed that head protection systems are now warranted for the transportation of chlorine, but recognized, based on FRA research and the accident history, that many tank cars currently used to transport chlorine meet the performance standard by virtue of a thick tank-head and a tank jacket. NTSB commented that RSPA should require tank-head protection, within 5 years, for all class 105 tank cars having capacities of less than 70 kl (18,500 gallons) when used to transport a Division 2.1 (flammable gas) material as proposed in Option B of the NPRM. RPI commented that, except for the nominal 41 kl (11,000-gallon) capacity tank cars, existing tank cars of less than 70 kl (18,500- gallon) capacity, transporting Division 2.1 materials or anhydrous ammonia, should have head-protection, but only half-head protection. RPI further commented that RSPA should exclude tank cars having a nominal capacity of 41 kl (11,000 gallons) from any head protection modification program, because most tank cars in this category are near or exceed 30 years of age; consequently, the economic life of the tank is nearing an end. RSPA and FRA believe that there is no longer a justification for excluding tank cars having a capacity less than 70 [[Page 49051]] kl (18,500 gallons) from the modification requirements. While CMA's report is not so optimistic on the use of DOT 105A500W specification tank cars, RSPA and FRA believe that most of these tank cars will meet the performance standard by virtue of their increased head thickness, insulation, and metal jacket. Because of the small number of tank cars in this category, and the small incremental cost to make such head protection modifications for those tank cars that do not otherwise meet the performance standard mandated by this rule, in this final rule RSPA is removing the 70 kl (18,500-gallon) exception for existing tank cars in current Secs. 173.314(c) and 173.323(c)(1). Further, while most commenters supported the 10-year modification program for existing tank cars, we agree with NTSB, that when these tank cars are used to transport Division 2.1 materials, a 5-year modification program (as proposed in Option B of the NPRM) will ensure that those cars presenting the greatest risk are modified first. Tank cars transporting materials in Division 2.2. A commenter stated that the proposal to require full-head protection for Division 2.2 gases is sound and should be finalized. Several other commenters disagreed with the proposal to require full-head protection for Division 2.2 materials. The Reebie Associates report, submitted by CMA, identified 467 Class 2 materials affected by the proposed rule, 11 of which are Division 2.2 materials. The report shows that shippers used 1,448 tank cars in 1992 to transport these Division 2.2 materials, as follows: ------------------------------------------------------------------------ Commodity Population ------------------------------------------------------------------------ Argon, refrigerated liquid................................ 2 Ammonia solutions......................................... 28 Bromotrifluoromethane..................................... 1 Carbon dioxide, refrigerated liquid....................... 1,016 Chlorodifluoromethane..................................... 145 Chlorotetrafluoroethane................................... 26 Chloropentafluoroethane................................... 37 Dichlorotetrafluoroethane................................. 164 Fertilizer, ammoniating solutions......................... 4 Trifluoromethane.......................................... 1 Xenon, refrigerated liquid................................ 24 ------------- Total................................................. 1,448 ------------------------------------------------------------------------ CGA opposed the full-head protection requirement for tank cars transporting carbon dioxide. CGA referenced the testimony presented by RPI at the January 6, 1994 public hearing concerning recent head impact tests that verified the adequacy of the current head protection system on DOT 105A500W specification tank cars. With regard to CMA's and CGA's comments, RSPA and FRA believe that most tank cars used for ``carbon dioxide, refrigerated liquid,'' meet the performance standard for head protection by virtue of their tank head thickness and metal jacket. Tank cars used for ``argon, refrigerated liquid,'' and ``xenon, refrigerated liquid,'' also meet the head performance standard by virtue of the authorized class DOT 113 tank car specification. These tank cars must have a minimum outer jacket tank head of not less than \1/2\-inch thick steel. See Sec. 179.400-8(d). A total of 1,042 tank cars, or 72 percent of the total Division 2.2 tank car population, are used to transport these three commodities. A commenter opposed tank-head protection for Division 2.2 materials stating, ``heavy walled tank and protective housing for the fittings is adequate for the transportation environment.'' The commenter also provided an in-house report using a computer model that claims the asphyxiation potential from a punctured Division 2.2 refrigerant gas tank car to be very low.'' Another commenter opposed applying head protection to tank cars transporting Division 2.2 refrigerant gases. This commenter stated that, in the past, DOT had judged a material based on its hazards under normal conditions of transport, and that in this rulemaking, DOT was over-assessing the potential for harm in a low-probability event. RPI supported full-head protection on new, insulated tank cars transporting Class 2 materials, but it opposed full-head protection for new non-insulated tank cars or for existing tank cars transporting these materials. We believe that even though the probability of an event occurring with these materials is low, safety concerns still need to be addressed, because the event may lead to high consequences, such as a large scale evacuation or an oxygen deficient atmosphere in a concentrated populated area. Taking the safety steps adopted in this final rule will mitigate these hazards. We also believe that the transportation risks associated with Division 2.2 gases are sufficient to require full-head protection for new tank cars, and for existing tank cars without head protection, when used to transport Division 2.2 materials. As noted above, this rule does not require existing tank cars equipped with half-head protection to be modified with full-head protection. RSPA and FRA are aware of industry concerns that the attachment of full-head protection to non- jacketed cars is a feature not yet proven by long service. Similar arguments were raised when head protection was first required almost two decades ago [HM-144; 42 FR 46306, September 15, 1977]. FRA is aware of companies with plans to attach full-head protection to their non- jacketed tank cars. As discussed later in this preamble, a phased-in 10-year modification program is provided for existing tank cars. Existing tank cars without head protection. Most commenters to the NPRM supported the need to modify existing tank cars to meet the current safety requirements. One commenter supported the need to modify existing tank cars constructed from aluminum plate with half-head protection, but believed full-head protection should be required when a proven full-head shield design is available. Another commenter suggested that DOT should specifically recognize that tank cars used in ``chlorine'' service meet the performance requirements for head protection and that DOT should not require any additional head protection for these tank cars. As stated in the NPRM, the benefits of head protection are real, predictable, and quantifiable. RSPA disagrees with commenters who state that full-head protection is not warranted. Where earlier rules required head protection on tank cars, it was a matter of recognizing the highest priority needs first. The question is not one of demanding low-priority, safety benefits, but the need to expand the safety base of hazardous materials transportation in tank cars. Further, the small additional cost of installing full-head protection on cars that now have no head protection system, as compared with adding only half-head protection, is justified on the basis of increased safety (see Chapter V of the Economic Impact Assessment and Regulatory Flexibility Analysis). In this final rule, RSPA requires existing tank cars that currently have no head protection, to have full-head protection installed when used to transport a Class 2 material. As explained below, RSPA is also requiring full-head protection for tank cars constructed from aluminum or nickel plate when used to transport hazardous material. Tank cars constructed from aluminum and from nickel plate. Commenters supported the need for head protection on tank cars constructed from aluminum or nickel plate, but not the full-head protection requirement proposed in the NPRM. Most commenters stated that there is no design available for the securement of full-head protection on tank cars without metal jackets. [[Page 49052]] One commenter stated that his company's new aluminum tank cars, constructed with greater tank shell and head dimensions than standard tank cars, offer greater protection without head protection. The commenter stated that further testing should be done and suggested that RSPA and FRA submit more evidence to support the need for this requirement. CMA supported requiring half-head protection for new tank cars constructed from aluminum or nickel plate, and requiring half-head protection for existing tank cars for certain hazardous materials. Several commenters requested that RSPA consider the characteristics of an individual Division 2.2 material, and that materials not subject to the HMR, and low hazard materials should be excluded. We realize that the use of good engineering practice and design specifications are needed to secure full-head protection to tank cars without metal jackets. Although there is no service experience for a full-head protection design on non-insulated tank cars, such designs are certainly not unreachable within the years ahead. In rulemaking proceedings under another docket [HM-144; 42 FR 46306, September 15, 1977] introducing half-head protection, commenters offered similar arguments regarding head protection, for which solutions were later found as a result of technological innovation. Currently, FRA is aware of several companies that are nearing completion on their full-head protection designs for aluminum and nickel tank cars. We, therefore, believe that the introduction of this requirement will not adversely affect industry. In this final rule, the use of full-head protection for all tank cars constructed from aluminum or nickel plate is required when used to transport a hazardous material. As discussed later in this preamble, RSPA has provided for a phased-in 10-year modification program. D. Thermal Protection Systems In the NPRM, RSPA proposed to require a thermal protection system for a Class 2 material when a thermal analysis of the tank car and lading shows that a release will occur other than through the safety relief valve when the tank car is subjected to either a 100-minute pool fire or a 30-minute torch fire. The current HMR require thermal protection for Division 2.1 (flammable gas) materials (with limited car capacity restrictions) and certain Division 2.3 (poison gas) materials. RSPA proposed to expand the thermal protection requirements to include Division 2.2 materials because, as stated by AAR, ``[a]t a chemical accident, there are generally two reasons for an evacuation, one is to protect the public from any toxic, poisonous, or noxious vapors or fumes generated by the product itself . . ., the second is to protect the public from thermal ruptures and the container debris that may be hurled from an incident site'' [Emergency Action Guides, p. VII]. RSPA also proposed to expand the thermal protection requirement to include all Division 2.3 materials. RSPA began to require the application of a thermal protection system on tank cars transporting Division 2.1 materials (flammable gases) or ``ethylene oxide'' (Division 2.3) after a series of major railroad accidents involving fires and ruptures of non-insulated pressure tank cars. The design of and criteria for thermal protection systems were based on tests performed by FRA at the U.S. Army Ballistics Research Laboratory in White Sands, New Mexico, and at the Transportation Test Center in Pueblo, Colorado. These tests revealed that a 127.2 kl (33,600 gallon) non-protected tank car filled with propane (Division 2.1) will rupture, with 40 percent of the lading remaining in the tank car, within 24 minutes after exposure to a pool- fire. Rupture occurs when the residual strength of the tank shell falls below the force generated by the vapor pressure of the lading exerted on the inside surface of the tank shell. Further testing by FRA demonstrated that a tank car filled with propane and equipped with a thermal protection system delayed the thermal rupture of the tank car for 94.5 minutes, by maintaining the shell temperature low enough to vent 98 percent of the lading through the safety relief valve. The current performance standard, requiring exposure to a 100-minute pool fire and a 30-minute torch fire, was chosen because it provides emergency response personnel time to assess the accident and to initiate remedial actions, such as evacuating an area. Division 2.1 (flammable gas) and 2.3 (poisonous gas) materials: Several commenters supported the need for a thermal protection system on tank cars transporting Division 2.1 or 2.3 materials, regardless of tank car capacity. The AAR and another commenter supported a thermal protection system for all Class 2 materials, unless a shipper could show that a release will not occur, other than through the safety relief valve, when the tank and lading are subject to a fire. RPI also concurred on the need for thermal protection for all Class 2 materials, but, except for Division 2.1, but did not support the high-temperature performance standard proposed in Sec. 179.18. RPI stated that most insulation materials (e.g., 4 inches of glass-fiber insulation) are adequate. In this regard, RSPA stated in the NPRM that many insulation materials also provide good thermal protection. These insulation materials, when analyzed with the tank and the lading, may show that nothing further needs to be installed on the tank car to achieve passage of the pool- and torch-fire performance tests. Research sponsored by FRA on urethane-foam and glass-fiber insulation systems show that urethane-foam insulation will pass the pool- and torch-fire requirements and that glass-fiber insulation will also pass both tests, provided the insulation is held in place with a plastic or wire scrim. Owners of tank cars with either of these systems, or another comparable system, may find that their thermal analysis of the tank car shows the presence of sufficient thermal protection to meet the performance standard. In this case, the tank car owner would have to verify only that the insulation material installed on the tank car is capable of passing the pool- and torch-fire verification or ``proof'' tests in Appendix B to Part 179 of this final rule. Owners may find that a tank car will pass the performance standard with only minor modifications, such as applying a thermal protection system to the manway nozzle. Also in the NPRM, RSPA stated that, in 1981, a joint effort between the Chlorine Institute and RPI-AAR Tank Car Safety Research and Test Project resulted in the development of an insulation system to protect a chlorine tank car involved in a fire. The insulation system developed maintains back plate (inside surface of the tank car shell) temperatures below 250.56 deg.C (483 deg.F). After reviewing the thermal resistance capabilities of the insulation system used on chlorine tank cars, RSPA incorporated it into the HMR in 1987. Readers should refer for more information to Docket HM-166U, entitled ``Transportation of Hazardous Materials; Miscellaneous Amendments'', 52 FR 13034, (April 20, 1987). Division 2.2 (nonflammable gas) materials. As noted earlier in the preamble discussion on tank-head protection for Division 2.2 materials, CMA commented that there were 1,448 tank cars allocated to Division 2.2 materials that had not already been captured in another service, such as PIH. Of those, ``argon, refrigerated liquid,'' ``carbon dioxide, refrigerated liquid,'' and ``xenon, refrigerated liquid,'' represent 1,042 tank cars, or 72 percent. CMA further commented that [[Page 49053]] almost 100 percent of the total would need retrofitting and that the overall economic impact of the new regulations on this group of tank cars amounts to $26.0 million for retrofitting and $2.59 million for higher lease rates and additional cars in the tenth year of the implementation period. With regard to the issues raised by CMA, this final rule does not contain any new thermal protection requirements for ``argon, refrigerated liquid,'' ``carbon dioxide, refrigerated liquid,'' or ``xenon, refrigerated liquid.'' Carbon dioxide is transported in DOT 105A500W tank cars equipped with two regulator valves, a reclosing pressure-relief device, a frangible disc, and an insulation system with good 
- **truncated:** true
- **body characters:** 251529