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Miscellaneous Hazmat Papers
Papers and reports are listed by their document titles starting with the most recent published document. Click on the title under "Report" for an electronic copy of the document, if available.
Notice and Disclaimer: These documents are disseminated under the sponsorship of the United States Department of Transportation in the interest of information exchange . Any opinions, findings and conclusions, or recommendations expressed here do not necessarily reflect the views or policies of the United States Government, nor does mention of trade names, commercial products, or organizations imply endorsement by the United States Government. The United States Government assumes no liability for the content or use of the material contained in these documents.
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Molten Sulphur Rail Tank Car Loading and Unloading Operations: Leading Practices in Industry |
The Sulphur Institute (TSI) has coordinated with the US Department of Transportation (DOT), Federal Railroad Administration (FRA) to observe, review, and provide a summary of procedures for loading and unloading molten sulphur rail tank cars and identify leading practices and opportunities for information sharing to enhance operations. These observations have led to development of this document on reducing potential for solid sulphur residue on the exterior of rail tank cars and ideas to improve practices and procedures for loading and unloading operations. The Institute conducted a confidential survey of existing member company locations, including average number of molten sulphur rail tank cars loaded or unloaded per day, at several operating facilities. From this survey, sites were selected and solicited for peer review. Companies were contacted to assess their interest in participating in this study. Copies of loading and unloading procedures were requested and received from these and other interested companies. Institute staff visited two loading, one transloading, and three unloading facilities to observed and collect data on possible origins of sulphur residue on the exterior of rail tank cars. These data have allowed TSI to identify potential causes, analyze associated trends, and provided an opportunity for industry to share practices and reduce molten sulphur residue on exterior surfaces of rail tank cars. The sulphur industry’s goal is to load, transport, and unload sulphur in as safe and effective manner as possible. The Institute received an FRA grant to conduct a study and share leading practices for improving efficiency and safety of loading and unloading molten sulphur to and from rail tank cars. This Molten Sulphur Rail Tank Car Loading and Unloading Operations study is an effort to share a variety of leading practices collected and aggregated from several facilities within the United States. This summary report provides the sulphur industry multiple examples of loading and unloading practices from which to select those most appropriate for their facility. In addition, this summary report provides general information about properties of sulphur and available references for safe handling. The focus of the document is to address common issues faced when a worker is performing standard operating procedures around the manway when loading or unloading. Additional information regarding bottom outlet valves, as is necessary to the loading / unloading of the rail tank car is provided, however, is largely referenced in Section 6.0. Please refer to these resources for additional information. This document references the following aspects of loading / unloading molten sulphur:
This study is neither a complete and comprehensive set of rail tank car loading and unloading methodologies, including worker safety procedures, nor meant to establish any standard or industry practice. Each particular location may require the use of additional, or different, precautions for loading and/or unloading operations to be performed safely, as each site may have unique attributes. |
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Guidelines for Hinged and Bolted Manway Assembly (Renewable Fuels Association) |
This guideline document is in response to an increased need for an engineering standard for the inspection, maintenance, and securement of a hinged and bolted manway to ensure leak-free performance. Eliminating leaks around a hinged and bolted manway protects against the risks to life, property, and the environment in intrastate, interstate, and foreign commerce. By following this document, an operator can achieve a consistent, high-level, process of assembling a hinged and bolted manway. This document is a result of a grant issued by the Federal Railroad Administration to the Renewable Fuels Association to provide an educational tool for field personnel. The Renewable Fuels Association greatly appreciates and recognizes the following contributors: Watco Compliance Services, VSP Technologies, and Salco Products, Inc. |
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In 2005, SAFETEA-LU required FRA to conduct a comprehensive analysis to determine the impact resistance of the steels in the shells of pressurized tank cars constructed prior to 1989. To address this SAFETEA-LU requirement and NTSB's recommendation, the Southwest Research Institute (a subcontractor to FRA's contractor, the Volpe Center) has produced a final research report on its work in basic material characterization, tensile property evaluation, chemical makeup, and sharpy v-notch toughness at three different temperatures of the steels in the shells and heads of pre-1989 tank cars. |
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Engineering Analysis for Railroad Tank Car Head Puncture Resistance |
This paper describes engineering analyses to estimate the forces, deformations, and puncture resistance of railroad tank cars. Different approaches to examine puncture of the tank car head are described. One approach is semi-empirical equations to estimate the velocity at which puncture is expected to occur. Other approaches apply elastic-plastic finite element analysis. The results from these approaches are compared with experimental data from impact tests, and are shown to provide reasonable estimates of impact forces. |
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This paper describes a planar or two-dimensional model to examine the gross motions of rail cars in a generalized train derailment. Three coupled, second-order differential equations are derived from Newton’s Laws to calculate rigid-body car motions with time. Car motions are defined with respect to a right-handed and fixed (i.e., non-rotating) reference frame. The rail cars are translating and rotating but not deforming. Moreover, the differential equations are considered as stiff, requiring relatively small time steps in the numerical solution, which is carried out using a FORTRAN computer code. Sensitivity studies are conducted using the purpose-built model to examine the relative effect of different factors on the derailment outcome. These factors include the number of cars in the train makeup, car mass, initial translational and rotational velocities, and coefficients of friction. Derailment outcomes include the number of derailed cars, maximum closing velocities (i.e., relative velocities between impacting cars), and peak coupler forces. Results from the purpose-built model are also compared to those from a model for derailment dynamics developed using commercial software for rigid-body dynamics called Automatic Dynamic Analysis of Mechanical Systems (ADAMS). Moreover, the purpose-built and the ADAMS models produce nearly identical results, which suggest that the dynamics are being calculated correctly in both models. |
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This paper describes analyses of a railroad tank car impacted at its side by a ram car with a rigid punch. This generalized collision, referred to as a shell impact, is examined using nonlinear finite element analysis (FEA) and threedimensional (3-D) collision dynamics modeling. Moreover, the analysis results are compared to full-scale test data to validate the models. Commercial software packages are used to carry out the nonlinear FEA (ABAQUS and LS-DYNA) and the 3-D collision dynamics analysis (ADAMS). Model results from the two finite element codes are compared to verify the analysis methodology. Results from static, nonlinear FEA are compared to closed-form solutions based on rigid-plastic collapse for additional verification of the analysis. Results from dynamic, nonlinear FEA are compared to data obtained from full-scale tests to validate the analysis. The collision dynamics model is calibrated using test data. While the nonlinear FEA requires high computational times, the collision dynamics model calculates gross behavior of the colliding cars in times that are several orders of magnitude less than the FEA models. |
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Three recent accidents involving the release of hazardous material have focused attention on the structural integrity of railroad tank cars: (1) Minot, ND, on January 18, 2002; (2) Macdona, TX, on June 28, 2004; and (3) Graniteville, SC, on January 6, 2005. Each of these accidents resulted in fatalities. Research is being conducted to develop strategies for improving railroad tank cars so they can maintain tank integrity in severe accidents. A collaborative effort called the Next Generation Rail Tank Car (NGRTC) Project intends to use these research results to help develop improved tank car designs. Dow Chemical Company, Union Pacific Railroad, and Union Tank Car Company are the industry sponsors of the NGRTC Project. The Federal Railroad Administration (FRA) and Transport Canada participate in the NGRTC project through Memoranda of Cooperation. FRA and the Pipeline and Hazardous Materials Safety Administration intend to use these research results to support rulemaking. |
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Developing Strategies for Maintaining Tank Car Integrity During Train Accidents |
Accidents that lead to rupture of tank cars carrying hazardous materials can cause serious public safety hazards and substantial economic losses. The desirability of improved tank car designs that are better equipped to keep the commodity contained during impacts is clear. This paper describes a framework for developing strategies to maintain the structural integrity of tank cars during accidents. |
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Analysis of Impact Energy to Fracture Unnotched Charpy Specimens Made From Railroad Tank Car Steel |
This paper describes a nonlinear finite element analysis (FEA) framework that examines the impact energy to fracture unnotched Charpy specimens by an oversized, nonstandard pendulum impactor called the Bulk Fracture Charpy Machine (BFCM). The specimens are made from railroad tank car steel, have different thicknesses and interact with impact tups with different sharpness. The FEA employs a Ramberg-Osgood equation for plastic deformations. Progressive damage and failure modeling is applied to predict initiation and evolution of fracture and ultimate material failure. Two types of fracture initiation criterion, i.e., the constant equivalent strain criterion and the stress triaxiality dependent equivalent strain criterion, are compared in material modeling. The impact energy needed to fracture a BFCM specimen is calculated from the FEA. Comparisons with the test data show that the FEA results obtained using the stress triaxiality dependent fracture criterion are in excellent agreement with the BFCM test data. |
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This paper describes a probabilistic approach to estimate the conditional probability of release of hazardous materials from railroad tank cars during train accidents. Monte Carlo methods are used in developing a probabilistic model to simulate head impacts. The model is based on the physics of impact in conjunction with assumptions regarding the probability distribution functions of the various factors that affect the loss of lading. These factors include impact velocity, indenter size, tank material, tank diameter, effective collision mass, and tank thickness. Moreover, each factor is treated as a random variable characterized by its assumed distribution function, mean value, and standard deviation (or variance). Reverse engineering is performed to back-calculate the mean values and standard deviations of these random variables that reproduce trends observed in available accident data. The calibrated model is then used to conduct a probabilistic sensitivity analysis to examine the relative effect of these factors on the conditional probability of release. Results from the probabilistic sensitivity analysis indicate that the most significant factors that affect conditional probability of release are impact velocity, effective collision mass, and indenter size. |
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Modeling the Effect of Fluid-Structure Interaction on the Impact Dynamics of Pressurized Tank cars |
This paper presents a computational framework that analyzes the effect of fluid-structure interaction (FSI) on the impact dynamics of pressurized commodity tank cars using the nonlinear dynamic finite element code ABAQUS/Explicit. There exist three distinct phases for a tank car loaded with a liquefied substance: pressurized gas, pressurized liquid and the solid structure. When a tank car comes under dynamic impact with an external object, contact is often concentrated in a small zone with sizes comparable to that of the impacting object. While the majority of the tank car structure undergoes elasticplastic deformations, materials in the impact zone can experience large plastic deformations and be stretched to a state of failure, resulting in the loss of structural integrity. Moreover, the structural deformation changes the volume that the fluids (gas and liquid) occupy and consequently the fluid pressure, which in turn affects the structural response including the potential initiation and evolution of fracture in the tank car structure. |
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Analysis of Railroad Tank Card Shell Impacts Using Finite Element Method |
This paper examines impacts to the side of railroad tank cars by a ram car with a rigid indenter using dynamic, nonlinear finite element analysis (FEA). Such impacts are referred to as shell impacts. Here, nonlinear means elasticplastic material behavior with large deformations. Several computational issues are addressed. The dynamic response of the shell structure coupled with the sloshing response of fluid inside the tank is characterized through various mesh formulations. Puncture of the tank is calculated using a material failure criterion based on the general state of stress in the shell structure in terms of stress triaxiality. The FEA models were verified and validated in previous work. In the present work, the verified and validated FEA framework is applied to examine the effect of various factors on the structural response of the tank. These factors include shell thickness and indenter geometry. |
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Update on Ongoing Tank Car Crashworthiness Research: Predicted Performance and Fabrication Approach |
Research is currently underway to develop strategies for maintaining the structural integrity of railroad tank cars carrying hazardous materials during collisions. This research, sponsored by the Federal Railroad Administration (FRA), has focused on four design functions to accomplish this goal: blunting the impact load, absorbing the collision energy, strengthening the commodity tank, and controlling the load path into the tank. Previous papers have been presented outlining the weight and space restrictions for this new design, as well as the approach being taken in developing the design. The performance goals for the new car have also been outlined. A key goal for the new design is the ability to contain its lading at four times the impact energy of the baseline equipment. |
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Improved Tank Car Design Development: Ongoing Studies on Sandwich Structures |
This paper describes engineering studies on improved tank car concepts. The process used to formulate these concepts is based on a traditional mechanical engineering design approach. This approach includes initially defining the desired performance, developing strategies that are effective in meeting this performance, and developing the tactics for implementing the strategies. The tactics are embodied in the concept. The tactics and concept evolve through engineering design studies, until a design satisfying all of the design requirements is developed. Design requirements include service, manufacturing, maintenance, repair, and inspection requirements, as well as crashworthiness performance requirements. |
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Mechanical Properties of Tank Car Steels Retired from the Fleet |
This paper describes a laboratory testing program to examine the mechanical properties of steel samples obtained from tank cars that were retired from the fleet. The test program consisted of two parts: (1) material characterization comprised of chemical, tensile and Charpy V-notch (CVN) impact energy and (2) high-rate fracture toughness testing. |
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Semi-Analytical Approach to Estimate Railroad Tank Car Shell Puncture |
This paper describes the development of engineering-based equations to estimate the puncture resistance of railroad tank cars under a generalized shell or side impact scenario. Resistance to puncture is considered in terms of puncture velocity, which is defined as the impact velocity at which puncture is expected to occur. In this context, puncture velocity represents a theoretical threshold limit. A given object striking the side of a tank car at an impact speed below the threshold velocity is not expected to penetrate the commodity-carrying tank. This definition for puncture velocity is similar to that for ballistic limit velocity, which is used to measure a target’s ability to withstand projectile impact in military applications. |
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Deformation Behavior of Welded Steel Sandwich Panels under Quasi-Static Loading |
This paper summarizes basic research (i.e., testing and analysis) conducted to examine the deformation behavior of flat-welded steel sandwich panels under two types of quasi-static loading: (1) uniaxial compression; and (2) bending through an indenter. The objectives of these tests were to: (1) confirm the analytical and computational (i.e., finite element) modeling of sandwich structures, (2) examine the fabrication issues associated with such structures (e.g., material selection and welding processes), and (3) observe the deformation behavior and local collapse mechanisms under the two different types of loading. In addition, the uniaxial compression tests were performed to rank or screen different core geometries. Five core geometries were examined in the compression tests: pipe or tubular cores with outer diameters equal to 2, 3, and 5 inches; a 2-inch square diamond core; and a double-corrugated core called an X-core with a 5-inch core height. |
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This paper describes engineering analyses of a railroad tank car impacted at its head by a rigid punch. This type of collision, referred to as a head impact, is examined using dynamic, nonlinear finite element analysis (FEA). Commercial software packages ABAQUS and LS-DYNA are used to carry out the nonlinear FEA. The sloshing response of fluid and coupled dynamic behavior between the fluid inside the tank car and the tank structure are characterized in the model using both Lagrangian and Eulerian mesh formulations. The analyses are applied to examine the structural behavior of railroad tank cars under a generalized head impact scenario. Structural behavior is calculated in terms of forces, deformations, and puncture resistance. Results from the two finite element codes are compared to verify this methodology for head impacts. In addition, FEA results are compared to those from a semi-empirical method. |
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This report summarizes the results of a detailed stress analysis and fatigue assessment of two stub sill tank car designs often used for the transport of hazardous materials. This particular class of railroad cars has come under scrutiny by the Federal Railroad Administration in recent years because of occasional stub sill tank car failures that have led to the release of hazardous materials. The United States and Canadian governments asked the tank car industry to inspect at least 1,100 tank cars, perform a theoretical analysis of the stub sill problem, and then evaluate the inspection results compared with theoretical calculations. |