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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Molten Sulphur Rail Tank Car Loading and Unloading Operations: Leading Practices in Industry

Document Series
Other Reports
The Sulphur Institute
Subject Hazardous Materials
Hazardous Materials

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: 

  • Study Overview and Sulphur Properties
  • Safety Precautions
  • Loading Practices
  • Unloading Practices
  • Observations Regarding Leading Practices

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.

DOT is committed to ensuring that information is available in appropriate alternative formats to meet the requirements of persons who have a disability. If you require an alternative version of files provided on this page, please contact
Last updated: Thursday, July 31, 2014