The rail industry’s federal regulatory structure is complex, with varying levels of rules, regulations and standards. While most of the industry is regulated by standards applied by the Association of American Railroads (AAR) and certain safety regulations under the Federal Railroad Administration (FRA), railroad tank cars are unique, in that certain components fall under Pipeline and Hazardous Materials Safety Administration (PHMSA) hazmat regulations enforced by the FRA. Those regulations still reference AAR standards for technical and quality assurance program requirements, in addition to giving the AAR delegated authority for tank car design approval and oversight of repair and manufacturing facilities.
Federal rules mandate inspection of tank cars to ensure they meet the requirements for safe rail transportation. Standards and regular inspections ultimately help railroad operators limit the impact of accidents that pose a threat to human life and the environment. Although derailments and hazmat spills are rare (some 99.9% of chemical shipments reach their destinations safely, without incidents, according to FRA data and the AAR), it’s important for all railroad personnel to do their part to prevent even minor incidents, as all derailments have the potential to escalate. To prevent catastrophic incidents due to tank car derailments, regular inspection and predictive maintenance is essential to confirm structural integrity and preserve tank car longevity.
Risk Management in Practice
DOT’s hazmat regulations require that tank car owners maintain a qualification and maintenance program that specifies where, when, how and what to inspect certain components. These include the tank heads, shells, nozzles, saddles, sumps, certain service equipment and select safety systems. These parts are typically referred to as the “Hazmat Package.” Most of these inspections are performed by utilizing NDT (nondestructive testing).
NDT, also known as NDE (nondestructive evaluation), is analysis of material or equipment to evaluate its integrity without causing damage to its serviceability. NDT comprises 16 commonly recognized methods, with many consisting of numerous techniques. NDT methods and techniques are performed based on several factors, including material type, flaws size and orientation, accessibility, desired sensitivity and reliability.
Hazmat regulations recognize five NDT methods that can be utilized for structural integrity: visual testing (VT), liquid penetrant testing (PT), magnetic particle testing (MT), ultrasonic testing (UT) and radiographic testing (RT). Leak testing (LT) is required for service equipment. Other methods may be utilized on areas where no method is specified, such as infrared thermography (IR), which is frequently performed to verify insulation, and thermal protection is intact during qualification. When the original tank car qualification regulations were implemented in 1995 under HM-201, less than half of today’s NDT methods were available to inspectors at the time.
While hazmat regulations may specify what method to use, the AAR M1002 “Specification for Tank Cars” identifies procedural requirements for common methods as well as qualification and certification requirements of NDT personnel.
Inspection methods are continuously evolving, as new technologies such as artificial intelligence (AI), 3D imaging and robotic applications are integrated into established methods. Since creation of current regulations, new methods have emerged that can offer a higher level of safety and increased reliability. At the same time, tank car owners, which are not usually the railroad companies themselves, can apply for an alternative inspection plan or special permit to incorporate these new methods into their qualification programs.
An Ounce of Prevention
As tank cars age, they can become susceptible to failures. It is important for owners to take proactive measures to prolong their longevity by selecting the right NDT method and technique that will provide a suitable level of sensitivity and reliability to find flaws before they fail in service. This proactivity can potentially prevent accidents or the release of dangerous commodities.
Hazmat regulations should be modernized to take more of a performance-based approach, which should specify what a selected NDT method should be able to achieve, rather than specifying the method itself. This would eliminate the need to apply for an alternative inspection plan or special permit to use an unspecified NDT method, which can be a very lengthy process.
Even legacy NDT methods have become increasingly complex as equipment has become more sophisticated. Combined with new NDT methods and techniques, the need for comprehensive training and thorough testing of NDT technicians is imperative. Tank car manufacturing as well as repair and qualification facilities should ensure their in-house programs are robust enough to address these issues. Alternatively, NDT technicians may be trained and tested directly by third party organizations such as the American Society of Nondestructive Testing (ASNT).
Today, tank car builders and owners are improving design and structure of tank cars to improve durability and reduce susceptibility to damage. The National Transportation Safety Board (NTSB) is striving for stricter inspection and predictive maintenance standards to protect human life and the environment. With routine inspection using appropriate NDT methods performed by properly trained and tested personnel, the rail industy can significantly reduce the potential for incidents.
Jason Riggs is Vice President of the American Society of Nondestructive Testing (ASNT) and Vice President of Technical Services & Regulatory Affairs at Marmon Rail.
