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1. 2. Typical inspection areas for qualifying tank cars are as follows:Visual inspection of the interior and exterior of the tank. These inspections include inspection of tank welds, shells and heads for abrasion, corrosion, cracks, dents, distortions, weld defects, or any other condition that would make the tank unsafe for transportation.
      1. Structural integrity inspection using one or a combination of 6 methods Liquid Penetrant (PT), Magnetic Particle (MT), Radiographic Testing (RT), Ultrasonic Testing (UT), Direct and/or Remote Visual Testing (VT/RVT), and Acoustic Emission (AE). The inspection involves a structural integrity inspection of all transverse fillet welds and termination of longitudinal fillet welds greater than 0.25 inches (0.64 cm) within 4 feet (121.92 cm) of the bottom longitudinal centerline of the tank car. The structural integrity inspection also includes an inspection of tank shell butt welds within 2 feet (60.96 cm) of the bottom centerline that have structural discontinuities and/or terminations of reinforcements within 12 inches (30.48 cm) of the weld.
      2. Thickness check of the tank shell, heads, sumps, domes, and nozzles. The minimum allowable thickness should be mandated and will vary with car design. This check may not be required for tank cars that have a lining/coating program.
      3. Safety system inspection on all safety equipment (e.g., thermal protection, safety relief devices, and nozzle protection systems) to verify functionality and presence. 
      4. Lining and coating inspection. A general inspection of interior coatings and linings, if applicable, are in proper conditions.
      5. A leak test of service equipment (e.g., tank, service equipment, and closures) is performed to ensure they are leak-free.

Probability of detection (POD) studies have been funded by the FRA. One of such studies, completed in April 2021, titled “Analysis of Historical Non-Destructive Evaluation Probability of Detection Data for Railroad Tank Cars,” demonstrated that a group of inspectors with various levels of experience and certifications performing inspections using CFR-approved NDT methods were not capable of achieving or approaching a 90-percent probability of detection (POD) with 95-percent confidence (90/95 POD) for fatigue cracks in butt weld test panels. Evaluation of the fillet weld data showed mixed results, but only the magnetic particle testing (MT) method reached 90/95 POD. A portion of their summary is stated below:

“Researchers strongly recommend a refresher training course especially if an inspector is new to a company. All inspectors should be trained and capable to detect both manufacturing defects and fatigue related cracks, not just one or the other. The NDT research team’s observations during these inspections, and evaluations of results using DOEPOD, detected significant variations in training procedures for inspectors among the industry. Researchers recommend that adequate specialized training on all CFR-approved NDE methods is necessary for personnel inspecting tank cars, regardless of the manufacturing or revenue service location. Also, the DOEPOD analysis determined that a more thorough calibration step should be followed and written into the procedure for each company. This includes performing a calibration using the type of material being inspected instead of calibration blocks.“

How would your inspectors perform in a POD study? Premier NDT Resources can be a great resource and partner in updating, modifying, or maintaining your NDT program locally and nationally. We can bolster any inspection program with custom training and procedures to fill potential knowledge gaps.