The test requirements contained in the standard test method for drop-weight testing, the ASTM Method for Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels (E 208-81), generally limit its applicability to flat products or to products with at least one flat surface; this is done because of the shape of the standard test specimens and the need for the tension surface of the specimen to be an as-fabricated surface. Difficulties arise in the application of ASTM Method E 208-81 to steel products whose fabricated shapes are not flat, for example, piping and pressure vessels. For products with curved surfaces, some of the testing requirements must be violated; these include keeping the as-fabricated surface as the tension surface, uniform specimen thickness, a flat compression surface, and uniform stress on the tension surface. In this study, the nil-ductility transition (NDT) temperature was determined as a function of test specimen geometry for two carbon/manganese structural steel grades. The specimens were extracted from the head plates of railroad tank cars and were curved in two orthogonal directions. The sensitivity of the test results to variations in test specimen geometry has been determined as is reported here.