API RP 3000:2014 provides guidance on the material characterization, transport classification, and quantity measurement for overfill prevention of petroleum crude oil (crude oil) for the loading of rail tank cars. Guidance on the documentation of measurement results is also provided. The criteria for determining the frequency of sampling and testing of petroleum crude oil are identified for transport classification. This document applies only to petroleum crude oil classified as Hazard Class 3—Flammable Liquid under the U.S. Code of Federal Regulations (CFR) at the time of publication.