Abstract: A method and apparatus for locating leaks at an undetermined location in a section of pipeline of known length. Standard pressure vessels of relatively small volume are connected to respective ends of the pipeline section through valves. The pipeline is closed at each end and the valves into the standard pressure vessels are opened. Fluids are placed in the pipeline under a pressure. The valves to both of the standard pressure vessels are simultaneously closed, isolating each of the standard pressure vessels from the pipeline section so as to maintain the pressure vessels at substantially the same level as at the time of closing. The differential pressure between each end of the pipeline and its respective standard pressure vessel is then continuously monitored and recorded in real time measurements. The location of a leak is determined by solving an equation, based on the equilibrium equation and real time measured differential pressure values at each end of the pipeline.