Proposed method of leakage identification uses a parametric model in the form of signals phase shift (φ). Signals from the test stand will be used: r1, r2 - signals from the corrective elements connected to the tested pipeline, pressure signals x, mass flow y and simulated mass flow yw. For these signals, their auto and cross power spectral densities are determined: Sxx, Syy, Srr, Sxy, Sxr, Syr, which are the basis to determine spectral transfer functions described as the relations between these signals and next the phase shifts (φ). Thanks that, we get a large set of transfer functions, hence a large set of phase shifts between the measured.