The main concern regarding to the restart operations for production wells in oil and gas systems is the forecast of minimum pressure needed to overcome the gel strength, i.e. the pressure which generates a wall stress higher than the yield stress of the gelled oil. The petroleum accumulations around the world have raised big issues regarding flow assurance aspects, especially in some ultra-deep water scenarios. In these cases, when the oil presents unusual high values for the Wax Appearance Temperature (WAT) and even for the yield stress, the flow restart procedure can be an issue, after shutdown times of the oil production. Usually, the thixotropic models applied for start-up flow are defined by a Bingham-like stress equation whose yield stress depends on a structure parameter (lambda), following Houska assumptions. This parameter is a non-negative scalar number that represents the structuring level of the material inside the pipeline. The structure parameter is governed by an evolution equation that considers a build-up term and a breakdown term. The main objective of this work is to evaluate the relationship between the parameters of the constitutive equations for Houska and SMT models (dimensionless coefficients of the evolution equations for the structure parameter) and the representativeness of the simulation results obtained by these models, regarding times for the production stabilization after a restart, delay times and yield stresses, when compared to experimental data.