Economics – Internal coating for Cost reduction

Site last update July 15th_2021

Keywords: economics pipeline cost diameter pressure velocity flowrate reynolds number internal coating surface structuration

The cost of a pipeline depends on a very large number of parameters, including the flow characteristics. Among these parameters, we may quote the quality of the steel, the diameter and pressure of the pipeline as well as the power of the re-compression stations. The first three parameters are of course linked together defining the maximum pressure of the pipeline. This pressure is chosen so as to allow an optimum choice in terms of flow velocity, pressure drops and size of the pipeline taking into account the composition of the gas and its flow rate. The investment cost being considerable, it is important to minimize as much as possible the pressure losses. For a given pipeline configuration, a reduction in pressure losses may be obtained in two different ways with a degree of performance associated with the complexity of the technology used.

Internal coating – Conventional application

An internal pipe coating with a minimum thickness and of a coating of a suitable type in order to obtain the minimum surface deformations (roughness and undulation – See chapter 1 – Flow friction). The associated gain can vary from a few percent to ten percent depending on the quality of the uncoated steel in relation with the quality of the gas transported (uncoated steel with performance possibly degrading over time) and the Reynolds number of the pipe (or thickness viscous layer).

Internal coating – Surface structuration

An internal coating with a structured surface of a three-dimensional shape (see chapter 1). An additional gain of 15% can be obtained by comparison with a smooth surface. This gain is independent of the Reynolds number value of the pipeline, only the dimensions of the structures change according to the Reynolds number. It is important to note that since the Reynolds number does not change between the entry and the exit of the pipeline, the dimension of the structures is invariable inside this pipe.

The technico-economical study takes into account the contribution of these two technologies to a gas pipeline.

This section will be completed later