Effects of surface modifications on wear mechanism in pneumatic conveying pipelines

Pneumatic conveying is a well-established method for transportation of granular materials in many industries. As many of these industries handle hard and abrasive materials, wear has been a serious issue for them for many years. Pipeline failure due to wear is a major cause for unplanned shutdown of plants costing large amounts in maintenance as well as lost production. As the problem became more acute for many industries due to stringent environmental and safety legislations, need for a predictive tool for pipeline failure has been recognised. Predictive models can provide necessary information to the plant managers and operators that can help them to avoid unplanned plant shutdowns. Existing wear models can predict material loss from a surface based on wear mechanisms and materials properties. Recent studies showed that the wear mechanism in low velocity areas of the pipeline is dictated by surface modification and formation of transfer film on the surface. This paper addresses the complexities and associated wear mechanisms that need to be understood before a successful predictive model can be developed. Surface modification and wear mechanisms in pneumatic conveying pipelines have been studied using scanning electron microscope (SEM). Brittle failure of surface layer has been recognised in both alumina and fly as conveying pipelines. Energy dispersive spectroscopy (EDS) has been used to study the elemental compositions of the surface layers removed through cracking and delamination. It was discovered that the constituents from the conveying materials are responsible for the surface modification which causes material removal through brittle mechanism.