ABSTRACT
When either a high pressure or a high vacuum is used for pneumatic conveying, it is generally recommended that the pipeline should be stepped to a larger bore part way along the length of the line at least once. This is the case whether the material is being conveyed in dilute or dense phase, and whether the pipeline is long or short. Stepping of the pipeline is particularly recommended if the material being handled is either abrasive or friable. Problems of both erosive wear and particle degradation increase markedly with increase in velocity and so stepping the pipeline can have a very significant effect on limiting conveying air velocity values, and hence in minimizing the magnitude of erosion and degradation.
