The effect of downstream perforated blanket on the safety against piping in heading-up structures

This paper presents the results of an experimental study on the effect of using a perforated blanket downstream the aprons of heading-up structures with different scenarios of blanket length with different Perforation ratio and different holes diameter, presence of different cutoffs and different series of heading up on the safety against piping. It was found that piping index (Pe) is governed by perforation ration (PR), relative hole diameter (D/Lb), ratio of length of the blanket to length of the apron (Lb/La), head difference between upstream and downstream structure and the depth of downstream cutoff.