Trench installation without sand bed
Increasing cost pressure is forcing many utilities to examine the necessity of costly sand bedding when installing new lines. If the excavated soil can be compacted, it can be reutilised for filling, instead of using sand. Of course, this presupposes a pipe system that can withstand the resultant loads. In rural regions, the possibility also exists of installing new pipelines at a tremendous rate using ploughing or milling installation techniques.
Dispensing with the sand bedding can result in the outer surface of newly installed pipelines becoming scratched (max. 10% of the pipe wall thickness permissible). Furthermore, stones can exert point loads or linear loads on the outer surface of the pipe over an extended duration – in addition to the regular operating loads, such as internal pressure, soil and traffic loads ? and thus cause damage. If pipe protection by means of a sand bed is dispensed with, the selected pipe system must be able to withstand the slight surface damage caused by scratches and, in particular, point loads, so that these do not result in stress-induced cracking.