Stokes, Potter, Muhl, Acland
# 2001 Munich
Research indicates that the scoring of polyethylene pipes that can occur during directional drilling operations in clay soils will not exceed the specification of 10% pipe wall scoring depth. However, a higher level of damage may occur in different types of soils from these operations. Further investigations from samples taken from the different soil types will be necessary to determine the likely range of scoring that can occur. Techniques used by different contractors in undertaking the work are also likely to reveal different scoring patterns. A further statistical analysis of samples of pipe from different contractors’ sites, with a statement of methodology applied, will identify the techniques least likely to incur cause damage to the PE pipe. For pipe bursting operations, a greater degree of scoring takes place. The comparison of the level of scoring between 90 and 180 mm pipes is not in proportion to the pipe diameter and suggests that a minimum wall thickness of pipe should be specified to provide a high level of confidence that the specifications of damage will be maintained. As with directional drilling, the contractor’s technique could well have a significant effect on the degree of scoring incurred. A more detailed study will be necessary to formulate the preferred methodology. Pipes produced with a protective polypropylene layer have been shown to provide a very high level of protection of the inner surface.