Steel Pipe Design

This chapter covers the following topics as they relate to the direct steerable pipe thrusting method of trenchless steel pipe installation: installation related axial, bending, hoop, torsional, and combined stresses; installation related pipe buckling evaluation and considerations; allowable thrust force calculation; operational stresses; and pipe coating considerations. As the steel pipe is thrust through the ground, stresses are induced in the pipe that must be assessed to avoid overstressing the pipe and yielding of the steel. If using the conventional Euler buckling theory as described, the relatively long unbraced lengths of thrust pipe typically predict buckling at axial loads that are much lower than are necessary to install the pipe. The design engineer should factor the thrust force estimate in accordance with their knowledge of the geotechnical conditions at the site, capacity of the pipe thruster, their experience, and other considerations.