Pipeline gauging vehicles

Claim 1

A pipeline gauging vehicle comprising: (a) an axially extending support structure; (b) at least one resilient driving cup mounted around the support structure so as to contact the interior wall of the pipeline and thus provide a pressure differential across the driving cup which will propel the vehicle along the pipeline; (c) at least two first monitoring arrangements located at axially spaced positions on the support structure; (d) each first monitoring arrangement consisting of at least three detecting elements located at circumferentially spaced positions around the support structure and at a predetermined radial distance from the longitudinal axis of the vehicle; (e) the axial spacing of the first monitoring arrangements and the radial location of their individual detecting elements being commensurate with a minimum radius of curvature of bends in the pipeline which the vehicle needs to negotiate when travelling through the pipeline; and (f) a plurality of second monitoring arrangements mounted at axially spaced positions along the support structure; (g) each second monitoring arrangement having detecting portions radially spaced from the longitudinal axis of the vehicle by a distance commensurate with a predetermined minimum radial distance from the interior surface of the pipeline which must be clear when the vehicle is travelling through the pipeline; (h) whereby the detecting portions engage the interior surface of the pipeline and provide an indication when said minimum radial distance is exceeded.