method for determining the wall thickness of a pipe joint for use in an underwater pipeline, pipe joint, underwater pipe and method for determining a hydrostatic collapse pressure

摘要

a method for determining the minimum wall thickness of a pipe joint for use in an underwater pipeline comprises the steps of: i) determining an inner diameter of the pipe joint; ii) determine a minimum allowable hydrostatic pressure at the depth at which the pipe joint is to be used; iii) determine a target wall thickness for the pipe joint, the target wall thickness corresponding to the internal diameter and the minimum allowed hydrostatic pressure; iv) fabricating a plurality of preliminary pipe joints having the internal diameter and thickness of the target wall; v) to carry out external pressure collapse tests, resulting in data representative of hydrostatic collapse pressures in which the plurality of preliminary pipe joints collapse; vi) determine a probability distribution corresponding to the data based on a statistical tail model derived from the theory of extreme values; vii) determine, from the probability distribution, a hydrostatic collapse pressure occurring with a probability of 10-5 or less; and, viii) determine a wall thickness of the pipe joint corresponding to the internal diameter and hydrostatic collapse pressure.