L52281 Evaluating the Need for Loading Specifications for Highway Transportation of Line Pipe

Standards have been in place for many years providing procedures for the proper loading of line pipe for shipment by railroad and by vessel, namely, API Recommended Practice 5L1 and API Recommended Practice 5LW, respectively. These practices were developed in response to a recognized need to avoid excessive stresses in the transported pipe caused by unfavorable positioning of the pipe on cradles or supports combined with inertial loadings on the stacked pipe from railcar or vessel motion. The need for this effort became apparent as a result of hydrostatic test failures that occurred in newly constructed pipelines where the failure origins exhibited fatigue even though the pipe had not yet entered service, as well as in-service failures originating at shipping-damage defects that survived the commissioning hydrostatic test but enlarged while the line was in service. The scope of this study consisted of three phases. The first phase was to document the industry position with respect to line pipe transport. The second phase was to perform a detailed technical analysis of the susceptibility of line pipe to damage from inertial loadings during highway transportation. The third phase was to develop a prototype standard giving minimum specifications designed to avoid damage. The resulting work product can be used as a starting point by an appropriate standards-writing body for development of a specification in accordance with its standards development process.