Methods of pipeline construction in arctic and subarctic regions

摘要

Methods of pipeline construction in arctic and subarctic regions and apparatus for carrying out those methods are disclosed. Following the disclosed methods, summer-constructed fabrication yards are established at locations along the pipeline right-of-way spaced at intervals of 100 to 150 miles. Each summer-constructed fabrication yard is regarded as being at or close to the center of its associated pipeline division, which is approximately 100 to 150 miles in length. Each fabrication yard comprises a group of summer-constructed buildings adapted for carrying out the steps in fabricating a pipe section, including quality control, X- ray, hydrostatic testing, external coating, final inspection, and river coating and weighting, along with yard facilities for moving elongated (e. g., 2500 foot) pipe sections from place to place during their fabrication, inspection, coating, etc. PP In the winter following the summer in which each pipe section is fabricated it is towed to its place of installation over a working snow pad or snow road following the pipeline right-of-way, for instance, by a pair of large tow tractors operating in tandem and provided with servo-controls by which one tow tractor operator in the front tractor can operate both tractors. The sensors or sensing instruments mounted on or in the pipe section in the fabrication yard during summer are cabled to indicating instruments in the oversized cab of the lead tow tractor, where they can be constantly observed by the controller or crew chief to assure that while in transit the pipe section undergoes no bend less than its permissible roped radius of curvature. The forward end of the pipe section being towed into place is mounted on a nose sled which also bears a compressor and air heater for the purpose of maintaining an elevated temperature inside the hermetically sealed pipe section.PP When a pipe section is being moved from the summer fabrication yard to its winter place of installation over a snow road a number of sideboom tractors (e.g., ten) accompany the pipe section, guiding respective portions of it in special roller cradles which are equipped with pipe-gripping means or brakes remotely controlled by the respective sideboom operators, so that the sideboom tractors can instantly grasp their associated pipe sections to assist in towing or prevent uphill or downhill "runaway".