METHODS OF PIPELINE CONSTRUCTION IN ARCTIC AND SUBARCTIC REGIONS AND APPARATUS FOR CARRYING OUT SAME

摘要

METHODS OF PIPELINE CONSTRUCTION IN ARCTICAND SUBARCTIC REGIONS AND APPARATUS FORCARRYING OUT THE SAMEAbstract of the DisclosureMethods of pipeline construction in arctic andsubarctic regions and apparatus for carrying out these methodsare disclosed. Summer-constructed fabrication yards areestablished at central locations along the pipeline right-of-way spaced at intervals of 100 to 150 miles each comprisinga group of buildings utilized to fabricate instrument , andhermetically cap pipe sections, including quality control,x-ray, hydrostatic testing, external coating, final inspection,and rivet coating and weighting, along with facilities formoving pipe sections from place to place during fabrication,inspection, coating, etc. After fabrication, the pipe sectionsare stored in a marshalling yard located near the end of thefabrication yard nearest the half-division in which it willbe installed. In winter each pipe section is towed to itsplace of installation over a working snow pad or snow roadfollowing the pipeline right-of-way, for instance, by a pairof large tow tractors operating in tandem. Sensors or sensinginstruments mounted on or in the pipe section during fabricationare cabled to indicating instruments in the lead tow tractor,to assure that while in transit the pipe section undergoes nobend less than its permissible roped radius of curvature.The forward end of the pipe section being towed is mountedon a nose sled bearing a compressor and air heater for thepurpose of maintaining an elevated temperature inside thehermetically sealed pipe section. To prevent "slideouts" orthe like, portions of the pipe may be mounted on special"pipe sleds" provided with a lifting means which enable asideboom tractor to raise a portion of the pipe section orimpart a pull to assist in preventing sideslipping. Whena pipe section is being moved, a number of sideboom tractorsaccompany the pipe section, guiding respective portions ofit in special roller cradles equipped with remotely controlledpipe-gripping means or brakes.