Laying key points of oil and gas pipelines in common tunnel

The technology of two pipes laying in common tunnel is used in several pipelines of the third section of LanCheng-ZhongGui Oil and Gas Pipeline Project which are under construction in China. To ensure the safety of pipeline laying and shorten the laying period, this paper discusses the existing problems in the oil and gas pipelines laying in common tunnel and solutions, lists the technical difficulties of main procedure and puts forward the construction suggestions. The pipe laying solutions are as follows: (1) the pathway and portal frame are used to convey and lay pipe; (2) two pipes are synchronously welded; (3) reasonably planning the welding and backfilling steps of the pipelines in a steep slope tunnel are important; (4) the coordination to every working process based on an continuous way should be made and (5) the safety of operators must be guaranteed, etc.. The main working procedures include pipe conveyance and laying in tunnel, welding, inspection and repair, pipelines in position and backfilling, pipeline hydrotest and tunnel enclosure.