Key Parameters Of Design And Its Application In Suspended Pipeline Control

Cezheng submarine pipeline is not only one of the important part of Ningbo-Shanghai-Nanjing crude pipeline,but aslo is the only channel of import crude oil transmission in Zhoushan city,responsible for transporting crude oil to refining company,such as Zhenhai,Shanghai,Jiangsu and the area along the Changjiang river.Due to the trend of flow rate along the pipeline route,and affected by the surrounding large-scale project construction,the detection has been carrid out in two years from 2014 to 2015,suggests 66% length of pipeline under barenessor suspending and the largest altitude of suspending up to 1.8m.In order to ensure the safe operation of pipeline and remove potential safety hazard,operators is expected to carriy out security governing.In this paper,based on inspection information and pipeline basic data from the previous year,Using the allowable stress method,calculating circumferential stress,axial stress and horizontal bending stress under the pipeline in place,and checking the equivalent stress and strain in earthquake conditions,and then applying of SAGE Profile 3D software to calculate the single largest pipe settling depth under empty and water filled condition,calculate the length of the transition section in 3.5m and 4m trenching depth,check whether the bending stress of current pipeline under the water filling condition satisfies the pipe bending stress,analyze the construction steps for the maximum suspending area.According to the key parameters and refer to the previous construction experience,developping the construction schedule and select the vessels and equipment to carry out pipeline settling operation,to clear the sandbag removement and the concrete chain in suspended segment.After finish above-mentioned work,it is necessary to invest the pipeline elevation and select typical uneven area for reviewing the bending stress and re-settling pipeline.The study result shows that,the stress of the operating conditions under the state of the pipeline conforms to the standard stress requirements.The software,SAGE Profile 3D,could effectively support in analysis ofthe key parameters of pipeline.,the date is verified in the pipeline settling construction.The submersible high-pressure ditching machine could meet the 4 meters depth in general soil,the modified high-pressure ditching machine is highly effective in crushing and removing the sandbags.Pipeline settling is a economic and effective way to solve pipeline bearness and suspending.Considering the reliability,degree and cost of control,the full-line settlement to control the pipeline bearness and suspending is more efficient and feasible than the settlement of throwing sandbag and full-line filling riprap.