Calculation Of Internal Pressure Resistance Of Mechanical Bimetal Composite Pipe

The exploitation of oil and gas resources gradually developes into the corrosive areas with higher H2S and CO2 contents due to the expansion of energy demand.In order to solve the corrosion problem and prolong the service life of the pipeline,the utilization of bimetallic pipe already spread out into sour environment.However,the internal pressure is one of the biggest issues for pipeline engineering.The factors which affect the strength such as mechanical properties and geometrical parameters of the pipe are still ambiguous.In addition,the theoretical support of processing selection and parameters design are not sufficient.Therefore,this paper aims at creating an accurate model to calculate the anti-internal pressure strength of mechanically bonded bimetallic pipe.On the basis of the relevant literature at home and abroad,the following research works have been carried out.(1)The internal pressure strength prediction model of mechanically bonded bimetallic pipe was established firstly.Based on the stress boundary condition,the stress,strain and displacement formulas of the two layers were derived from the elastic theory.Then according to the displacement of the tube during elastic deformation,the mathematic model of bimetallic pipe's resistance to inner pressure was analyzed with the geometric parameters,performance parameters and the amount of interference.The critical value was calculated by the Mises yield criterion.And the internal pressure strength of the bimetallic pipes in different sizes was calculated using the formula.The relationship between the internal strength and the mechanical properties of the bimetallic pipe was discussed.(2)Experimental tests on the internal strength of mechanically bonded bimetallic pipe were also implemented.According to the detection of the mechanical properties,yield strength and bonding strength of pipe were successfully obtained.Besides,the deformation of bimetallic pipe under inner pressure was acquired by measuring the internal resistance of the pipe with the outer diameter of 160.00 mm and the total wall thickness of 7.00 mm(the thickness of the base pipe was 5.00 mm).(3)The ABAQUS finite element method was used to establish the two-dimensional plane strain model of bimetallic pipe.The internal pressure strength was analyzed based on the test one.And then,discussed the main factors(Grade,diameter to thickness ratio of base pipe,the modulus ratio of liner to base pipe,bond strength)affecting the internal pressure.(4)In view of the facts that the H2S,CO2 corrosion and the pressure are serious,the important production parameters of the bimetallic pipe under the uniform internal pressure were calculated according to the thesis,which provided the guidance for the numerical model on the optimization and selection of the bimetallic pipe.In this paper,the theoretical model of burst pressure strength of bimetallic pipe has been established.Then the self-designed test device has been used to study the strength and anti-internal pressure of bimetallic pipe.Thus the reliability of theoretical model has been verified by experiments and finite element simulation.The results obtained from this study will be useful data for bimetallic pipeline designers and researchers.