Research On The Design And Material Selection Of Mechanical Bimetal Composite Pipe

Bi-metal lined pipe,which mechanically lined corrosion resistant alloy(CRA)pipe inside the carbon steel base pipe,could offer promising capacity of anti-corrosion,available strength,and lower cost for the petroleum industry.At present,the application of bi-metal lined pipe is more and more extensive in the oil-gas gathering and transferring system.Linepipe will be damaged under compression in complicated geological environments,like ovalization,wrinkling and collapse.In this paper,this paper researched the collapse strength of bi-metal lined pipe under uniform and nonuniform load,and the structural design and material selection of the bi-metal lined pipe.The main research content is as follows:(1)Based on the processing mechanism of the bi-metal lined pipe,the calculation formula of collapse strength has been established under uniform and nonuniform load.By applying the formula,this paper analyzed the main effect factors on the collapse resistance of the bi-metal lined pipe.(2)The collapse resistance of the 20G/316L was studied on basis of the equipment and method what designed in this paper.The mechanical behavior of the bi-metal lined pipe on the elastic,plastic and structural instability was researched.In addition,the collapse resistance of the 20G/316L is 3.38 MPa,which is consistent with the theoretical calculation of the collapse resistance of 3.54 MPa.(3)The mechanical properties of mechanical and metallurgical bi-metal lined pipes are tested.The composite method has little effect on the basic mechanical properties of bi-metal lined pipe,but it has a great influence on the interface bonding strength.The bonding strength of metallurgical bi-metal lined pipe is much greater than the bonding strength of mechanical bi-metal lined pipe.(4)Based on the structural design model,the structure of bi-metal lined pipe applied seabed and buried oil-gas gathering was designed.(5)The phase and microstructure of the stainless steel materials are analyzed by the calculation of phase diagrams(CALPHAD)method.Using the data from the calculated phase diagram,the stability parameters and pitting resistance equivalent of stainless steel are calculated.Thus,the materials selection method based on the phase diagram calculation method is established.