| In recent years,oil and gas fields are facing corrosion problems such as high H2S,CO2,O2,residual acid and other highly mineralized and acidic oil,gas and water media,which bring great risks to the application of steel pipes such as carbon steel and low alloy steel.Adhesive glass fiber thermoplastic composite pipe,as a typical nonmetallic composite pipe,has a series of advantages such as corrosion resistance,easy bending,light weight,convenient transportation and construction,etc.It has become one of the important solutions for anticorrosion of oil field surface gathering and transportation pipe network,and is the main development direction of oil field pipe.As the terminal connection device of the pipeline system,the structure and sealing performance of the joint play a decisive role in the pressure bearing performance of the composite pipe.At present,most scholars at home and abroad focus on the research of composite pipes and their joints for offshore oil and gas transportation,while onshore oil exploitation accounts for a large proportion in China's oil exploitation and offshore oil exploitation is relatively small.Therefore,it is of certain engineering practical significance to carry out the research on pipelines and their joints for onshore oil and gas fields.The structure of adhesive glass fiber thermoplastic composite pipe and its joints for land oil and gas transportation are designed in this paper.The specific research contents include:(1)By analyzing the characteristics of common lining materials,polyvinylidene fluoride(PVDF)and high density polyethylene(HDPE)are finally selected as lining materials according to the service conditions of pipelines.The mechanical property parameters of PVDF and HDPE were obtained through relevant experiments,in which the yield strength of PVDF was 50MPa,the elastic modulus was 2000 MPa,the yield strength of HDPE was 20MPa,and the elastic modulus was 600 MPa;.(2)According to the manufacturing process and analysis of adhesive glass fiber thermoplastic composite pipe,it is found that the main factors affecting the thickness of lining layer are the winding mode of glass fiber tape,the number of winding layers and the heating temperature.Through finite element analysis,it is found that the minimum thickness of the inner lining of the adhesive glass fiber thermoplastic composite pipe with a diameter of?65mm is 3.7 mm at normal temperature and 4 mm at heating temperature.(3)According to the technical design indexes of the buried adhesive glass fiber thermoplastic composite pipe and referring to relevant specifications,the reinforced layer structure of the composite pipe under design load is designed.The designed pipeline can meet the strength design requirements.Through checking,it is finally concluded that for the composite pipe with a diameter of?65 mm,a design pressure of 15 MPa and a winding angle of ±55°,the minimum number of winding layers for the reinforced layer is 8.(4)The maximum tensile load and the minimum bending radius of the designed bonded glass fiber reinforced composite pipe are checked by finite element analysis software.After checking,the maximum axial tensile load that adhesive glass fiber thermoplastic composite pipe with diameter of ?65 mm,winding angle of ± 55°,and winding layer number of 8 can bear is 80 KN,and the minimum bending radius under no internal pressure and internal pressure are 1.78 m and 2.8 m respectively.(5)Determine the special joint structure and seal type of adhesive glass fiber thermoplastic composite pipe,mainly with O-type seal as the main and extrusion seal as the auxiliary.Through Abaqus finite element analysis software,the strength and sealing performance of the designed joint structure are checked.After checking,the joint structure can meet the design load and sealing requirements. |
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