Elastic interaction of couplings and pipes walls in tight threaded joints

Box threaded connections of pipes are used at oil and gas recovery. The pipe and the coupling interact elastically by their tapered surfaces with radial tightness in the thread and the sealing. Strength and impermeability of the connection depends on this interaction.The pipe and the coupling are thin-walled cylinders with the linear variable wall thickness. Their sections have varying lengthwise rigidity of walls and axial-symmetric bends. Therefore, their calculation differs from the Lame problem and from the calculation of cylinders with the fixed wall thickness.Physical and mathematical principles of the calculating parameters of elastic-strained state of all parts of pipe walls and coupling connections with the sealing box have been formulated in the article.