Integrated Mechanical Strength Tests of the Main Pipeline for Transporting Crude Oil and Refined Products

The state, problems, and prospects of conventional, unified and special laboratory, bench and full-scale tests to substantiate the systematic assessment of strength, durability, survivability, cold resistance, reliability, and safety of the key elements of pipeline transport of crude oil and refined products are considered. These tests correlate with the stages of the pipeline life cycles and basic and reference computational-experimental methods of determining the criterial characteristics of pipe steels, pipes and main pipelines with regard to domestic and foreign practices. The experimental basic mechanical characteristics obtained in standard static tensile tests (yield and strength limits, elastic moduli) are part of the basic static strength calculations of newly designed and operating pipelines. Standard hardness and impact elasticity tests are used to control the pipe steel quality. The results of standard tensile tests provide additional design information for the assessment of static strength with respect to the ductility and degree of steel hardening during elastoplastic deformation. Unified laboratory tests are meant for refining the pipeline strength with allowance for the stress state 3D effects, absolute sizes of the pipeline cross section, strain rate, anisotropy, cold resistance, corrosion, and the presence of welded joints. The assessment of pipe steel crack resistance and pipes according to the criteria of linear and nonlinear fracture mechanics with allowance for technological and operational defects holds a specific place in laboratory and bench testing. The experience in conducting these tests, accumulated in the Russian oil pipeline system is considered.