Test and Study of Elbow Stress of Directly Buried Heat-supply Pipeline

摘要

Directly buried installation without expansion joint is chosen more and more in municipal heat-supply system of heat and power cogeneration. But neglectfulness in design and construction can shorten the life of elbows, tees and valves etc. whose stresses are centralized, even result in pipe crack especially for large bore pipe. The paper introduces stress test project and method of directly buried pipeline's elbows, whose diameter are DN600, points out that the stress in the middle parts of elbows is bigger than that in the roots of elbows, brings forward calculation method about length and displacement of partly restrained section with a elbow, the results of experiments indicate that elbow stress relate to pipeline's burying depth and its curvature radius, the paper also puts forward restrictive conditions about burying depth, curvature radius, dimension coefficient and so on.