Steel Reinforced Ducts Stressed by Temperature

Steel pipelines are an important part of industrial operations in many sectors. Pipelines serve to transport media in liquid and gaseous state. Ducts, with a ratio of pipe diameter to wall thickness up to 150 are considered as simple beams. Ducts with higher ratio are considered as shell elements. In literature we can find how to calculate these structures stressed by many kinds of load. Failures, that have occurred in recent past suggest, that the issue of industrial piping design is not yet fully explored.The phenomenon presented in this study is behaviour of reinforced steel shell stressed by temperature changes. Due to high temperature load, there is a big temperature deformation of the whole system. However, the deformation caused by temperature is not the same in all parts of the system. As the high temperature source is inside the pipe, the highest temperature is on the inner surface of the shell. The variation of the temperature in the shell and partial warming of ring stiffeners is caused by heat conduction. Due to the different temperatures of the surrounding environment, the stiffener is warmed less than the shell. Therefore the shell and the stiffener are deformed in a different way.The research is, in more details, focused on the area close to the ring stiffener, where it is a higher possibility of cracks initiation and their expansion due to the cyclical stress. The aim of this study is a construction life diagnosis considering this detail; eventually a proposal of a more effective construction detail.