A new steel expansion joint for industrial plants: Bubble joint

In power, steel, chemical and other industrial plants, ducts are essential to carry air and effluent gases. Ducts are designed such that under the temperature they can expand and contract freely in order to eliminate internal thermal stresses. To allow for free movements, expansion joints are introduced at the points of change in direction and also in long duct runs. Whenever large lateral movements are encountered, either a very deep single expansion joint or a toggle section with two joints is currently used in practice. In this article, a new type of steel expansion joint is proposed by introducing a bubble in the center of the single expansion joint with the goal of increasing its lateral movement capacity. The lateral movement capacity of the proposed joint is investigated by finite element simulation taking into account both material and geometrical nonlinearities. The results show that the new steel bubble joint can accommodate substantially more lateral movements than the conventional steel expansion joint. The new bubble joint provides an economical solution for retrofitting an existing plant where the available space is limited.