<p>LNG(Liquefied Natural Gas) cryogenic hoses can be used for the transmission of liquefied natural gas. It is a key component equipment of LNG production and transmission system. As the inner lining of LNG cryogenic hoses, metal bellows directly contact with the cryogenic transmission media. The safety performance of the bellow is quite important and the failure of instability endangers the safety of bellows seriously. Torsional buckling instability is one of the main failure modes of the metal bellow, while the research on the instability of bellows under torsional loads is still insufficient at present. In this paper, the theoretical model and finite element model of a U-shaped bellow are established. The effects of cross-section geometric parameters (convolution height, convolution pitch, wall thickness, etc.) on the stiffness of the U-shaped bellow are compared and analyzed, and the corresponding sensitivity results are summarized. The linear buckling analysis and the post-buckling analysis of U-shaped bellows under torsional loads are carried out. By comparing the analysis results obtained by the finite element model established in this paper and the theoretical model results with the experiments in the reference, it is shown that results from the finite element analysis in this paper have the same buckling mode as the experimental results in the reference. And the finite element analysis results have a relatively higher precision than that of the theoretical model. On this basis, the effects of manufacturing defects of bellow, such as thickness thinning, eccentricity and material plasticity, on the torsional stability of bellows are studied. It is found that these defects can significantly reduce the stability of bellows. Especially the spiral characteristics of the bellows may have effects on the loading bearing and fail after entering the elastic-plastic post-buckling stage. These characteristics need to be paid enough attention in the structure design of LNG cryogenic hoses.</p>

Torsional Buckling Analysis of Lined Bellows in Lng Cryogenic Hoses

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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