Study On Strength Behavior Of Hot Tapping Pipe

Hot tapping developed from the 1960's is an advanced technology of piping rebuilding and first-aiding. It can solve the problem meeting in the continuous production and can take good economical and social effects, so it is widely used in many fields. At the present time, the main research about hot tapping is the use of the technology, the study about strength behavior of hot tapping pipe is little. To get the stress distribution and the limit load of hot tapping pipe, it is necessary to analyze the strength behavior of hot tapping pipe.Supported by China Petroleum & Chemical Corporation, strength behavior of hot tapping pipe under internal pressure and moment was studied by experiment and FEA, the main work in this thesis are as following:(1) Tests were performed to study the elastic stress distribution and limit loads of hot tapping models under internal pressure and moment. Twice-elastic-slope rule was used to gain the limit loads of models from load-strain and load-displacement curves.(2) Contact behavior of model under internal pressure was investigated to study the deformation and contact pressure between main pipe-branch and main pipe-reinforcement pad. Limit analysis of the model with contact was also performed.(3) Besides the models used in the experiment, six analysis models were studied by three-dimension nonlinear finite element method and a series of data and conclusions were obtained.(4) To gain the conclusion of the study, analysis and comparison about contact, elastic stress and limit loads which got from experiment and FEA was carried out.(5) A series of parametric models with different d/D, t/T and D/T were made to gain the empirical formula about limit loads of hot tapping models.Some conclusions were obtained through the study above:(1) The local stress concentration of models under internal pressure and moment is obvious. The stress rapidly attenuates to the normal stress level with the increase of the distance from the opening.