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| Home | Contact Us | Tue, January 6, 2009 |
Mechanics Of Tubular Products Area
Area Head
Ing. Rita G. ToscanoObjectives
- The optimization of existing threaded connections and the development of new proprietary threaded connections for OCTG and sucker rods.
- The enhancement of the collapse resistance of tubular products (casing and deep water line pipes).
- The development of finite element models to study the performance of threaded connections, of deep water line pipes, of pipe-in-pipe systems, etc.
- The coordination of all the technical efforts developed at CINI in the field of threaded connections and mechanical behavior of tubular products.
Research areas
Analysis of OCTG (oil country tubular goods) threaded connections
Increase of the knowledge on special connections. Optimization of connection designs. Development of new connections.Jump out
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In an API 8-Round connection, the levels of equivalent plastic strain for different tensile loads and the development of the jump-out phenomenon are shown. |
Finite element analysis of the API-8R threaded connection displaying the jump-out.
Localized plastic deformation. A finite element simulation of the necking of a casing premium connection is presented. The failure is localized out of the threaded area. The load-displacement path is also indicated, for two different thread shapes that have an identical performance.
 The failure was localized far away from the threaded area (Necking) |
 No localization (no necking) |
| Equivalent plastic strains | |
 Perfect plastic material |
 Material with hardening |
| Load- displacement curves | |
Shear bands in the connection couplings
 External pressure |
 Overtorque |
 Compression |
Equivalent plastic strains for ultimate loads
 Equivalent plastic strains |
 Resulting contact force on seal |
 Resulting contact force on shoulder |
| The behavior of two connections was compared, in order to evaluate the effect of the load flank angle. | |
 Contact stress distribution. Cone-to-cone and sphere-to-cone metal-to-metal seals |
 Thermal loads |
 Mechanical loads |
 Finite element results. Equivalent plastic strains |
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| Seal contact pressure | |
From the equivalent plastic strain and contact pressure plots it is evident that successive cycles do not produce plastic ratcheting in the connection.
Sucker rods threaded connection
Development of a sucker rod connection, with enhanced fatigue resistance.
 API design |
 New design |
| Finite element meshes | |
 API design |
 New design |
| Comparison between the API design and the New Design for 7/8” Grade D | |
Analysis of the collapse behavior of steel pipes including the post-collapse regime
(e.g. collapse propagation in deep water line pipes)
The objective is to increase the knowledge of the effect of different imperfections on the collapse resistance of tubular products.
 External pressure vs. ovality for a pipe with an applied curvature |
 Initial, intermediate and final shapes of the pipe cross section. Equivalent plastic strains |
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Collapse and post-collapse behavior of a Deep Water Line Pipe |
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| Ovality effect on the collapse pressure and on the propagation collapse pressure of a curved pipe | |
 Fourier decomposition of the pipe external surface using the “shapemeter” |
 Thickness distribution |
 Pre and post-collapse equilibrium path. Experimental (blue) vs. numerical results (black) |
 Finite element meshes corresponding to four stages along the equilibrium path |
 Contact forces on the deformed pipe configuration during collapse propagation |
 Equivalent logarithmic strains |
Terms and Conditions