Determination of Failure Pressure Modes of the API Specification 12F Shop-Welded, Flat-Bottom Tanks

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Andres Rondon ◽  
Sukru Guzey
Keyword(s):  
Stress Analysis ◽  
Buckling Analysis ◽  
Flat Bottom ◽  
Welded Steel ◽  
Failure Pressure ◽  
Steel Material ◽  
Current Design ◽  
Steel Tanks ◽  
Post Buckling ◽  
Internal Pressures

Shop–welded, flat-bottom tanks for storage of production liquids are designed and fabricated in specific dimensions and capacities for internal pressures close to atmospheric pressure in accordance with the API 12F specification. This study addresses the failure pressure on the eleven (11) current API 12F shop-welded steel tanks as well as two proposed sizes through finite element and stress analysis of more than 350 different tank models. An elastic analysis was carried out to determine the yielding pressure of the shell-to-bottom and roof-to-shell joints. An elastic buckling analysis and a post-buckling analysis including imperfections was performed to determine the buckling modes of the equipment. The redistribution of stresses due to inelastic deformations and plastic collapse were evaluated through a plastic stress analysis considering the stress–strain hardening of the ASTM A36 mild steel material. Moreover, the design pressure increase to failure pressure or 24 oz/in2 (10.3 kPa) was investigated regarding the stress levels and bottom uplift of the 13 flat-bottom tanks. The presented research provides meaningful insights and engineering calculations to evaluate the current design of the API 12F shop-welded, flat-bottom tanks as well as to establish new design internal pressures guaranteeing a safe performance of the equipment.

Evaluation of the Design Pressure and Failure Modes for the API 12F Shop Welded Flat Bottom Tanks for Oil Storage

2016 ◽  
Author(s):  
Andres Rondon ◽  
Sukru Guzey
Keyword(s):  
Stress Analysis ◽  
Failure Modes ◽  
Mode Analysis ◽  
Separate Analysis ◽  
Flat Bottom ◽  
Buckling Mode ◽  
Oil Storage ◽  
Current Design ◽  
Safe Performance ◽  
Design Pressure

This study aims to determine the failure modes of the eleven API 12F shop welded tanks plus two proposed new sizes through finite element and stress analysis of more than 350 different models. Four separate analysis where carried out throughout this investigation. An elastic stress analysis considering non-linear deformations was performed to determine the yielding pressure of the tanks and maximum design pressure. An elastic buckling mode analysis evaluated the potential buckling pressure as a failure mode of the tanks. The redistribution of stresses due to inelastic deformations and plastic collapse were evaluated through an elastic-plastic stress analysis. Finally, a wind load analysis was developed to study the stress levels and uplift deformation of the API 12F tank with greatest aspect ratio (H/D). The presented research provides meaningful engineering calculations to evaluate the current design and capacity of the API 12F flat bottom tanks guaranteeing a safe performance of the equipments.

Thermal Post-Buckling Analysis of Functionally Graded Composite Plates with Nonlinear Aerodynamic Forces

2010 ◽  
Vol 123-125 ◽  
pp. 280-283
Author(s):  
Chang Yull Lee ◽  
Ji Hwan Kim
Keyword(s):  
Material Properties ◽  
Numerical Solutions ◽  
Virtual Work ◽  
Shear Deformation Theory ◽  
Composite Plates ◽  
Buckling Analysis ◽  
Functionally Graded ◽  
Governing Equations ◽  
Functionally Graded Composite ◽  
Post Buckling

The post-buckling of the functionally graded composite plate under thermal environment with aerodynamic loading is studied. The structural model has three layers with ceramic, FGM and metal, respectively. The outer layers of the sandwich plate are different homogeneous and isotropic material properties for ceramic and metal. Whereas the core is FGM layer, material properties vary continuously from one interface to the other in the thickness direction according to a simple power law distribution in terms of the volume fractions. Governing equations are derived by using the principle of virtual work and numerical solutions are solved through a finite element method. The first-order shear deformation theory and von-Karman strain-displacement relations are based to derive governing equations of the plate. Aerodynamic effects are dealt by adopting nonlinear third-order piston theory for structural and aerodynamic nonlinearity. The Newton-Raphson iterative method applied for solving the nonlinear equations of the thermal post-buckling analysis

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