Structural FEA of LPG Bullet Tanks

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  Propane finite element model

  The full model represents the shell courses, ends, top connections and attachment regions as one structural assembly

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  Butane RevD finite element model

  The meshed assembly retains the detailed reinforcement and stiffener arrangement used in the pressure assessment

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  Through-thickness layers

  The Butane RevD report specifies three element layers through the shell and head thickness for stress linearization

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  Dome and nozzle interfaces

  Local mesh detail represents the changes in shape where openings interrupt the cylindrical shell

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  Internal ring stiffeners

  Separate ring views make it possible to follow the stress distribution in these internal members

Propane images use the consolidated Rev00 report for the RevD model. Butane R2 denotes earlier studies; these are not presented as a complete revalidation of the later RevD geometry

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  Propane: 1.85 MPa

  The case-specific loading definition applies internal pressure to the vessel, alongside the defined external pressure and operating loads

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  Butane: 0.883 MPa

  The RevD model has its own design-pressure basis. The two tanks are assessed against their respective loading definitions

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  Contents and gravity

  The operating setup represents hydrostatic head over 85% of the tank diameter, together with self-weight

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  Propane: 293.83 MPa

  The original equivalent-stress plot shows the highest local value near the end connections. The shell, rings and openings are then examined separately

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  Butane RevD finite element model

  The original pressure-case contour identifies the higher-demand region in the revised vessel assembly. Detailed stress-category checks follow

These are local equivalent-stress maxima, not membrane-stress acceptance values. The tanks have different pressure bases, so this comparison does not rank their performance

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  Propane dish-end path

  The SCL crosses the wall at a selected high-stress location. The thickness-average membrane response and linear bending component support the stress-category assessment

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  Butane RevD dish-end path

  The revised geometry has corresponding SCL checks. Membrane and membrane-plus-bending results are compared with the limits for the assigned stress category and loading condition

Selected equivalent-stress values from the detailed tables; membrane + bending uses the larger reported surface value. The reports record satisfaction of the applicable checks for these paths. Their stated general membrane limit is 137.9 MPa; the corresponding combined limit is 206.85 MPa.

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  Reinforcement pads

  Recorded pad diameters: dome 2,950 mm, manhole 2,300 mm and N2 nozzle 1,280 mm. A 1:3 chamfer provides the specified transition

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  Dome wall thickness

  The documented dome arrangement uses a 38 mm lower ring and a 20 mm upper ring

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  Shell-to-head stiffeners

  The revision adds the detailed stiffener arrangement at the shell-to-dish-end junction, including 20 mm-thick plates

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  Propane: longitudinal stress

  The longitudinal seismic case reports a local equivalent-stress maximum of about 299.4 MPa in the consolidated study

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  Butane R2: longitudinal stress

  The earlier butane model shows a 369.26 MPa local maximum. This result belongs to the R2 study and is not a RevD acceptance result

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  Butane R2: longitudinal movement

  The original plot shows 10.265 mm maximum total deformation, with movement distributed along the shell and between the internal rings

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  Butane R2: lateral stress

  The lateral contour shows 255.84 MPa maximum equivalent stress. The change in direction alters both the stress distribution and the locations carrying higher demand

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  Propane hydrotest study

  The original equivalent-stress contour reaches 485.35 MPa locally. The report also examines selected stress-linearization paths under its test-condition criteria

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  Butane R2 hydrotest study

  The earlier butane contour reaches 401.45 MPa locally. The separate study traces the demand through the shell, ends, stiffeners and openings

These plots are analysis outputs, not physical hydrotest records. Local peaks exceed the stated material yield strength and require the report’s stress-category and modelling context; they do not establish an unrestricted pass

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  Two support assumptions

  The archived diagrams vary support along the vessel length to represent alternative subgrade distributions

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  Applying the support to the FE model

  The model assigns different support values along the lower shell. This tests the sensitivity of the vessel to the assumed bedding response

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  Butane R2: first arrangement

  The first displayed support arrangement gives about 23.08 mm maximum total deformation. The local movement follows the changed support distribution

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  Butane R2: second arrangement

  The second arrangement gives about 19.4 mm maximum total deformation. Both the displacement pattern and component stresses were reviewed

The propane study also includes two support-imbalance conditions. These are prescribed support scenarios; they are not site settlement measurements or a geotechnical verification

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  End section with dome

  The original propane model includes the dish end, a length of shell, internal rings and top connections

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  Cylindrical shell section

  The shell-only model has its own attachment positions and local response. These are partial-section studies

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  Propane end-section movement

  The source plot reports about 1.5 mm maximum total deformation for the modelled lifting condition

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  Butane R2 end-section movement

  The original contour reports 3.18 mm maximum total deformation. The open shell edge and attachment regions show distinct movement

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  Propane lifting lug

  The isolated attachment plot shows approximately 200 MPa local equivalent stress for the end-section lifting case

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  Butane R2 lifting lug

  The earlier butane attachment result shows 301.29 MPa locally. The report also reviews the adjoining shell and internal rings

These results apply to the modelled sections, self-weight and restraint assumptions. They do not describe a complete-vessel lift or an approved site rigging procedure