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Pipeline Buckling Modules

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CALCULATOR MODULE : Beam Buckling Load   ±

Calculate beam buckling load for general beams (user defined stiffness EI).

Beam end types include: free fixed (cantilever), guided fixed, pinned fixed, fixed fixed (built in or fixed), pinned pinned (simply supported), and guided pinned beam ends. The beam end conditions are of the form left end - right end (for example Pin-Fix is left end pinned and right end fixed).

The buckling load can be calculated using either the Euler equation (suitable for long beams), the Johnson equation (suitable for short beams), or the buckling load equation can be determined from the transition length. The buckling load is positive. The axial load is negative in compression. Buckling will generally occur about the axis with the lowest EI, depending on constraints.

The effective length factor should be used for beams on a soft foundation such as soil, where the beam ends are poorly defined. For defined beam ends, such as structures, the effective length factor should be set to one (fe = 1).

Use the Result Plot option to plot the buckling load versus nominal length. Use the Result Table option to plot the buckling load versus end type. Refer to the figures and help pages for more details. Refer to the links below for other beam options.

Reference : Roark's Formulas For Stress And Strain, Warren C Young, McGraw Hill

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CALCULATOR MODULE : Pipe Beam Buckling Load   ±

Calculate beam buckling load for pipe beams.

Beam end types include: free fixed (cantilever), guided fixed, pinned fixed, fixed fixed (built in or fixed), pinned pinned (simply supported), and guided pinned beam ends. The beam end conditions are of the form left end - right end (for example Pin-Fix is left end pinned and right end fixed).

The buckling load can be calculated using either the Euler equation (suitable for long beams), the Johnson equation (suitable for short beams), or the buckling load equation can be determined from the transition length. The buckling load is positive. The axial load is negative in compression. Buckling will generally occur about the axis with the lowest EI, depending on constraints.

The effective length factor should be used for beams on a soft foundation such as soil, where the beam ends are poorly defined. For defined beam ends, such as structures, the effective length factor should be set to one (fe = 1).

Concrete stiffness can be included in EI by multiplying EI by a factor (1 + CSF). The concrete stiffness factor is calculated from the ratio of concrete EI over beam EI in accordance with DNVGL RP F105. The method is suitable for circular beams and pipes. For other profile shapes engineering judgement is required.

Use the Result Plot option to plot the buckling load versus nominal length. Use the Result Table option to plot the buckling load versus end type. Refer to the figures and help pages for more details.

Reference : Roark's Formulas For Stress And Strain, Warren C Young, McGraw Hill

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CALCULATOR MODULE : Pipeline Collapse Pressure   ±
CALCULATOR MODULE : DNVGL ST F101 Submarine Pipeline Collapse Pressure   ±

Calculate DNVGL-ST-F101 submarine pipeline external collapse pressure and propagating buckle pressure.

The external pressure should be calculated for the maximum water depth. Propagating buckles are only a problem if collapse has occurred. Buckle arrestors may be required to minimse the risk of propagating buckling.

Reference : DNVGL-ST-F101 : Submarine Pipeline Systems (Download from the DNVGL website)

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CALCULATOR MODULE : DNVGL ST F101 Submarine Pipeline Local Buckling   ±

Calculate DNVGL-ST-F101 submarine pipeline local buckling checks for combined loading.

The load controlled calculators should only be used for elastic deformation (check that the equivalent stress is less than the yield stress).

The displacement controlled calculators can be used for compressive elastic and plastic deformation. Elastic strains are calculated using the elastic modulus, and should not be used in the plastic range. Plastic strains should be calculated using finite element analysis (FEA). Use the allowable stress design (ASD) calculators for displacement controlled loads which include torsion.

Reference : DNVGL-ST-F101 : Submarine Pipeline Systems (Download from the DNVGL website)

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CALCULATOR MODULE : DNVGL ST F101 Submarine Pipeline Bend Allowable Stress Design (ASD)   ±

Calculate DNVGL-ST-F101 submarine pipeline allowable stress design (ASAD) check for combined loading. The allowable stress design (ASD) check can be used for pipeline induction bends with combined loading which includes a torsion load. The allowable stress design (ASD) check is a von Mises equivalent stress check.

Reference : DNVGL-ST-F101 : Submarine Pipeline Systems (Download from the DNVGL website)

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CALCULATOR MODULE : DNVGL ST F101 Submarine Pipeline Axial Load   ±

Calculate DNVGL-ST-F101 submarine pipeline axial load from temperature and pressure. The axial load calculations are valid in the elastic range only (check that the equivalent stress is less than the yield stress). The calculators include a combined load controlled check, displacement controlled check, allowable stress design check (ASD), and an equivalent stress check (von Mises).

Reference : DNVGL-ST-F101 : Submarine Pipeline Systems (Download from the DNVGL website)

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CALCULATOR MODULE : DNVGL ST F101 Submarine Pipeline Expansion Spool   ±

Calculate DNVGL-ST-F101 submarine expansion spool local buckling and fatigue check.

The expansion spool is modelled as a simple beam with fixed ends, with a uniform distributed load due to friction and a lateral displacement at one end due to expansion. Pipe cross section properties are calculated for a single pipe layer with no coatings. For pipes with internal liner or external coatings use the user defined cross section properties option.

Reference : DNVGL-ST-F101 : Submarine Pipeline Systems (Download from the DNVGL website)

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CALCULATOR MODULE : Hot Pipeline Hobbs Lateral And Upheaval Buckling   ±
CALCULATOR MODULE : Hot Pipeline Upheaval Buckling   ±

Calculate high temperature pipeline upheaval buckling using either the Hobbs method, the Pipeng method, or the LRSTAR method.

The Hobbs method can be used for used for pipelines lying on the seabed. The LRSTAR and Pipeng methods are suitable for buried pipelines, and have been developed using the results from finite element analysis (FEA). The LRSTAR method uses a cubic spline fit for the dimensionless Richards length number and Richards weight number. The Pipeng method uses a simple mathematical relationship between the Calladine Length number and the Calladine load number based on beam theory.

The Hobbs method calculates the initiation temperature from the global axial load, the load outside the slip zone, and hence accounts for the expansion of the pipe prior to buckling. The Pipeng method and LRSTAR method calculate the initiation temperature from the axial load in the buckle, and do not account for the expansion of the pipe prior to buckling. The Pipeng method and LRSTAR method are therefore slightly conservative. In addition, the LRSTAR method includes a built in design factor. The LRSTAR method is therefore more conservative than the Pipeng method.

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CALCULATOR MODULE : Hot Pipeline Lateral Buckling   ±
CALCULATOR MODULE : Hot Pipeline Upheaval Buckling Trigger   ±

Calculate high temperature pipeline upheaval buckling trigger height using Hobbs method.

Upheaval buckling triggers are used to initiate controlled buckling of high temperature high pressure pipelines. The trigger height should be designed so that the upheaval buckling initiation temperature is lower than the lateral buckling initiation temperature for all four lateral buckling modes. The triggers should be spaced according to the buckle initiation slip length. Use the Result Plot option to display the buckle initiation temperature versus either lateral out of straightness or trigger height, and use the goal seek option to calculate the required trigger height.

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CALCULATOR MODULE : Hot Pipeline Prop   ±
CALCULATOR MODULE : Hot Pipeline Euler Buckling Or Bar Buckling   ±

Calculate high temperature pipeline Euler buckling or bar buckling load.

Pipe end types include: free fixed (cantilever), guided fixed, pinned fixed, fixed fixed (built in or fixed), pinned pinned (simply supported), and guided pinned pipe ends. The pipe end conditions are of the form left end - right end (for example Pin-Fix is left end pinned and right end fixed).

The buckling load can be calculated using either the Euler equation (suitable for long beams), the Johnson equation (suitable for short beams), or the buckling load equation can be determined from the transition length. The buckling load is positive. The axial load is negative in compression. Buckling will generally occur about the axis with the lowest EI, depending on constraints.

The effective length factor should be used for beams on a soft foundation such as soil, where the pipe ends are poorly defined. For defined pipe ends, such as structures, the effective length factor should be set to one (fe = 1).

Concrete stiffness can be included in EI by multiplying EI by a factor (1 + CSF). The concrete stiffness factor is calculated from the ratio of concrete EI over pipe EI in accordance with DNVGL RP F105.

Use the Result Plot option to plot the buckling load versus nominal length. Use the Result Table option to display the buckling load versus end type. Refer to the figures and help pages for more details.

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Related Modules :

CALCULATOR MODULE : API RP 1111 Pipeline Axial Load   ±
CALCULATOR MODULE : API RP 1111 Pipeline Collapse Pressure   ±
CALCULATOR MODULE : API RP 1111 Pipeline Combined Loading   ±

Calculate API RP 1111 limit state pipeline combined loading check.

For the external pressure check, the external pressure should be calcuated for the maximum water depth (highest astronomical tide plus storm surge). The internal pressure should be the maximum sustainable pressure (normally zero).

For the axial load check, the axial load can be calculated for either fully constrained pipeline, unconstrained pipeline, or user defined loads.

Reference : API RP 1111 : Design, Construction, Operation, and Maintenance of Offshore Hydrocarbon Pipelines (Limit State Design) (2011)

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CALCULATOR MODULE : AS 2885.1 Pipeline Cold Bend Buckle   ±
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