Calculate subsea pipeline allowable external collapse pressure, allowable buckle propagation pressure and allowable water depth (DNVGL-ST-F101 Section 5.4.4).
The internal pressure should be the minimum that can be sustained (normally zero). The external pressure should be calculated at the deepest section of the pipeline, with the highest astronomical tide (HAT), plus storm surge.
The buckle propagation check is normally only required if the pipeline fails the collapse buckling check. If the pipeline fails both the collapse pressure check and the propagation buckling check, buckle arrestors may be required.
Use the Result Table option to display a table of the allowable external pressure and allowable water depth versus wall thickness for the selected pipe diameter.
Tool Input
- pletype : Local External Pressure Type
- Pleu : User Defined Local External Pressure
- ρe : External Fluid Density
- Zs : Surface Elevation
- Zl : Local Elevation
- plitype : Local Internal Pressure Type
- Pliu : User Defined Internal Pressure At Local Elevation
- syutype : Stress Table Type
- mattype : Material Strength Type
- SMYSu : User Defined Specified Minimum Yield Stress
- syttype : Temperature Derating Type
- Td : Operating Temperature
- fytu : User Defined Yield Stress Temperature Derating
- autype : Material Strength Factor Type
- schdtype : Pipe Schedule Type
- diamtype : Pipe Diameter Type
- ODu : User Defined Outside Diameter
- IDu : User Defined Inside Diameter
- wtntype : Wall Thickness Type
- tnu : User Defined Wall Thickness
- ttoltype : Wall Thickness Tolerance Type
- xfu : User Defined Negative Wall Thickness Fraction
- tfu : User Defined Negative Wall Thickness Allowance
- modptype : Pipe Material Type
- νu : User Defined Pipe Poisson's Ratio
- Eu : User Defined Pipe Elastic Modulus
- gsctype : Safety Class Resistance Factor Type
- γscu : User Defined Load Controlled Resistance Factor
- optype : Characteristic Wall Thickness Type
- fabtype : Fabrication Factor Type
- αfabu : User Defined Fabrication Factor
- ta : Corrosion Allowance
- fo : Pipe Ovality
Tool Output
- ΔPl : Delta Pressure Across Pipe Wall At Local Elevation
- αfab : Fabrication Factor
- αu : Material Strength Factor
- γm : Material Resistance Factor
- γsc : Safety Class Resistance Factor
- ν : Pipe Poisson's Ratio
- E : Pipe Elastic Modulus
- OD : Pipe Nominal Outside Diameter
- OD/tn : Diameter Over Wall Thickness Ratio
- Pc : External Collapse Pressure
- Pca : Allowable External Pressure Colllapse Buckling
- Pel : Elastic Collapse Pressure
- Ple : External Pressure At Local Elevation
- Ple/Pca : Local External Pressure Over Allowable Collapse Pressure Ratio (≤ 1)
- Ple/Ppa : Local External Pressure Over Allowable Propagating Pressure Ratio (≤ 1)
- Pli : Internal Pressure At Local Elevation
- Pp : Propagating Buckle Pressure
- Ppa : Allowable Propagating Buckle Pressure
- Py : Plastic Collapse Pressure
- SMYS : Specified Minimum Yield Stress
- fy : Yield Stress
- fyt : Yield Derating Stress
- t1 : Wall Thickness t1
- t2 : Wall Thickness t2
- tf : Fabrication Thickness
- tn : Pipe Nominal Wall Thickness
- wd : Water Depth At Local Elevation
- wdca : Allowable Water Depth External Collapse
- wdpa : Allowable Water Depth Propagation Buckling