Pipeline Expansion Spool

Calculate bending moment and reaction force for a pipeline expansion spool using simple beam theory. Bending is assumed to be in plane, and torsion is assumed to be equal to zero.

For expansion spools in contact with the ground, the bending moment and axial load should be calculated for combined lateral displacement and lateral friction loads. For suspended spools not in contact with the ground, the bending moment and axial load should be calculated for lateral displacement only. Bending is assumed to be in-plane. Suspended spools should be supported to prevent bi-planar or two dimensional bending.

The combined stress may be calculated using either Tresca's or Von Mises' formula. Generally, the combined stress should be less than or equal to 90% of yield. The spool stress check can be calculated for either the nominal wall thickness, or the corroded wall thickness (nominal wall thickness minus corrosion allowance).

Tool Input

• pletype : External Pressure Type
  • Peu : User Defined External Pressure
• syutype : Stress Table Type
• mattype : Yield Stress Type
  • SMYSu : User Defined Specified Minimum Yield Stress
• 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
• corrtype : Pipe Wall Corrosion Type
• modptype : Pipe Material Type
  • Eu : User Defined Pipe Elastic Modulus
  • ρpu : User Defined Pipe Density
• sectype : Pipe Section Properties Type
  • Asu : User Defined Steel Cross Section Area
  • EIu : User Defined Pipe EI Modulus
  • Zu : User Defined Pipe Z Modulus
• ifactype : Stress Factor Type
  • iiu : User Defined In Plane Stress factor
• wltype : Pipe Weight Type
  • Wlu : User Defined Pipe Unit Weight
• frictype : Pipe Soil Friction Type
  • μu : User Defined Lateral Friction Factor
  • fu : User Defined Lateral Friction Unit Force
• bendtype : Bend Location Type For Stress Check
• walltype : Hoop Stress Wall Thickness Type
  • Yuu : User Defined ASME Y Factor
• checktype : Stress Check Type
• momtype : Bending Moment Type
• tc : Corrosion Allowance
• Fd : Stress Design Factor
• Δ : End Expansion
• Lo : Spool Offset Length
• ρi : Internal Fluid Density
• ρe : External Fluid Density
• Pi : Internal Pressure

Tool Output

• ρp : Pipe Density
• As : Pipe Steel Cross Section Area
• E : Pipe Elastic Modulus
• EI : Pipe E x I
• F : Pipe Unit Friction Force
• Fg : Global Or External Axial Load
• Fs : Pipe Shear Load
• Fw : Pipe Wall Axial Load
• ID : Pipe Inside Diameter
• Lmax : Maximum Spool Length For Lateral Friction Mobilisation
• M : Bending Moment
• OD : Pipe Outside Diameter
• OD/t : Pipe Diameter Over Wall Thickness Ratio
• PΔ : Pressure Difference
• Pe : External Pressure
• SMYS : Specified Minimum Yield Stress
• Sa : Allowable Stress
• Sb : Bending Stress
• Schk : Check Stress
• Schk/Sd : Check Stress Over Allowable Stress Ratio
• Sh : Hoop Stress
• Ss : Shear Stress
• Sx : Pipe Wall Axial Stress
• W : Pipe Unit Weight
• Z : Z Section Modulus
• ii : In Plane Stress Factor
• t : Stress Check Wall Thickness
• tn : Pipe Wall Thickness

Calculate pipeline SMYS, SMTS, SMTS over SMYS ratio and SMYS over SMTS ratio from pipe stress tables.

Select one of the API, ASME or DNV stress table options. The API stress values are taken from API 5L tables 6 and 7 (note the API 5L X series is superseded). The ASME stress values are taken from ASME B31.3 process piping table A-1M. The DNV stress values are taken from DNVGL ST F101 submarine pipelines, tables 7-5 and 7-11.

Use the Result Table option to display the stress values for the selected stress table (click the Result Table button, and then click the make table button).

Tool Input

• syutype : Stress Table Type
• mattype : Material Type
  • SMYSu : User Defined Specified Minimum Yield Stress
  • SMTSu : User Defined Specified Minimum Tensile Stress

Tool Output

• SMTS : Specified Minimum Tensile Stress
• SMTS/SMYS : Tensile Stress Over Yield Stress Ratio
• SMYS : Specified Minimum Yield Stress
• SMYS/SMTS : Yield Stress Over Tensile Stress Ratio

Calculate pipeline diameter, pressure design wall thickness (nominal wall thickness minus fabrication allowance and corrosion allowance), and minimum wall thickness (nominal wall thickness minus fabrication allowance) from nominal wall thickness.

Select the pipe schedule (NPS or ISO etc), pipe diameter and wall thickness, or use the user defined option. Use the Result Table option to display the pipe schedule with nominal wall thickness, minimum wall thickness and pressure design wall thickness for the selected diameter.

Tool Input

• schdtype : Schedule Type
• diamtype : Diameter Type
  • ODu : User Defined Outside Diameter
  • IDu : User Defined Inside Diameter
• wtntype : Wall Thickness Type
  • tnu : User Defined Wall Thickness
• ttoltype : Wall Thickness Fabrication Tolerance Type
  • txu : User Defined Negative Wall Thickness Fraction
  • tfu : User Defined Negative Wall Thickness Allowance
• c : Wall Thickness Corrosion Allowance

Tool Output

• ID : Nominal Inside Diameter
• OD : Nominal Outside Diameter
• OD/tn : Diameter Over Wall Thickness Ratio
• tf : Wall Thickness Fabrication Allowance
• tm : Minimum Wall Thickness
• tn : Nominal Wall Thickness
• tp : Pressure Design Wall Thickness
• tx : Wall Thickness Fabrication Fraction

Calculate typical line pipe elastic modulus, shear modulus, bulk modulus, density, and thermal expansion coefficient.

The table values of Poisson ratio and bulk modulus are calculated from the elastic modulus and shear modulus. Project specific data should be used if it is available. Use the Result Table option to display a table of properties versus material type.

Tool Input

• modptype : Material Type
  • Eu : User Defined Elastic Modulus
  • Gu : User Defined Shear Modulus
  • Ku : User Defined Bulk Modulus
  • νu : User Defined Poisson Ratio
  • ρu : User Defined Density
  • αu : User Defined Thermal Expansion Coefficient

Tool Output

• α : Thermal Expansion Coefficient
• ν : Poisson Ratio
• ρ : Density
• E : Elastic Modulus
• G : Shear Modulus
• K : Bulk Modulus