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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 : API RP 1111 Section 4.3.1 Pipeline Combined Axial Load And Hoop Stress Check [PLUS]   ±

Calculate pipeline effective axial load from temperature and pressure and stress check (API RP 1111 section 4.3.1).

The axial load ratio should be ≤ 0.6 (in tension). The combined load checks should be ≤ the values in section 4.3.1.2. The von Mises stress check is provided for information (it is not required by the code). Loads are positive in tension, and negative in compression. The installation internal pressure is assumed to be zero.

Tool Input

  • pletype : Local External Pressure Type
    • Pleu : User Defined Local External Pressure
  • plitype : Local Internal Pressure Type
    • Priu : User Defined Internal Pressure At Reference Elevation
    • Pliu : User Defined Internal Pressure At Local Elevation
  • 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
  • syutype : Stress Table Type
  • mattype : Yield Stress Type
    • SMYSu : User Defined Specified Minimum Yield Stress
    • SMTSu : User Defined Specified Minimum Tensile Stress
  • tfactype : Temperature Derating Type
    • ftu : User Defined Temperature Reduction Factor
  • sfactype : Stress Factor Type
    • F4u : User Defined Equation 4 Stress Factor
    • F5u : User Defined Equation 5 Stress Factor
  • modptype : Pipe Material Type
    • νu : User Defined Pipe Poisson's Ratio
    • αu : User Defined Pipe Thermal Expansion Coefficient
    • Eu : User Defined Pipe Elastic Modulus
  • walltype : Corrosion Allowance Type
  • calctype : Hoop Stress Calculation Type
  • checktype : Combined Load Check Type
    • CHKmaxu : User Defined Maximum Combined Load Check
  • sectype : Pipe Section Properties Type
    • Npu : User Defined Plastic Axial Load
    • Asu : User Defined Steel Cross Section Area
    • EAαu : User Defined Pipe E x A x alpha
  • loadtype : Axial Load Type
    • Fgu : User Defined Effective Axial Load
    • Fwu : User Defined Pipe Wall Axial Load
  • tc : Corrosion Allowance
  • Td : Design Temperature
  • Tin : Installation Temperature
  • Fin : Installation Load
  • ρf : Internal Fluid Density
  • ρe : External Fluid Density
  • Zr : Reference Elevation
  • Zl : Local Elevation
  • Zs : Surface Elevation

Tool Output

  • ΔPl : Delta Pressure Across Pipe Wall
  • α : Pipe Thermal Expansion Coefficient
  • ν : Pipe Poisson's Ratio
  • As : Pipe Steel Cross Section Area
  • CHK : Combined Load Ratio
  • CHKmax : Maximum Allowable Check Value
  • E : Pipe Elastic Modulus
  • EAα : Pipe E x A x alpha
  • ID : Pipe Inside Diameter
  • OD : Pipe Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • Pb : Temperature Derated Burst Pressure
  • Ple : External Pressure
  • Pli : Local Internal Pressure
  • Sb : Temperature Derated Burst Stress
  • Sh : Pipe Hoop Stress
  • Su : Temperature Derated Tensile Stress
  • Svm : Von Mises Equivalent Stress
  • Svm/Sb : Von Mises Equivalent Stress Over Burst Stress Ratio
  • Svm/Sy : Von Mises Equivalent Stress Over Yield Stress Ratio
  • Sw : Pipe Wall Axial Stress
  • Sy : Temperature Derated Yield Stress
  • Ta : Pipe Wall Axial Load
  • Teff : Effective Axial Load
  • Teff/Ty : Effective Load Over Yield Load Ratio
  • Ty : Pipe Wall Yield Load
  • ft : Temperature Derating Factor (ASME B31.8)
  • th : Hoop Stress Wall Thickness
  • tn : Nominal Wall Thickness
  • wd : Water Depth

CALCULATOR : API RP 1111 Section 4.3.2 Pipeline Combined External Pressure And Bending Check [PLUS]   ±

Calculate pipeline combined external pressure and bending buckling check (API RP 1111 section 4.3.2). The buckle check (equation 13) has been rearranged so that the check value should be ≤ 1.

Tool Input

  • pletype : Local External Pressure Type
    • Pleu : User Defined Local External Pressure
  • plitype : Local Internal Pressure Type
    • Priu : User Defined Internal Pressure At Reference Elevation
    • Pliu : User Defined Internal Pressure At Local Elevation
  • 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
  • syutype : Stress Table Type
  • mattype : Yield Stress Type
    • SMYSu : User Defined Specified Minimum Yield Stress
  • tfactype : Temperature Derating Type
    • ftu : User Defined Temperature Reduction Factor
  • modptype : Pipe Material Type
    • νu : User Defined Pipe Poisson's Ratio
    • Eu : User Defined Pipe Elastic Modulus
  • walltype : Corrosion Allowance Type
  • pectype : Combined Load Factor Type
    • fcu : User Defined Collapse Factor
  • tc : Corrosion Allowance
  • δ : Pipe API Ovality
  • M : Bending Moment
  • Td : Design Temperature
  • ρf : Internal Fluid Density
  • ρe : External Fluid Density
  • Zr : Reference Elevation
  • Zl : Local Elevation
  • Zs : Surface Elevation

Tool Output

  • ΔPl : Delta External Over Pressure Across Pipe Wall
  • ε : Pipe Bending Strain
  • εb : Buckling Strain (Pure Bending)
  • ν : Pipe Poisson's Ratio
  • CHK : Combined Load Ratio (≤ 1)
  • E : Pipe Elastic Modulus
  • ID : Pipe Inside Diameter
  • OD : Pipe Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • Pc : External Collapse Pressure
  • Pce : Elastic Collapse Pressure
  • Pcy : Plastic Collapse Pressure
  • Ple : External Pressure
  • Pli : Local Internal Pressure
  • Sy : Temperature Derated Yield Stress
  • fc : Combined Load Factor
  • ft : Temperature Derating Factor (ASME B31.8)
  • g(δ) : Collapse Reduction Factor
  • th : Collapse Wall Thickness
  • tn : Nominal Wall Thickness
  • wd : Water Depth

CALCULATOR : API RP 1111 Section 4.3.1 Pipeline Temperature Derated Yield Stress And Tensile Stress [FREE]   ±

Calculate temperature derating factor, and derated yield stress and tensile stress from temperature (API RP 1111 section 4.3.1 and ASME B31.8 section 841.1).

Refer to Table 841.1.8-1 for the derating factors. The derating factors are valid for steel pipe upto 232 C (450 F). For temperatures above 232 C (450 F) the derating values should be used carefully (material specific test data should be used if it is available). The derating factor is assumed to be valid for yield stress and tensile stress. Use the Result Table option to display the results for the selected stress table (API, ASME or DNV). The temperature derating factor is not valid for nickel alloy, or stainless steel.

Tool Input

  • syutype : Stress Table Type
  • mattype : Material Type
    • SMYSu : User Defined Specified Minimum Yield Stress
    • SMTSu : User Defined Specified Minimum Tensile Stress
  • tfactype : Temperature Derating Factor Type
    • Td : Design Temperature
    • Tu : User Defined Temperature Derating Factor

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
  • Su : Derated Tensile Stress
  • Sy : Derated Yield Stress
  • T : Temperature Derating Factor
CALCULATOR : API RP 1111 Pipeline Diameter And Wall Thickness Schedule [FREE]   ±

Calculate API RP 1111 pipeline diameter and wall thickness from pipe schedule.

The pressure design thickness equals the nominal wall thickness minus the corrosion allowance. The corrosion allowance includes mechanical allowances such as threads and damage etc. Use the Result Table option display a table of pressure design wall thickness versus wall thickness for the selected diameter schedule. Fabrication tolerance is included in the design factor and is ignored.

Tool Input

  • schdtype : Line Pipe Schedule Type
  • diamtype : Line Pipe Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Wall Thickness
  • c : Wall Thickness Corrosion Allowance

Tool Output

  • ID : Nominal Inside Diameter
  • OD : Nominal Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • tn : Nominal Wall Thickness
  • tp : Pressure Design Wall Thickness
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