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API RP 1111 Pipeline Wall Thickness

Calculate API RP 1111 limit state pipeline wall thickness from local pressure.

The pipe wall thickness should be calculated for the maximum pressure difference at all points on the pipeline or pipeline section. Internal pressure is calculated from reference pressure and elevation. The internal fluid density is assumed constant. External pressure should be calculated for the minimum local water depth (lowest astronomical tide and allowance for storm surge etc). API RP 1111 should only be used for line pipe with a weld joint factor = 1.0.

Note : The derated yield stress and tensile stress are used in the API RP 1111 calculations.

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 Wall Thickness From Design Pressure And Elevation [PLUS]   ±

Calculate pipe wall thickness from design pressure and elevation (API RP 1111 section 4.3.1).

Pipe diameter can be either user defined OD (constant OD), or user defined ID (constant ID). Wall thickness can be calculated using either equation 4, or equation 5, or can be specified. Wall thickness should be calculated for all elevations. Use the Result Plot option to plot the calculated wall thickness versus elevation. Normally a standard pipe thickness will be selected which is greater than or equal to the maximum required wall thickness (for elevation).

Tool Input

  • pletype : Local External Pressure Type
    • Pleu : User Defined Local External Pressure
  • plitype : Local Internal Pressure (MOP) Type
    • Priu : User Defined MOP At Reference Elevation
    • Pliu : User Defined MOP 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
  • walltype : Wall Thickness Type
  • loctype : Location Type
    • Fdu : User Defined Internal Pressure Design Factor
  • calctype : Wall Thickness Calculation Type
  • tc : Corrosion Allowance
  • Td : Design Temperature
  • ρi : Internal Fluid Density
  • ρe : External Fluid Density
  • Zr : Reference Elevation
  • Zl : Local Elevation
  • Zs : Surface Elevation

Tool Output

  • ΔPl : Delta Pressure Across Pipe Wall
  • Fd : Internal Pressure Design Factor
  • ID : Nominal Inside Diameter
  • OD : Nominal Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • PR : Rated Pressure
  • Pb : Temperature Derated Burst Pressure
  • Ple : External Pressure
  • Pli : Local Internal Pressure
  • Sa : Allowable Stress
  • Sb : Temperature Derated Burst Stress
  • Sh : Hoop Stress
  • Su : Temperature Derated Tensile Stress
  • Sy : Temperature Derated Yield Stress
  • ft : Temperature Derating Factor (ASME B31.8)
  • th : Pressure Containment Wall Thickness
  • tn : Nominal Wall Thickness
  • wd : Water Depth

CALCULATOR : API RP 1111 Pipeline Wall Thickness From Hoop Stress (General) [FREE]   ±

Calculate API RP 1111 general pipeline wall thickness from diameter and design stress.

For API RP 1111 pipe, select either the Barlow's equation midwall diameter option, or the log equation option. The manufacturing tolerance is ignored (set the manufacturing tolerance to zero). The corrosion allowance should include mechanical allowance (eg threads), erosion allowance and any other allowances.

Tool Input

  • pletype : External Pressure Type
    • Peu : User Defined External Pressure
  • 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
  • syutype : Stress Table Type
  • mattype : Yield Stress Type
    • SMYSu : User Defined Specified Minimum Yield Stress
  • sdtype : Design Stress Type (F x SMYS)
    • Fu : User Defined Design Factor
    • Sdu : User Defined Design Stress
  • walltype : Wall Thickness Calculation Type
    • Yu : User Defined ASME Y Factor
  • calctype : Wall Thickness Type
  • tc : Corrosion Allowance
  • Pi : Internal Pressure

Tool Output

  • ID : Pipe Inside Diameter
  • OD : Pipe Outside Diameter
  • OD/tn : Pipe Diameter Over Wall Thickness Ratio
  • PΔ : Pressure Difference
  • Pe : External Pressure
  • SMYS : Specified Minimum Yield Stress
  • Sd : Design Stress
  • Sh : Pipe Hoop Stress
  • Sh/Sd : Hoop Stress Over Design Stress Ratio
  • cvg : Convergence Check
  • tf : Fabrication Allowance
  • tfx : Fabrication Fraction
  • th : Hoop Stress Thickness (Pressure Containment)
  • tm : Minimum Wall Thickness
  • tn : Nominal Wall Thickness
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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