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API RP 1111 Pipeline Design Pressure

Calculate API RP 1111 limit state pipeline maximum allowable design pressure from wall thickness and burst stress.

Burst stress is calculated from the average of the yield stress and the ultimate tensile stress. Burst pressure can be calculated from either equation 4, or equation 5. The maximum test pressure, incidental pressure and design pressure are calculated from the burst pressure. The allowable pressure is calculated so that the hoop stress equals the allowable stress. For submerged pipelines the allowable pressure equals the pressure difference (internal pressure minus external pressure).

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 Pipeline Design Pressure (General) [FREE]   ±

Calculate ASME B31.3 general pipeline design pressure from diameter, wall thickness and design stress.

The hoop stress is equal to the design stress at the design pressure. The design internal pressure includes the effect of external pressure.

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 : Hoop Stress Calculation Type
    • Yu : User Defined ASME Y Factor
  • tc : Corrosion Allowance

Tool Output

  • ID : Pipe Inside Diameter
  • OD : Pipe Outside Diameter
  • OD/tn : Pipe Diameter Over Wall Thickness Ratio
  • Pd : Design Internal Pressure
  • PdΔ : Design Delta Pressure
  • Pe : External Pressure
  • SMYS : Specified Minimum Yield Stress
  • Sd : Design Stress
  • 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
CALCULATOR : API RP 1111 Section 4.3.1 Pipeline Maximum Design Pressure From Wall Thickness [FREE]   ±

Calculate pipeline maximum allowable design pressure from wall thickness and the temperature derated burst stress (API RP 1111 section 4.3.1).

Burst pressure can be calculated using either equation 4, or equation 5. The maximum pressure is the maximum pressure difference across the pipe wall (internal pressure minus external pressure). For subsea pipelines the allowable internal pressure equals the maximum pressure plus the external pressure. The allowable pressure is calculated so that the hoop stress equals the allowable stress. Use the Result Table option to display a table of maximum pressure versus wall thickness for the selected pipe schedule.

Tool Input

  • 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
  • loctype : Internal Pressure Design Factor Type
    • Fdu : User Defined Internal Pressure Design Factor
  • calctype : Burst Pressure Calculation Type
  • tc : Corrosion Allowance
  • Td : Design Temperature

Tool Output

  • D/t2 : Pipe Diameter Over Wall Thickness Ratio
  • Fd : Internal Pressure Design Factor
  • Ft : Temperature Derating Factor (ASME B31.8)
  • ID : Nominal Inside Diameter
  • OD : Nominal Outside Diameter
  • PR : Maximum Design Pressure Difference Or Rated Pressure
  • Pb : Temperature Derated Burst Pressure
  • Pi : Maximum Incidental Pressure Difference
  • Pt : Maximum Test Pressure Difference
  • Sb : Temperature Derated Burst Stress
  • Su : Temperature Derated Tensile Stress
  • Sy : Temperature Derated Yield Stress
  • th : Pressure Containment Wall Thickness
  • tn : Nominal Wall Thickness
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