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ASME B31.8 Gas Pipeline Design Pressure

Calculate ASME B31.8 gas pipeline maximum allowable design pressure from allowable stress and pressure design wall thickness.

For onshore pipelines and offshore platform piping the allowable pressure is the maximum allowable design pressure for the pipeline location class and facility type. For submerged offshore pipelines the allowable pressure is the maximum allowable pressure difference (internal pressure minus external pressure). Use the Result Table option on the plot bar to display the allowable pressure for the selected pipe diameter.

Reference : ANSI/ASME B31.8 : Gas Transmission And Distribution Piping Systems (2018)

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CALCULATOR : ASME B31.8 Metal Pipe Diameter And Wall Thickness Schedule [FREE]   ±

Calculate ASME B31.8 metal pipe diameter and pressure design wall thickness from pipe schedule or user defined diameter and wall thickness (ASME B31.8 section 841.1). For ASME B31.8 the fabrication tolerance is accounted for in the design factor. The fabrication tolerance is ignored when calculating the pressure design thickness. The pressure design thickness equals the nominal thickness minus the corrosion allowance.

Select the pipe schedule (NPS or ISO), 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 and pressure design wall thickness for the selected diameter. Fabrication tolerance 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 : ASME B31.8 Pipeline Design Pressure (General) [FREE]   ±

Calculate ASME B31.8 general pipe design pressure from diameter, wall thickness and design stress.

The hoop stress is equal to the design stress at the design pressure. For submerged pipelines, the internal design pressure accounts for external pressure (use the include external pressure option). For ASME B31.8 pipe use either the Barlows equation outside diameter option, or the Barlows equation midwall diameter option. Wall thickness tolerance is not required (use the zero wall thickness tolerance option). The corrosion allowance should include mechanical allowance (eg threads), erosion allowance and any other allowances. External pressure should be ignored for onshore pipelines (use the no external pressure option).

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 : ASME B31.8 Section 841.1 Pipeline Design Pressure (Onshore) [FREE]   ±

Calculate onshore pipeline maximum allowable design pressure from allowable hoop stress (ASME B31.8 section 841.1).

The allowable pressure is the maximum allowable local internal pressure for the pipeline location class and facility type. Internal pressure varies with elevation and fluid density. Use the Result Table option to display the allowable pressure for the selected diameter.

Tool Input

  • schdtype : Line 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 : Line Pipe Stress Type
  • mattype : Material Type
    • SMYSu : User Defined Specified Minimum Yield Stress
  • efactype : Weld Joint Quality Factor Type
    • Eu : User Defined Quality Factor
  • tfactype : Temperature Derating Factor Type
    • Td : Design Temperature
    • Tu : User Defined Temperature Derating Factor
  • loctype : Location Class
    • Fu : User Defined Design Stress Factor
  • pipetype : Pipe Section Type
  • satype : Allowable Stress Type
    • Sau : User Defined Allowable Stress
  • ta : Corrosion Allowance

Tool Output

  • D : Pipe Outside Diameter
  • D/tn : Pipe Diameter Over Wall Thickness Ratio
  • E : Weld Joint Factor
  • F : Design Stress Factor
  • PR : Rated Pressure
  • SEFT : Allowable Stress
  • SMYS : Yield Stress
  • T : Temperature Reduction Factor
  • d : Pipe Inside Diameter
  • t : Pipe Pressure Containment Wall Thickness
  • tn : Pipe Nominal Wall Thickness
CALCULATOR : ASME B31.8 Section A842.2 Pipeline Design Pressure (Offshore) [FREE]   ±

Calculate offshore pipeline maximum allowable design pressure from allowable hoop stress (ASME B31.8 annex A842.2).

For platform piping the allowable pressure is the maximum allowable local internal pressure. For subsea pipelines the allowable pressure is the maximum allowable local pressure difference (internal pressure minus the external pressure). Internal and external pressure vary with elevation and fluid density. Use the Result Table option to display the allowable pressure versus wall thickness for the selected pipe diameter.

Tool Input

  • schdtype : Line 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 : Line Pipe Stress Type
  • mattype : Material Type
    • SMYSu : User Defined Specified Minimum Yield Stress
  • tfactype : Temperature Derating Factor Type
    • Td : Design Temperature
    • Tu : User Defined Temperature Derating Factor
  • loctype : Location Class
    • Fu : User Defined Design Stress Factor
  • satype : Allowable Stress Type
    • Sau : User Defined Allowable Stress
  • calctype : Hoop Stress Type
  • ta : Corrosion Allowance

Tool Output

  • D : Pipe Outside Diameter
  • D/tn : Pipe Diameter Over Wall Thickness Ratio
  • F : Design Stress Factor
  • PR : Rated Pressure
  • SFT : Allowable Stress
  • SMYS : Yield Stress
  • T : Temperature Reduction Factor
  • d : Pipe Inside Diameter
  • t : Pipe Pressure Containment Wall Thickness
  • tn : Pipe Nominal Wall Thickness
CALCULATOR : ASME B31.8 Section 841.1 Pipeline Temperature Derated Yield Stress And Tensile Stress [FREE]   ±

Calculate temperature derating factor, and derated yield stress and tensile stress from temperature (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
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