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ASME B31.8 Gas Pipeline Hydrotest Pressure

Calculate ASME B31.8 gas pipeline test pressure and hoop stress check for onshore and offshore pipelines.

Select the appropriate line pipe schedule (ASME or ISO etc), and stress table (API, ASME or DNV), or use the user defined options. For metal pipeline the pressure design thickness equals the nominal wall thickness minus the corrosion allowance. Fabrication tolerance is ignored. Pipe pressure can either be calculated from elevation, or user defined. The test pressure should be checked for all pipeline elevations. A test point test pressure should be specified which is greater than or equal to the maximum calculated test pressure (usually by rounding up the maximum test pressure). Use the Result Plot option to plot the test pressure versus elevation, and the hoop stress versus elevation for the specified test pressure.

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

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CALCULATOR : ASME B31.8 Section 841.3 Pipeline Test Pressure And Hoop Stress Check (Onshore) [PLUS]   ±

Calculate onshore steel pipeline test pressure and hoop stress from maximum operating pressure (ASME B31.8 section 841.3).

The test pressure is calculated from the maximum operating pressure (MOP). For retesting of existing pipelines refer to table 845.2.2-1, table 845.2.3-1, and table 845.2.3-2.

Note : The pressure test factors were changed in ASME B31.8 2010. The calculator includes an option for retest of old pipelines prior to 2010 using the old test factors. Engineering judgement is required.

Tool Input

  • plitype : Internal Pressure Type
    • Priu : User Defined Reference Internal Pressure
    • Pliu : User Defined Local Internal Pressure
    • ρf : Internal Fluid Density
    • Zr : Reference Elevation
    • Zl : Local Elevation
  • syutype : Line Pipe Stress Type
  • mattype : Material Type
    • SMYSu : User Defined Specified Minimum Yield Stress
  • satype : Allowable Stress Type
    • Fu : User Defined Design Stress Factor
    • Sau : User Defined Allowable Stress
  • 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
  • tfactype : Test Pressure Factor Type
    • Tu : User Defined Test Pressure Factor
  • loctype : Location Class
  • testtype : Test Pressure Type
    • Pltu : User Defined Local Test Pressure
    • Pttu : User Defined Test Point Test Pressure
    • Zt : Test Point Elevation
    • ρt : Test Fluid Density
  • calctype : Hoop Stress Equation Type
  • walltype : Hoop Stress Wall Thickness Type
  • ta : Corrosion Allowance

Tool Output

  • D/tn : Pipe Diameter Over Wall Thickness Ratio
  • ID : Pipe Inside Diameter
  • OD : Pipe Outside Diameter
  • Pli : Internal Fluid Pressure
  • Plt : Local Test Pressure
  • Plt/Pli : Local Test Pressure Over Operating Pressure Ratio
  • Pltmin : Minimum Required Local Test Pressure
  • Ptt : Test Point Test Pressure
  • SEFT : Allowable Stress
  • SMYS : Yield Stress
  • Sh : Hoop Stress
  • Sh/Sa : Hoop Stress Ratio
  • T : Test Pressure Factor
  • t* : Wall Thickness For Hoop Stress Calculation
  • th : Pipe Pressure Containment Wall Thickness
  • tn : Pipe Nominal Wall Thickness

CALCULATOR : ASME B31.8 Section A847.2 Pipeline Test Pressure And Hoop Stress Check (Offshore) [PLUS]   ±

Calculate offshore steel pipeline test pressure and hoop stress from maximum operating pressure (ASME B31.8 section A847.2). The test pressure is calculated from the maximum operating pressure (MOP). For offshore platform piping the external pressure should be set to zero.

Tool Input

  • plitype : Internal Pressure Type
    • Priu : User Defined Reference Internal Pressure
    • Pliu : User Defined Local Internal Pressure
    • ρf : Internal Fluid Density
    • Zr : Reference Elevation
    • Zl : Local Elevation
  • pletype : External Pressure Type
    • Pleu : User Defined Local External Pressure
    • ρe : External Fluid Density
    • Zs : Surface Elevation
  • syutype : Line Pipe Stress Type
  • mattype : Material Type
    • SMYSu : User Defined Specified Minimum Yield Stress
  • satype : Allowable Stress Type
    • Fu : User Defined Design Stress Factor
    • Sau : User Defined Allowable Stress
  • 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
  • tfactype : Test Pressure Factor Type
    • Tu : User Defined Test Pressure Factor
  • testtype : Test Pressure Type
    • Pltu : User Defined Local Test Pressure
    • Pttu : User Defined Test Point Test Pressure
    • Zt : Test Point Elevation
    • ρt : Test Fluid Density
  • calctype : Hoop Stress Equation Type
  • walltype : Hoop Stress Wall Thickness Type
  • ta : Corrosion Allowance

Tool Output

  • ΔPl : Delta Test Pressure Across Pipe Wall
  • D/tn : Pipe Diameter Over Wall Thickness Ratio
  • ID : Pipe Inside Diameter
  • OD : Pipe Outside Diameter
  • Ple : External Fluid Pressure
  • Pli : Internal Fluid Pressure
  • Plt : Local Test Pressure
  • Pltmin : Minimum Required Local Test Pressure
  • Pt/Pli : Local Test Pressure Over Operating Pressure Ratio
  • Ptt : Test Point Test Pressure
  • SFT : Allowable Stress
  • SMYS : Yield Stress
  • Sh : Hoop Stress
  • Sh/S : Hoop Stress Ratio
  • T : Test Pressure Factor
  • t* : Wall Thickness For Hoop Stress Calculation
  • th : Pipe Pressure Containment Wall Thickness
  • tn : Pipe Nominal Wall Thickness

CALCULATOR : ASME B31.8 Section 842.5 Plastic Pipe Test Pressure And Hoop Stress Check [FREE]   ±

Calculate plastic pipe test pressure and hoop stress from maximum operating pressure (ASME B31.8 section 842.5).

The test pressure for thermoset plastic pipes shall not exceed 3 times the design pressure. For thermoplastic plastic pipe, the leak test pressure shall not exceed 3 times the design pressure for pipes operating below 100 degrees Fahrenhite, or 2 times the design pressure for pipes operating above 100 degrees Fahrenhite.

Tool Input

  • schdtype : Pipe Schedule Type
  • diamtype : Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tnu : User Defined Wall Thickness
    • DRu : User Defined Dimension Ratio SDR OR SIDR
  • walltype : Hoop Stress Wall Thickness Type
  • tfactype : Test Pressure Factor Type
    • Tu : User Defined Test Pressure Factor
  • testtype : Test Pressure Type
    • Ptu : User Defined Test Pressure
  • HDB : Hydrostatic Design Basis Stress
  • c : Mechanical Allowance
  • P : Design Pressure

Tool Output

  • CVG : Convergence Factor
  • D : Pipe Outside Diameter
  • DR : Dimension Ratio (SDR or SIDR)
  • Phdb : HDB Test Pressure
  • Pt : Test Pressure
  • Pt/Pli : Test Pressure Over Operating Pressure Ratio
  • Sh : Hoop Stress
  • Sh/HDB : Hoop Stress Over Allowable Stress Ratio (≤ 1)
  • T : Test Pressure Factor
  • d : Pipe Inside Diameter
  • t : Wall Thickness For Hoop Stress Calculation
  • th : Pressure Containment Wall Thickness
  • tn : Nominal Wall Thickness

CALCULATOR : ASME B31.8 Pipeline Hydrotest Liquid Volume And Dose Rate [FREE]   ±

Calculate ASME B31.8 water volume and liquid chemical dose rate for water hydrotest.

The dose rate can be calculated from the dose volume fraction, the dose mass fraction, the dose volume ratio, or the dose mass ratio. The average fluid density includes the dose chemical. The calculated volume does not include the effect of fluid compression or pipe expansion due to the test pressure.

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
  • dosetype : Dosage Type
    • Xvu : User Defined Dose Volume Fraction
    • Xmu : User Defined Dose Mass Fraction
    • Rvu : User Defined 200
    • Rmu : User Defined 250
  • voltype : Fluid Volume Type
    • Vlu : User Defined Liquid Volume
    • Mlu : User Defined Liquid Mass
    • Vfu : User Defined Total Fluid Volume
    • Mfu : User Defined Total Fluid Mass
    • Lu : User Defined Pipeline Length
  • ρl : Liquid Density
  • ρd : Dose Chemical Density

Tool Output

  • ρf : Fluid Average Density
  • ID : Inside Diameter
  • L : Pipe Length
  • Md : Dose Mass
  • Mf : Total Fluid Mass
  • Ml : Liquid Mass
  • Rm : Dose Mass Ratio
  • Rv : Dose Volume Ratio
  • Vd : Dose Volume
  • Vf : Total Fluid Volume
  • Vl : Liquid Volume
  • Xm : Dose Mass Fraction
  • Xv : Dose Volume Fraction
CALCULATOR : ASME B31.8 Pipeline Leak Test Gas Volume And Dose Rate [FREE]   ±

Calculate ASME B31.8 gas volume and liquid chemical dose rate for gas leak test.

The dose rate can be calculated from dose volume fraction, dose mass fraction or dose gas ratio. The average fluid density includes the dose chemical. The calculated volume does not include the effect of pipe expansion due to the test pressure.

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
  • dosetype : Dose Rate Type
    • Xvu : User Defined Dose Volume Fraction
    • Xmu : User Defined Dose Mass Fraction
    • Rvu : User Defined Dose Volume Over Gas Moles Ratio
    • Rmu : User Defined Dose Mass Over Gas Moles Ratio
  • voltype : Fluid Volume Type
    • Vgu : User Defined Gas Volume
    • Mgu : User Defined Gas Mass
    • Ngu : User Defined Gas Moles
    • Vfu : User Defined Total Fluid Volume
    • Mfu : User Defined Total Fluid Mass
    • Lu : User Defined Pipeline Length
  • ρd : Dose Chemical Density
  • P : Fluid Pressure
  • T : Fluid Temperature
  • Z : Gas Compressibility Factor
  • SG : Gas Specific Gravity

Tool Output

  • ρf : Fluid Average Density
  • ρg : Gas Density (At T P)
  • ID : Inside Diameter
  • L : Pipe Length
  • Md : Dose Mass
  • Mf : Total Fluid Mass
  • Mg : Gas Mass
  • Ng : Gas Moles
  • Rm : Dose Mass Over Gas Moles Ratio
  • Rv : Dose Volume Over Gas Moles Ratio
  • Vd : Dose Volume
  • Vf : Total Fluid Volume
  • Vg : Gas Volume
  • Xm : Dose Mass Fraction
  • Xv : Dose Volume Fraction
  • vg : Gas Mole Volume (At T P)
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 Plastic Pipe Diameter And Wall Thickness Schedule [FREE]   ±

Calculate ASME B31.8 plastic pipe diameter and pressure design wall thickness from pipe schedule or user defined diameter and wall thickness (ASME B31.8 section 842.2).

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 results for the selected diameter. Fabrication tolerance is included.

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
    • DRu : User Defined Dimension Ratio SDR OR SIDR
  • ttoltype : Wall Thickness Fabrication Tolerance Type
    • xfu : User Defined Negative Wall Thickness Fraction
    • tfu : User Defined Negative Wall Thickness Allowance
  • c : Wall Thickness Mechanical Allowance

Tool Output

  • CVG : Convergence Factor
  • DR : Pipe Dimension Ratio (SDR Or SIDR)
  • ID : Nominal Inside Diameter
  • OD : Nominal Outside Diameter
  • tf : Wall Thickness Fabrication Allowance
  • tm : Minimum Wall Thickness
  • tn : Nominal Wall Thickness
  • tp : Pressure Design Wall Thickness
CALCULATOR : ASME B31.8 Pipeline Test Pressure And Hoop Stress Check (General) [FREE]   ±

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

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
  • 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
  • schdtype : Pipe Schedule Type
  • diamtype : Pipe Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • sdtype : Design Stress Type (F x SMYS)
    • Fu : User Defined Design Factor
    • Sdu : User Defined Design Stress
  • walltype : Hoop Stress Wall Thickness Type
    • Yu : User Defined ASME Y Factor
  • hooptype : Hoop Stress Wall Thickness Type
  • testtype : Test Pressure Type
    • Tu : User Defined Test Factor
    • Ptu : User Defined Test Pressure
  • tc : Corrosion Allowance
  • Pi : Operating Pressure

Tool Output

  • ID : Pipe Inside Diameter
  • OD : Pipe Outside Diameter
  • OD/tn : Pipe Diameter Over Wall Thickness Ratio
  • Pe : External Pressure
  • Pt : Test Pressure
  • PtΔ : Test Pressure Difference
  • SMYS : Specified Minimum Yield Stress
  • Sd : Design Stress
  • Sh : Hoop Stress
  • Sh/SMYS : Hoop Stress Over Yield Stress Ratio
  • T : Test Pressure Factor
  • 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 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
CALCULATOR : ASME B31.8 Section 842.2 Plastic Pipe Allowable Stress [FREE]   ±

Calculate allowable stress (SDf) for plastic piping (ASME B31.8 section 142.2).

The allowable stress equals the hydrostatic design basis (HDB) times the design factor (Df). SDf = HDB x Df.

Tool Input

  • satype : Allowable Stress Type
    • HDB : Hydrostatic Design Basis Stress
    • Dfu : User Defined Design Stress Factor
    • Sau : User Defined Allowable Stress

Tool Output

  • Sa : Allowable Stress
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