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ASME B31G Level 2 Defect Assessment

Calculate ASME B31G level 2 corrosion defect assessment for blunt type defects.

The level 2 assessment calculates the allowable pressure from the defect "river bottom" profile using the effective area method (also known as the RSTRENG method). Pressure derating is required if the allowable pressure is less than the maximum operating pressure.

The flow stress can be calculated as either 1.1 x SMYS, SMYS + 69 MPa, or 1/2 (SMYS + SMTS). For pipelines operating at high temperature, the SMYS and SMTS should be derated.

For submerged pipelines, or to calculate the allowable pressure at a reference elevation, use the level 1 and level 2 calculators including elevation. The allowable local pressure is calculated including external pressure (use the external pressure = 0 for dry pipelines). The allowable reference pressure is calculated from the local allowable pressure, and the relative elevation.

ASME B31G is suitable for blunt defects of all types, including corrosion, mechanical damage and grinding repairs etc. For crack type defects the NG-18 crack defect calculators are recommended. The effective area method can also be used for blunt defects.

Reference : ANSI/ASME B31G Manual For Determining The Remaining Strength Of Corroded Pipelines (2012)

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CALCULATOR : ASME B31G Section 2.3 Level 2 Corrosion Defect Assessment [PLUS]   ±

Calculate the level 2 corrosion assessment and allowable pressure from the corrosion profile (ASME B31G section 2.3).

Elevation is ignored. Enter the defect profile data as comma separated pairs (x position, defect depth), with each pair on a new line. The defect profile can also be copied and pasted from a spreadsheet, or as tab separated pairs. The data points must be in ascending x order, but do not have to be evenly spaced. Use the Result Plot option to display the defect profile and critical defect. The calculation results for each step are tabled at the bottom of the page (output view).

The level 2 assessment can be used for defects which have failed the level 1 assessment.

Tool Input

  • schdtype : Schedule Type
  • diamtype : Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tu : User Defined Wall Thickness
  • syutype : Stress Table Type
  • mattype : Material Type
    • SMYSu : User Defined Specified Minimum Yield Stress
    • SMTSu : User Defined Specified Minimum Tensile Stress
  • sflowtype : Flow Stress Type
    • Sflowu : User Defined Flow Stress
  • sfactype : Safety Factor Type
    • SFu : User Defined Safety Factor
  • Xdata : X Position Data Along Defect Profile
  • Ddata : Defect Depth Data Along Defect Profile

Tool Output

  • ID : Pipe Inside Diameter
  • M : Critical Defect z Value
  • OD : Pipe Outside Diameter
  • Pa : Maximum Allowable Pressure
  • Pb : Burst Pressure
  • Pf : Failure Pressure
  • S : Flow Stress
  • SF : Safety Factor
  • SMTS : Specified Minimum Tensile Stress
  • SMTS/SMYS : Tensile Stress Over Yield Stress Ratio
  • SMYS : Specified Minimum Yield Stress
  • Z : Critical Defect Z Factor
  • d/t : Critical Defect Depth Over Wall Thickness Ratio
  • dc : Critical Defect Depth
  • dmax : Maximum Defect Depth
  • ic : Critical Defect i Value
  • jc : Critical Defect j Value
  • lc : Critical Defect Length
  • t : Pipe Wall Thickness
  • tmin : Minimum Remaining Wall Thickness

CALCULATOR : ASME B31G Section 2.3 Level 2 Corrosion Defect Assessment Including Elevation [PLUS]   ±

Calculate the level 2 corrosion assessment and pressure derating from the corrosion profile (ASME B31G section 2.3).

Enter the defect profile data as comma separated pairs (x position, defect depth), with each pair on a new line. The defect profile can also be copied and pasted from a spreadsheet, or as tab separated pairs. The calculation results for each step are tabled at the bottom of the page (output view). The local internal and external pressure, and the reference pressure are calculated from elevation.

The level 2 assessment can be used for defects which have failed the level 1 assessment.

Tool Input

  • schdtype : Schedule Type
  • diamtype : Diameter Type
    • ODu : User Defined Outside Diameter
    • IDu : User Defined Inside Diameter
  • wtntype : Wall Thickness Type
    • tu : User Defined Wall Thickness
  • plitype : MOP Pressure Type
    • ρf : Internal Fluid Density
    • Zr : Reference Elevation Relative To Datum
    • Zl : Local Elevation Relative To Datum
  • pletype : External Pressure Type
    • Pleu : User Defined Local External Pressure
    • ρe : External Fluid Density
    • Zs : Surface Elevation Relative To Datum
  • syutype : Stress Table Type
  • mattype : Material Type
    • SMYSu : User Defined Specified Minimum Yield Stress
    • SMTSu : User Defined Specified Minimum Tensile Stress
  • sflowtype : Flow Stress Type
    • Sflowu : User Defined Flow Stress
  • sfactype : Safety Factor Type
    • SFu : User Defined Safety Factor
  • Xdata : X Position Data Along Defect Profile
  • Ddata : Defect Depth Data Along Defect Profile

Tool Output

  • ID : Pipe Inside Diameter
  • M : Critical Defect z Value
  • OD : Pipe Outside Diameter
  • Pb : Burst Pressure
  • Pf : Failure Pressure At Local Elevation
  • Pla : Allowable Pressure Local Elevation
  • Ple : External Pressure At Local Elevation
  • Pra : Allowable Pressuure At Reference Elevation
  • S : Flow Stress
  • SF : Safety Factor
  • SMTS : Specified Minimum Tensile Stress
  • SMTS/SMYS : Tensile Stress Over Yield Stress Ratio
  • SMYS : Specified Minimum Yield Stress
  • Z : Critical Defect Z Factor
  • d/t : Critical Defect Depth Over Wall Thickness Ratio
  • dc : Critical Defect Depth
  • dmax : Maximum Defect Depth
  • ic : Critical Defect i Value
  • jc : Critical Defect j Value
  • lc : Critical Defect Length
  • t : Pipe Wall Thickness
  • tmin : Minimum Remaining Wall Thickness

CALCULATOR : ASME B31G Section 2.1 Level 0 Corrosion Defect Screening Assessment [FREE]   ±

Calculate the level 0 defect assessment and allowable defect length from the maximum defect depth (ASME B31G section 2.1). The allowable defect length is based on the original B31G method. The level 0 assessment may be used as an initial screening assessment. Defects which fail the level 0 assessment require further assessment, or repair.

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
  • L : Defect Length
  • d : Defect Maximum Depth

Tool Output

  • B : Defect B Value
  • Ba : Defect Allowable B Value
  • ID : Pipe Inside Diameter
  • La : Defect Allowable Length
  • OD : Pipe Outside Diameter
  • d/t : Defect Depth Over Wall Thickness Ratio
  • t : Pipe Wall Thickness
  • tmin : Defect Minimum Remaining Wall Thickness

CALCULATOR : ASME B31G Section 1.7 Flow Stress [FREE]   ±

Calculate the flow stress from SMYS and SMTS (ASME B31G section 1.7 : ASME B31.8).

For temperatures above 120 C the yield stress and tensile stress should be derated. The derating factors are valid upto 232 C (450 F) only. For temperatures above 232 C (450 F) use material specific data. The derating factor is assumed to be valid for yield stress and tensile stress.

Reference : ANSI/ASME B31.8 : Gas Transmission And Distribution Piping Systems : section 841.1 table 841.1.8-1

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 Reduction Factor
  • sflowtype : Flow Stress Type
    • Sfu : User Defined Flow Stress

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
  • Sf : Flow Stress
  • Su : Derated Tensile Stress
  • Sy : Derated Yield Stress
  • T : Temperature Derating Factor

CALCULATOR : ASME B31G Pipe Diameter From Circumference [FREE]   ±

Calculate pipe outside diameter from circumference, or pipe circumference from outside diameter for ASME B31G.

Use either the nominal pipe diameter and wall thickness, or the measured pipe diameter and wall thickness for the ASME B31G checks.

Tool Input

  • odtype : Pipe Outside Diameter Measurement Type
    • ODu : Measured Outside Diameter
    • OCu : Measured Outside Circumference

Tool Output

  • OC : Pipe Outside Circumference
  • OD : Pipe Outside Diameter

CALCULATOR : ASME B31G Section 1.7 Derated Yield Stress And Tensile Stress [FREE]   ±

Calculate the derated yield stress, ultimate stress and flow stress for steel pipelines operating above 120 C (ASME B31G section 1.7 : ASME B31.8).

The derating factors are valid upto 232 C (450 F) only. For temperatures above 232 C (450 F) use material specific data. The derating factor is assumed to be valid for yield stress and tensile stress.

Reference : ANSI/ASME B31.8 : Gas Transmission And Distribution Piping Systems : section 841.1 table 841.1.8-1

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