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AGA NG18 Crack Defect

Calculate AGA NG-18 Level 0 critical defect length and minimum required fracture toughness from flow stress and hoop stress.

The level 0 assessment is useful as a screening check for crack defects. The level 0 check is from AS 2885.1. The temperature derating calculation is from ASME B31.8. Material specific test data should be used if it is available. Use the level 1 assessment for simple defects from defect length and depth. Use the level 2 assessment for complex defects from the defect river bottom profile. Refer to the module list below.

AGA NG-18 is suitable for crack defects. For blunt defects including corrosion, mechanical damage and grinding repairs etc the ASME B31G or RSTRENG calculators are recommended.

Reference : AGA Pipeline Research Committee NG-18 Report 204 Ductile Fracture Properties of Selected Linepipe Steels

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CALCULATOR : AGA NG-18 Minimum Charpy Fracture Toughness [FREE]   ±

Calculate AGA NG-18 minimum required Charpy V notch energy (CVN).

The minimum Charpy energy can be calculated using either the AISI (American Iron and Steel Institute), BCL (Battelle Columbus Labs), BGC (British Gas Corporation), or BSC (British Steel Corporation) methods.

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

Tool Input

  • cvntype : Charpy Energy Calculation Type
  • D : Nominal Outside Diameter
  • t : Nominal Wall Thickness
  • S : Hoop Stress

Tool Output

  • CVN : Charpy V Notch Energy
CALCULATOR : AGA NG-18 Level 0 Critical Defect Length And Fracture Toughness [FREE]   ±

Calculate AGA NG-18 level 0 critical defect length and minimum required fracture toughness from flow stress and hoop stress (AS 2885.1). `
`The critical defect length is calculated using the Folias factor Mt. The required fracture toughness and Charpy V notch energy to prevent fracture are calculated from the initiation defect length. The inititation defect length is normally taken as 80% - 90% of the critical defect length.

Reference : Australian Standard AS 2885.1 : Pipelines - Gas And Liquid Petroleum Part 1 : Design And Construction

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
  • ttoltype : Fabrication Tolerance Type
    • xu : User Defined Negative Wall Thickness Fraction
    • Hu : User Defined Negative Wall Thickness Allowance
  • modptype : Pipe Material Type
    • Eu : User Defined Pipe Elastic Modulus
  • idltype : Inititation Defect Length Type
    • Fiu : User Defined Initiation Defect Length Factor
    • IDLu : User Defined Initiation Defect Length
  • G : Corrosion Allowance
  • Sf : Flow Stress
  • Sh : Hoop Stress
  • Ac : Charpy Test Piece Fracture Area

Tool Output

  • CDL : Critical Defect Length
  • CVG : Convergence Factor
  • CVN : Charpy V Notch Fracture Energy
  • E : Young's Modulus
  • H : Wall Thickness Fabrication Allowance
  • ID : Pipe Inside Diameter
  • IDL : Inititation Defect Length (< CDL)
  • Mt : Folias Factor
  • OD : Pipe Outside Diameter
  • OD/tn : Pipe Diameter Over Wall Thickness Ratio
  • Sf/Sh : Flow Stress Over Hoop Stress Ratio (> 1)
  • tm : Minimum Fabrication Wall Thickness
  • tn : Nominal Wall Thickness
  • tw : Pressure Design Wall Thickness
  • xf : Wall Thickness Fabrication Fraction
CALCULATOR : AGA NG-18 Derated Yield Stress And Tensile Stress [FREE]   ±

Calculate the derated yield stress, ultimate stress and flow stress for steel pipelines operating above 120 C for AGA NG-18.

Derating is calculated according to 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
CALCULATOR : AGA NG-18 Pipe Diameter And Wall Thickness Schedule [FREE]   ±

Calculate pipe nominal wall thickness and diameter for AGA NG-18.

The nominal pipe diameter and wall thickness or the measured pipe diameter and wall thickness can be used for the AGA NG-18 checks.

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
  • ttoltype : Wall Thickness Fabrication Tolerance Type
    • txu : User Defined Negative Wall Thickness Fraction
    • tfu : User Defined Negative Wall Thickness Allowance
  • c : Wall Thickness Corrosion Allowance

Tool Output

  • ID : Nominal Inside Diameter
  • OD : Nominal Outside Diameter
  • OD/tn : Diameter Over Wall Thickness Ratio
  • tf : Wall Thickness Fabrication Allowance
  • tm : Minimum Wall Thickness
  • tn : Nominal Wall Thickness
  • tp : Pressure Design Wall Thickness
  • tx : Wall Thickness Fabrication Fraction
CALCULATOR : AGA NG-18 Pipe Diameter From Circumference [FREE]   ±

Calculate pipe outside diameter from circumference, or pipe circumference from outside diameter for AGA NG-18.

Use either the nominal pipe diameter and wall thickness, or the measured pipe diameter and wall thickness for the AGA NG-18 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
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