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PRCI PR 3805 RSTRENG Level 2 RSTRENG Method

Calculate the PR-3-805 RSTRENG level 2 (RSTRENG Method) corrosion defect assessment for blunt defects.

Use the level 2 calculators to calculate 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 measured pipe diameter and wall thickness should be used in the calculations.

The calculators which include elevation can be used to include external pressure, and to calculate the allowable pressure at a reference elevation (for Example to calculate the allowable pressure at the pressure control location). Set the external pressure = 0 for dry pipelines.

For pipelines operating above 120 C the yield stress and ultimate stress should be derated . Use the stress derating calculator if test data is not available. Test data should be used if it is available.

PR-3-805 RSTRENG is suitable for blunt corrosion defects and mechanical damage defects (eg from grinding). ASME B31G is also suitable for blunt defects. AGA NG-18 is suitable for crack type defects. Flow stress can be calculated using either the RSTRENG equation, or the ASME equation.

Reference : PRCI, Pipeline Research Committee Project, PR-3-805, “A Modified Criterion for Evaluating the Remaining Strength of Corroded Pipe,” December 22, 1989, PRCI PR-3-805 (R-STRENG) With RSTRENG Disk.

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CALCULATOR : PR-3-805 RSTRENG Level 2 Corrosion Defect Assessment [PLUS]   ±

Calculate PR-3805 RSTRENG level 2 blunt defect allowable pressure from the defect profile. Elevation is ignored. The external pressure is assumed equal to zero.

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 : PR-3-805 RSTRENG Level 2 Corrosion Defect Assessment Including Elevation [PLUS]   ±

Calculate PR-3805 RSTRENG level 2 blunt defect local allowable pressure and reference allowable pressure from the defect profile and elevation.

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). Use the Result Plot option to display the defect profile and critical defect. The data points must be in ascending x order, but do not have to be evenly spaced.

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 : PR-3-805 RSTRENG Level 0 Corrosion Defect Screening Assessment [FREE]   ±

Calculate defect screening assessment and allowable defect length from the maximum defect depth for PR-3805 RSTRENG.

The allowable defect length is based on the original ASME B31G (1999). Defects which fail the screening assessment require further assessment, or repair.

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

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 : PR-3-805 RSTRENG 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 PR-3805 RSTRENG.

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 : PR-3-805 RSTRENG Pipe Diameter From Circumference [FREE]   ±

Calculate pipe outside diameter from circumference, or pipe circumference from outside diameter for RSTRENG.

Use either the nominal pipe diameter and wall thickness, or the measured pipe diameter and wall thickness for the RSTRENG 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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