ASME B31.4 Liquid Pipeline Flexibility And Stress Factor

Calculate ASME B31.4 oil and liquid pipeline yield stress and tensile stress.

Use the Result Table option to display the results for the selected stress table (API, ASME or DNV).

Tool Input

• syutype : Stress Table Type
• mattype : Material Type
  • SMYSu : User Defined Specified Minimum Yield Stress
  • SMTSu : User Defined Specified Minimum Tensile 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

Calculate ASME B31.4 oil and liquid offshore pipeline local stationary internal and external pressure from elevation.

For platform piping and the riser section above sea level the external pressure should be ignored (select the local external pressure = 0 option). Elevation is measured relative to an arbitrary datum (see figure). Mean sea level (MSL) is commonly used as a datum.

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

Tool Output

• ΔPl : Delta Pressure Across Pipe Wall
• ΔZlr : Local Elevation Relative To Reference Elevation
• Ple : External Fluid Pressure
• Pli : Internal Fluid Pressure
• wd : Water Depth

Calculate pipeline restrained and unrestrained global or external axial load and wall load from temperature and pressure for single layer pipelines.

The external pressure is assumed to be constant during installation and operation (submerged pipeline). The internal pressure is assumed to be zero during installation.

Pipeline section properties are either calculated or user defined. The axial load is calculated using the thick wall formula (API RP 1111 and DNVGL ST F101). Loads are positive in tension, and negative in compression.

The axial load can be calculated for either the nominal wall thickness, or the corroded wall thickness (nominal wall thickness minus corrosion allowance).

Tool Input

• pletype : External Pressure Type
  • Peu : User Defined External Pressure
• 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
• wtntype : Wall Thickness Type
  • tnu : User Defined Wall Thickness
• corrtype : Pipe Wall Corrosion Type
• modptype : Pipe Material Type
  • νu : User Defined Pipe Poisson's Ratio
  • αu : User Defined Pipe Thermal Expansion Coefficient
  • Eu : User Defined Pipe Elastic Modulus
• sectype : Pipe Section Properties Type
  • Asu : User Defined Steel Cross Section Area
  • EAαu : User Defined Pipe E x A x alpha
• loadtype : Axial Load Type
  • Fgu : User Defined Global Axial Load
  • Fwu : User Defined Pipe Wall Axial Load
• tc : Corrosion Allowance
• Fd : Design Factor
• Pi : Internal Pressure
• Td : Design Temperature
• Tin : Installation Temperature
• Fin : Installation Load

Tool Output

• α : Pipe Thermal Expansion Coefficient
• ν : Pipe Poisson's Ratio
• Ax : Pipe Cross Section Area
• E : Pipe Elastic Modulus
• EAα : Pipe E x A x alpha
• Fg : Global Or External Axial Load
• Fw : Pipe Wall Axial Load
• ID : Pipe Inside Diameter
• OD : Pipe Outside Diameter
• OD/tn : Pipe Diameter Over Wall Thickness Ratio
• PΔ : Pressure Difference
• Pe : External Pressure
• SMYS : Specified Minimum Yield Stress
• Sd : Allowable Stress
• Sw : Pipe Wall Axial Stress
• Sw/Sd : Axial Stress Over Allowable Stress Ratio
• t : Stress Check Wall Thickness
• tn : Pipe Nominal Wall Thickness

Calculate ASME B31.4 sction 402.5 stress intensity factors for elbows and bends. Calculate flexibility characteristic h, flexibility factor k, and stress intensification factors ii and io for pipe elbows and bends (ASME B31.4 section 402.1).

The pipe mean diameter is calculated at the mid nominal wall thickness.

Tool Input

• diamtype : Pipe Diameter Type
  • Du : User Defined Outside Diameter
  • du : User Defined Inside Diameter
• petype : External Pressure Type
  • Peu : User Defined External Pressure
• codetype : ASME B31 Code
• bendtype : Bend Radius Type
  • R/Du : User Defined Bend Radius Over Diameter Ratio
  • Ru : User Defined Bend Radius
• endtype : Flanged Or Welded Connection
• isfactype : Stress Factor Multiplier Type
  • i*u : User Defined Stress Factor Multiplier
• t : Pipe Nominal Wall Thickness
• E : Elastic Modulus
• P : Internal Pressure

Tool Output

• ΔP : Pressure Difference
• D : Pipe Outside Diameter
• D/tn : Pipe Diameter Over Wall Thickness Ratio
• Pe : External Pressure
• R : Pipe Bend Radius
• R/D : Bend Radius Over Pipe Diameter Ratio
• c : Flange Correction Factor
• d : Pipe Inside Diameter
• dm : Pipe Mid Wall Diameter
• h : Flexibility Characteristic
• i* : Stress Factor Multiplier
• ii : In Plane Stress Intensity Factor (≥ 1)
• io : Out Of Plane Stress Intensity Factor (≥ 1)
• k : Flexibility Factor
• pi : Pressure i Correction Factor
• pk : Pressure k Correction Factor
• r : Pipe Mid Wall Radius

Calculate ASME B31.4 section 402.5 stress intensity factors for compound miter bends. Calculate flexibility characteristic h, flexibility factor k, and stress intensification factors ii and io for pipe elbows and bends (ASME B31.4 section 402.1).

The pipe mean diameter is calculated at the mid nominal wall thickness.

Tool Input

• diamtype : Pipe Diameter Type
  • Du : User Defined Outside Diameter
  • du : User Defined Inside Diameter
• petype : External Pressure Type
  • Peu : User Defined External Pressure
• codetype : ASME B31 Code
• endtype : Flanged Or Welded Connection
• isfactype : Stress Factor Multiplier Type
  • i*u : User Defined Stress Factor Multiplier
• θ : Miter Bend Half Angle
• s : Miter Center Line Length
• t : Pipe Nominal Wall Thickness
• E : Elastic Modulus
• P : Internal Pressure

Tool Output

• ΔP : Pressure Difference
• D : Pipe Outside Diameter
• D/tn : Pipe Diameter Over Wall Thickness Ratio
• Pe : External Pressure
• R : Miter Radius
• c : Flange Correction Factor
• d : Pipe Inside Diameter
• dm : Pipe Mid Wall Diameter
• h : Flexibility Characteristic
• i* : Stress Factor Multiplier
• ii : In Plane Stress Intensity Factor
• io : Out Of Plane Stress Intensity Factor
• k : Flexibility Factor
• pi : Pressure i Correction Factor
• pk : Pressure k Correction Factor
• r : Pipe Mid Wall Radius
• st : Miter Transition Length (Wide Or Close Spacing)

Calculate ASME B31.4 section 402.5 stress intensity factors for extruded welding tees. Calculate flexibility characteristic h, flexibility factor k, and stress intensification factors ii and io for pipe branches, tees amd inserts (ASME B31.4 section 402.1).

The pipe mean diameter is calculated at the mid nominal wall thickness.

Tool Input

• diamtype : Header Diameter Type
  • Du : User Defined Outside Diameter
  • du : User Defined Inside Diameter
• codetype : ASME B31 Code
• loadtype : Number Of Load Cycles (ASME B31.8 Only)
• isfactype : Stress Factor Multiplier Type
  • i*u : User Defined Stress Factor Multiplier
• t : Header Nominal Wall Thickness
• Db : Branch Outside Diameter
• rc : Crotch Radius
• tc : Crotch Wall Thickness

Tool Output

• D : Header Outside Diameter
• D/tn : Header Diameter Over Wall Thickness Ratio
• d : Header Inside Diameter
• d/D : Branch To Header Diameter Ratio
• dm : Header Mid Wall Diameter
• h : Flexibility Characteristic
• i* : Stress Factor Multiplier
• ii : In Plane Stress Intensity Factor (≥ 1)
• io : Out Of Plane Stress Intensity Factor (≥ 1)
• k : Flexibility Factor
• r : Header Mid Wall Radius

Calculate ASME B31.4 section 402.5 stress intensity factors for unreinforced fabricated tees. Calculate flexibility characteristic h, flexibility factor k, and stress intensification factors ii and io for pipe branches, tees amd inserts (ASME B31.4 section 402.1).

The pipe mean diameter is calculated at the mid nominal wall thickness.

Tool Input

• diamtype : Header Diameter Type
  • Du : User Defined Outside Diameter
  • du : User Defined Inside Diameter
• codetype : ASME B31 Code
• loadtype : Number Of Load Cycles (ASME B31.8 Only)
• isfactype : Stress Factor Multiplier Type
  • i*u : User Defined Stress Factor Multiplier
• t : Header Nominal Wall Thickness
• Db : Branch Outside Diameter

Tool Output

• D : Header Outside Diameter
• D/tn : Header Diameter Over Wall Thickness Ratio
• d : Header Inside Diameter
• d/D : Branch To Header Diameter Ratio
• dm : Header Mid Wall Diameter
• h : Flexibility Characteristic
• i* : Stress Factor Multiplier
• ii : In Plane Stress Intensity Factor (≥ 1)
• io : Out Of Plane Stress Intensity Factor (≥ 1)
• k : Flexibility Factor
• r : Header Mid Wall Radius

Calculate ASME B31.4 section 402.5 stress intensity factors for tapered transitions. Calculate flexibility factor k, and stress intensification factor i for pipe welds and joints (ASME B31.4 section 402.1).

Tool Input

• codetype : ASME B31 Code
• diamtype : Pipe Diameter Type
  • Du : User Defined Outside Diameter
  • du : User Defined Inside Diameter
• isfactype : Stress Factor Multiplier Type
  • i*u : User Defined Stress Factor Multiplier
• t : Pipe Nominal Wall Thickness
• δ : Weld Offset

Tool Output

• δ/t : Average Weld Offset Over Pipe Wall Thickness Ratio
• D : Pipe Outside Diameter
• D/tn : Pipe Diameter Over Wall Thickness Ratio
• d : Pipe Inside Diameter
• i : Stress Intensity Factor
• i* : Stress Factor Multiplier
• k : Flexibility Factor

Calculate ASME B31.4 section 402.5 stress intensity factors for socket welds. Calculate flexibility factor k, and stress intensification factor i for pipe welds and joints (ASME B31.4 section 402.1).

Tool Input

• codetype : ASME B31 Code
• isfactype : Stress Factor Multiplier Type
  • i*u : User Defined Stress Factor Multiplier
• t : Pipe Nominal Wall Thickness
• C : Fillet Weld Length

Tool Output

• i : Stress Intensity Factor
• i* : Stress Factor Multiplier
• k : Flexibility Factor
• tn/C : Pipe Wall Thickness Over Fillet Weld Length Ratio

Calculate pipe spool flexibility maximum displacement check (ASME B31.1 section 119.7, ASME B31.4 section 403.9, ASME B31.4 section 403.9, and ASME B31.8 section 833.7). A formal flexibility assessment is generally not required for pipe sections with displacement less than the calculated maximum displacement. Reaction forces and moments may require separate analysis.

The developed pipe length is the length measured along the pipe center line. The difference between the developed length, and the straight line length is an approximate measure of the offsets in the line.

Tool Input

• D : Nominal Outside Diameter
• L : Developed Pipe Length Between Anchors
• U : Straight Line Length Between Anchors
• Sa : Allowable Stress
• E : Young's Modulus

Tool Output

• ymax : Maximum Total Displacement Strain

Calculate the allowable cyclic stress from the number of stress cycles (ASME B31.4 section 403.3).

The maximum value of the stress range factor is 1.2. The longitudinal stress is optional (the longitudinal stress is used to calculate the allowable stress if the longitudinal stress is less the allowable stress at maximum temperature). Sc equals 2/3 of the yield stress at the minimum temperature. Sh equals 2/3 of the yield stress at the maximum temperature.

Tool Input

• codetype : ASME B31 Code
• ffactype : Stress Range Factor Type
  • fmu : User Defined Maximum Stress Range Factor
  • fu : User Defined Stress Range Factor
• sactype : Allowable Cyclic Stress Type
• S : Design Stress
• N : Number Of Cycles

Tool Output

• Sa : Allowable Cyclic Stress
• f : Stress Range Factor
• fm : Maximum Stress Range Factor

Calculate design stress Sc and Sh from temperature for carbon steel and low alloy steel (ASME B31.4 section 403.3 and ASME B31.8 section 841.1).

Sc and Sh are used to calculate the allowable stress for cyclic loading. Sc and Sh can be calculated individually by:

`Sc = 2/3 Symin `
`Sh = 2/3 Symax `

where :

Sc = cold allowable stress at Tmin
Sh = hot allowable stress at Tmax
Symin = derated yield stress at Tmin
Symax = derated yield stress at Tmax
Tmin = minimum temperature
Tmax = maximum temperature

Refer to ASME B31.8 Table 841.1.8-1 for the temperature derating factors. 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. Use the Result Table option to display a table of design stress versus material type.

Tool Input

• syutype : Stress Schedule Type
• mattype : Material Type
  • SMYSu : User Defined SMYS Specified Minimum Yield Stress
  • SMTSu : User Defined SMTS Specified Minimum Tensile Stress
• tfactype : Temperature Factor Type
  • Tu : User Defined Temperature Derating Factor
• Td : Design Temperature

Tool Output

• S : Design Stress (Sc or Sh)
• SMTS : Specified Minimum Tensile Stress
• SMYS : Specified Minimum Yield Stress
• Su : Derated Tensile Stress
• Sy : Derated Yield Stress
• T : Temperature Derating Factor

Calculate expansion stress and allowable stress for unrestrained pipe (ASME B31.4 section 402.5). For submerged pipe use the user defined external pressure option.

Tool Input

• diamtype : Pipe Diameter Type
  • Du : User Defined Outside Diameter
  • du : User Defined Inside Diameter
• petype : External Pressure Type
  • Peu : User Defined External Pressure
• sectype : Cross Section Type
  • Zu : User Defined Pipe Z Modulus
  • Axu : User Defined Pipe Cross Section Area
• ifactype : Stress Factor Type
  • iiu : User Defined In Plane Stress Factor
  • iou : User Defined Out Of Plane Stress Factor
• M : Design Moment
• S : Design Stress
• N : Number Of Cycles
• tn : Nominal Wall Thickness
• Fx : Pipe Wall Axial Force
• P : Internal Pressure

Tool Output

• ΔP : Pressure Difference
• Ax : Pipe Cross Section Area
• D : Pipe Outside Diameter
• D/tn : Pipe Diameter Over Wall Thickness Ratio
• Pe : External Pressure
• Rm : Pipe Mid Wall Radius
• Sa : Allowable Expansion Stress
• Sb : Bending Stress
• Se : Displacement Stress
• Se/Sa : Displacement Stress Over Allowable Stress Ratio (≤ 1)
• Sl : Longitudinal Stress
• Sp : Pressure End Cap Stress
• St : Torsion Stress
• Sx : Axial Stress
• Z : Z Modulus
• d : Pipe Inside Diameter
• dm : Pipe Mid Wall Diameter
• f : Stress Range Factor
• ii : In Plane Stress factor
• io : Out Of Plane Stress factor