API 5L Line Pipe Wall Thickness Tolerance

Calculate line pipe diameter and pressure design wall thickness (nominal wall thickness minus corrosion allowance) from nominal wall thickness.

Some codes do not include fabrication tolerance in the wall thickness calculations (eg ASME B31.4, ASME B31.8, API RP 1111 and AS 2885). The fabrication allowance is accounted for in the design factor and is not included when calculating the pressure design thickness.

Select the pipe schedule (NPS or ISO etc), 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.

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

Calculate offshore pipeline maximum and minimum wall thickness from nominal wall thickness and tolerance (API 5L annex J table J4).

Wall thickness tolerances may be calculated from either API 5L, user defined fraction / percentage, or user defined allowance. All tolerances should be entered as positive values. Use the Result Table option to display a table of maximum and minimum wall thickness versus nominal wall thickness for the selected diameter.

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
• toltypew : Wall Thickness Tolerance Type
  • tfxu+ : User Defined Positive Wall Thickness Fraction
  • tfxu- : User Defined Negative Wall Thickness Fraction
  • tfau+ : User Defined Positive Wall Thickness Allowance
  • tfau- : User Defined Negative Wall Thickness Allowance

Tool Output

• ID : Nominal Inside Diameter
• OD : Nominal Outside Diameter
• OD/tn : Diameter Over Wall Thickness Ratio
• tfa+ : Positive Wall Thickness Allowance
• tfa- : Negative Wall Thickness Allowance
• tfx+ : Positive Wall Thickness Fraction
• tfx- : Negative Wall Thickness Fraction
• tmax : Maximum Wall Thickness
• tmin : Minimum Wall Thickness
• tn : Nominal Wall Thickness