Non API Casing Strengths - Work

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API Casing strengths Worksheet, release 10, issued 30 August 2019. WORK version.

This worksheet is similar to the API casing strengths worksheet, the only difference is that the user enters pipe information rather than looking up the standard API sizes in a table. This allows the user to calculate for pipes which are not in the API tables BUT it assumes that the pipes entered are manufactured to the requirements of API 5CT.

There is no audit version of this sheet. To audit the calculations, use the API Casing Strengths Worksheet, Audit version.


This worksheet takes a set of inputs typical for tubular design. It uses the formulae defined in the referenced documents to calculate the tubing design parameters and will account for the effects of temperature, internal pressure and tension.

User input



Enter the nominal outside diameter of the pipe. L_Dcs =



Enter the nominal wall thickness of the pipe. L_tcs =



Enter the nominal weight of the pipe. wcs =



Enter the additional weight per connection. Wtconn =



Enter average joint length. Lcsav =



Enter axial force at the depth of interest (tensile is +ve). Fa =



Enter the temperature at the depth of interest. Temp =



Enter the internal pressure at the depth of interest. pi =


Enter the number part of the steel grade eg for L80, enter 80 (units are kpsi). Gr =


Enter design factor for collapse. C_dfc =


Enter design factor for burst. C_dfb =


Enter design factor for tension. C_dfts =

Click here when any values are modified to update the result.


Maximum possible pipe OD within API tolerances

Minimum possible pipe OD within API tolerances

API nominal wall thickness

Minimum possible wall thickness within API tolerances

API nominal ID

ID for minimum amount of steel used within tolerances

API Drift Dia

Nominal cross sectional area

Ratio of OD to nominal wall thickness, D/t ratio

Temperature Correction Factor

API Minimum Yield Strength, nominal, ambient

API Minimum Yield Strength, with TCF and DF

Pipe body API Minimum Burst Strength, ambient

Pipe body API Minimum Burst Strength, with TCF and DF

Pipe body axial stress at nominal CSA

API collapse resistance, ambient, no axial force

API collapse resistance with TCF, DF, Biaxial & internal pressure

Plain end pipe weight, nominal dimensions

Pipe weight average with connections, nominal dimensions

Worksheet references

API Specification 5CT, 5th Edition, April 1 1995 “Specification for Casing and Tubing (U.S. Customary Units)”.

API Bulletin 5C3, 6th Edition, October 1 1994 “Bulletin on Formulas and Calculations for Casing, Tubing, Drill Pipe, and Line Pipe Properties”, also ISO/TR10400:2007 which is expected to replace API 5C3 during 2008.

Formulae for Temperature Correction Factor taken from the Exxon Casing Design Manual.

SG of steel from taken as 7.85.

Version 1 of this worksheet released on 12 January 2009.

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