Trunnion spreadsheet Code Case N-392-3

If you do beam-model pipe stress analysis with Caesar, chances are good that you sometimes lack access to a full-mesh FEA program for qualifying a trunnion support in the piping design. Non-FEA options are: the Kellogg Subject 3810 method (using an online spreadsheet of questionable origin), or the BS EN 13445 or ASME Code Case N-392-3 methods which are tedious to attempt under project deadlines.

Never seeming to have the right tool for this task, I constructed a trunnion qualification spreadsheet for myself (Excel 2007 Workbook .xlsx format) based on ASME Code Case N-392-3. It includes adjustments to stress indices for elbow-mounted trunnions based on the findings of EPRI TR-107453. (Report includes Code Case N-392-3. Contrary to its original end notes, TR-107453 is free to the public with no export control restrictions.)

Too many spreadsheets online are “black boxes.” Calculations are hidden and users must take on faith the accuracy of the final output. Here, all referenced equations and intermediate calculations are shown – “Show your work,” as math teachers say. The user may inspect (but not edit) the cell functions written to calculate them. Users enter basic pipe/trunnion dimensions and material properties, plus trunnion reaction loads from pipe stress program output. TRUNNION QUALIFICATION SHEET calculates whether the trunnion attachment is acceptable under Code Case N-392-3 (for tee-pattern run attachments) or as modified by EPRI for elbow mounting. Proper construction of the stress model and load selection remain the responsibility of a trained stress analyst.

ASME, EPRI and AWS gave me permissions (on file) to reference their sections in this spreadsheet. It is offered here to colleagues at no cost, and I invite feedback on errors and code interpretation. (See spreadsheet for email address.) As with any such tool, use with caution.

TRUNNION N392-3_R0

Thanks EngineersRUs
Nice effort. Really appreciate.

Deeply appreciate the effort

sincere thanks

Thank You so much

Wowwwwwww.. very good effort..

I believe I may have found a mistake.

On rows 43 & 44 the notes state that one of the terms in the flexibility factors should be replaced with exp[-1.2 beta^3]. Whereas in your formulae for C_W it states 2.71828^-1.3905, which is not a function of beta.

Dear Dave,

Its requirement of time that CAESAR should include Trunion qualification module like flange leakage module. I understand various way of doing trunion check makes difficult choose most widely accepted method to analyse,but Its very essential to reduce time when file consist number of trunion, i know its possible with not much programming effort.


Next version of CAESAR should include this tool to ease external calculation time.

Thanks..

Yes it is really required to include this module in Caesar as trunnion calculation is mandatory part of stress analysis and is required significant time to check trunnion stress by other means.

CAESAR II does include a module to check trunnion attachments on elbows.
A webinar on this subject was broadcasted this year.

www.vannella.com

A combination of 1) the fact that the results of this module are vastly conservative compared to FEA solutions in most cases, and 2) limitations of applicability on pipe sizes versus thicknesses narrows the usefulness of this tool greatly.