I have been in the same situation many times re: trunnions/trunnions on elbows, both not trusting Kellogg and lacking access to full FEA. I finally constructed a trunnion qualification spreadsheet for myself (Excel 2007 Workbook .xlsx format) based on the nuclear code (ASME Code Case N-392-3 Procedure for Evaluation of the Design of Hollow Circular Cross Section Welded Attachments on Classes 2 and 3 Piping / Section III, Div 1 Nonmandatory Appendix Y-5000) for tee-pattern run attachments. The spreadsheet includes adjustments to stress indices for elbow-mounted trunnions based on the findings of EPRI TR-107453 "Stress Indices for Elbows with Trunnion Attachments." (TR-107453 free for download here:
http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=TR-107453 )
You first construct a proper CAESAR model (see Dave's webinar). Then, using the CAESAR II output from the trunnion attachment node at the pipe wall, TRUNNION QUALIFICATION SHEET calculates whether the attachment is acceptable under Code Case N-392-3 for tee-pattern trunnions or as modified by EPRI for elbow mounting. Using weld geometry calculated per AWS, it tests whether the ovalized trunnion weld at the pipe wall will overstress and violate the pressure boundary. As Michael Fletcher said above, specific size and thickness ratios apply. I went to pains to make sure the spreadsheet is not a "black box." All the formulae are visible.
Of course, I make no warranties. My sheet is freely available here:
http://files.engineering.com/getfile.asp..._N392-3_R0.xlsxhttp://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=52480#Post52480