Trunnion calc acc to EN13480-3 ch 11?

[DavidL]

Hi,
I want to make/understand the trunnion calculation acc to EN13480-3 ch 11. As I understand this “method” is the same as described in ASME code case N-392-3 (available here:

[link Point to another website Only the registered members can access]

[link Point to another website Only the registered members can access] One thing which is a bit worrying is the difference between FEA and these “hand calc code methods”descried in these papers. Do you use some sort of software or do you just a excel spreadsheet?

-DavidL

[mbc.engg]

Thanks

[DSB123]

DavidL,
I've just been looking at this for a Project I'm working on and all I can say is be careful if you apply this section of the Code. There are errors in the Formulae and rectangular/circular attachment formulae are intermixed by mistake. I have just sent queries on this section to the CEN which was responsible for the Code. I am awaiting responses from them.

You could get hold of FEPipe Suite which covers these types of calculations more accurately than mere hand calcs or you could develop a spreadsheet as I have done (using the correct formulae) to assess the attachments.

[DavidL]

DBS123 thanks for the info!

I have compared the formulas (only for circular attachments and full penetration weld) in EN13480 Ed 2002 (included amendments/corrections from 2006 with the ASME code case N392-3.
(CEN has updated eqn: 11.3.5.1 and 11.3.5.2 but as you mentioned I think 11.3.5.2 still is wrong should be SNT=Cw*W/AT+CN*MN/ZT+CL*ML/ZT+Q1/Am+Q2/Am+CT*MT/J ) Anyway the figure in displaying the forces and moments in ASME looks wrong to me so nothing is perfect
I will probably make the same approach as you either excel or MathCAD. I have read chapter 11 a couple of times now but have some “practical” questions concerning the moments and load cases. I use Caesar II for stress analysis. So I plan to do following:
1. Model the trunnion (with anchor + cnode) so I can get forces and moments in the center of the main pipe and local forces and moments on the “shell/surface” of the main pipe.
2. I’m a bit confused which load cases I should use:
Load case 1: Sustained case Weight+Design Pressure this will represent the moment MA. Or should only run one case with Weight to get the MA-resulting moments for sustained load ? Because I will add the pressure term in formula 11.3.7-1. Or it may just be conservative to use forces and moments from Weight and Pressure.,
Load case 2: Occasional case Weight +Design Pressure+Wind, which will represent MA+MB or did you use Weight+Wind?
Load case 3: Expansion case Weight+ Design Pressure + Max Design Temperature
Load case 4: Expansion case Weight + Design Pressure + Min Design Temp
Loadcase 5: (Exp from max temperature) =Loadcase 3-Loadcase 1, I think this will give the moments Mc (ambient to hot temp)
Loadcase 6: (Exp from min temperature)=Loadcase 4-Loadcase 1, I think this will give the moments Mc (ambient to cold temp)

How did you interpreted ML**, MN**,MT**, Q1**, Q2** and W**? The code states absolute values of maximum loads occurring simultaneously under all loading conditions. Do they mean that you should use only weight in load case 1, occasional load in load case 2, and max expansion effect from load case 5 and 6 and just summarize these absolute values for each case?
I’m a bit confused…how did you do?

-DavidL

[sumit_goel9]

can you please tell me the reference book name which have the trunion calculation according to EN13480 code.