Dear all, Dave, Richard, MoverZ, Edward and anyone else that can contribute with my cause.

First at all, I am in trouble, I work for a small company where I do not have a senior engineer who I can ask about all my doubts and we seldom do these stress analysis on Caesar, said this lets talk about the ISSUE.

We need to connect a cylindrical heater with helical coil 6 nps pipe and up fired burner [4] and, off course, we need to run a stress analysis on these new lines. I Have read some previous threads about the issue [1] [2], that is why I feel pretty worried right now, becouse of the complexity of the model.

The Vendor has given to me a draw with loads and thermal growth[3]. The easy way is just add the longitudinal displacement to the pipe nozzle and run the analysis but if you look a little bit better those fined tubes in the convectión section are not tied to anything just supported on ferrules, so the nozzle will definitelly be able to move inside the convection box regardless the thermal growth. I am just starting with this analysis but I would really appreciate if you could give me some tips, advice or guidance, I do not want to make my own refinery disaster, I am wondering if I could up load some files as soon as I run them, One more time Thanks, hope you can comment and discuss on these thread.

[1] Post 1
[2] Post 2
[3] Heater loads
[4] Heater nozzle overview

You are right to be concerned and it's good to see that posting I made several years ago illustrating the issues.

Thankfully, at least for this part, dealing with the convection section is a bit easier than the radiant model in my post that you referenced.

The convection tubs should have a couple of internal tubesheet supports inside. You'll want to get more details on the internals from the vendor.

While you have 1/8" lateral gaps (z axis in your vendor drawing) as well at a 1/8" +y gap - you can model those at the penetration point where the vendor pipe goes into the box. In reality, I expect you will see no load in the z direction (i.e. not enough deflection to engage). Depending on how you suppport your external pipe, you may see this +y support lifted off. You are given the expected thermal expansion in the X direction from the vendor.

I would model the vendor pipe as ambient - you don't care about stresses there and the expansion at the flange is given.

Model the vendor pipe into the heater shell (the vendor info should give you the wall thickness) and apply Z and Y restraints where the pipe is internally supported. There should be at least two such locations and they will form a couple. At the end on the inside, apply the 1/8" growth as an imposed displacement. I would also put an RX restraint there to represent the resistance to rotation that will exist from the U-bend to the pipe that runs back to the front of the convection box.

You should have a CNODE anchor at the flange face to check your piping load s against the given vendor allowables.

This model should give you a reasonable representation of how the heater piping will respond and generate numbers at the CNODE that can be readily checked against the allowables.

Morning Caesar users, experts and newbies like me, It has been a while since I opened this thread but I finally have the model for my ISSUE, I will upload the file just if you want to check it [1], by the way thanks to Mr Klein for his kind and helpful guidance. I have a aditional question I just hope someone can help me clarify.

1.I do not modeled The inlet (helical coil)just took the displacements by the vendor, ¿is it a Big mistake?

1. I have used a couple of supports really close (472, 471) in the outlet of the heater to keep the forces below the allowables if I use just one support the allowables are exceded, the funny thing is I have another support beside the outlet flange and this support appears to be inactive in suspension case (0 lb is carried by this one)while the 472 has to carry all the vertical load in suspension but it goes inactive in operation, Q: Does all this makes sense for you?, Is my model reliable?

2.Any comments about my file?, honestly all of them will be welcome, thanks so much for you help I am in debt.

[1]Heater Model

regards From Colombia!