Dear all,

Why the tower 1st support shall be trunnion with anchor. any reason behind the support and location. if any calculation required please guide me. refer the attachment for easy understanding

It is a rest support. Sometimes there are guides also.

What else do you think will be suitable in your opinion? If you put the support that you think will be adequate for the job, we can discuss on it.

The trunnion support in the picture gives the pipe ability to rotate, which is very likely, at support, and takes the load vertically. Do you think the large resultant bending moment can be taken by the nozzle if the pipe can not rotate at support ? You can check this in the stress analysis easily, don't you?

As long as the nozzle is capable to take the axial forces and bending moments under seismic/wind effect there is no need to use additional guide at support location, the trunnions are sufficient.

Ibrahim Demir

Any Calculation or criteria is for to fix the first support?....One of the client have some criteria but they didnt not sure....can you guide me plz...

If it's an overhead line off the top nozzle, usually the support will be close to the tan line.

If as shown in your picture, a nozzle off the vessel side, the support should be as close to the nozzle elevation as possible.

The loads in the support are obvious. The associated vessel wall and support steelwork calcs are simple.

Shaber,

You give a picture only, nothing else. How about the temperature profile in the vessel and the temperature in the pipe? Wind loading, seismic load requirements?
Have you modelled and provided a pipe stress analysis?

In case there is no thermal load in both vessel and pipe you can anchor the pipe on the support. I guess the sustain loads can be taken by the nozzle and the anchor.

I guess there is a disagreemnt in the terminologies between your client and yourself. I know that there are some companies calling the line stoppers as anchor or fix support by considering the direction only. Yours might be the same. The directional anchor or directional fix support (in line with pipe longitudinal direction) in your case is the trunnion support

If the terminology does not cause the disagreement, you need to give your calculations to the client with trunnion support and anchor support, they can make the decision themselves.

I hope your client is not your boss.

Ibrahim Demir

Hai Ibrahim and Mover z,

Thanks for your information...

vessel diameter is 2182 OD and length is 25m, wind speed is 32m/sec, seismic load shall be in Gx1 =.11g's, Gy2 =0.39g's, Gz3=.28g's and material SA 240 ss316


what calculation we have to submit? As per stress analysis, we fix the 1st support and nozzle load are within allowable.

Could please provide calculation sheet for the above conditions.

why we have to use the 1st support as trunnion type?

Shabeer,
You asked: Why do we use a trunnion type pipe support as the primary support for lines on tall vertical vessels?

I would ask, if you do not use a Trunnion type support for this application what would you use?

Hai jop,

we provide the clips and use support as clamp type.

based on the client comment we go with trunnion type, i dont know the reason, why we go with primary support as trunnion type. could you guide me, if your are aware of the calculation and reason behind the supports.

Shabeer,

Do your piping stress analysis and nozzles pass with the type of the support in your mind?

When you change the support type to trunnion type do you see any improvement in the sipe stresses, nozzle and support loading?

If the second gives improvement into the piping system by reducing stresses, nozzle and support loads and if you do not have any problem with the natural frequency of the piping why do not use the second option without the client input?

I guess I gave the reason in my first comment above to your question.

Ibrahim Demir

Dear Shabeer,

Generally First support is rest... Trunnions for vertical lines...

are your client asking about Local stress calculation for Trunnions to check for Axial load, Longitudinal load and circumferential load?

Also how clamp type support you are using, will take the whole vertical load?

From what I see in the picture:

Since you haven't provided the temperature, my comment here is just case you have thermal expansion in your sysem. For sure you need to remove the vertical load from the nozzle, for that in case the position of secondary support is in much lower elevation, then longer length vertical riser would create a large bending moment and sheer load on nozzle due to thermal expansion. so a primary support like trunnion make it possible to minimise this length as well as taking vertical load by hanging the lower portion of riser, however in bottom section that's not shown in the photo enough room shall be provided for sagging. To make sure the local stress generated at your trunnion is within the limits I suggest to use Kellogg method.