this is more on piping design/support scope, but still i want to know some explanation for this... i don't know if there are some stress-related concerns in this kind of situation

are there any differences in selecting between trunnion with shoe or trunnion without shoe? this is in case of horizontal trunnion resting on structure

as of the moment, i always selected trunnion with shoe if i found that the trunnion length can accomodate the shoe, regardless of the supporting structure.

thanks!

Hi Zed,

When supporting high temperature lines, a trunnion with shoe would allow for sufficient temperature decay.
I am eager to know if there could be any other reasons.

Hi Zed
I do not see any reason why we need to put shoe with trunion unless there is specific requirement, Like we put trunion with shoe for some cryogenic line where we try to isolate structural member from piping & it’s attachment by micarta insulator.
In case of resting support I think there will not be any problem if we add standard shoe with trunion. stress critical point is pipe & trunion interface if that is safe then should not be any problem.

The line contact between the trunnion and the steel produces additional local stresses, see book by T.J. Vaan Laan. Adding shoes with the appropriate length or shoes with saddle on trunnions will help in reducing this loads.

If the line contact force on a trunnion is so large that local stresses are a problem in the trunnion, you use a larger diameter or thicker wall trunnion. Generally a shoe should only be needed on a horizontal trunnion if if is supported on spring with a load table, or as the guys say above.

Primarily, you would use a shoe on your horizontal dummy leg for cases where the header pipe is on shoes already. This allows all your support steel to have a common elevation (as it would in a pipe rack). If your header pipe doesn't have shoes, your dummy legs generally don't need shoes unless there is something else going on (such as a base spring, like MoverZ says.)