Hi...

I am checking some stress calculaiton of a EPC company, but they are using a lot Rx, Ry, Rz on support close to sensible equipment (mainly rotating equipments) of course, when is removed the rotationals restrictions loads over connection are exceeded... The physical support are simple trunnion with base plate and guides.... I made the comments to EPC and they insist that as the base plate are two flat surfaces in contact will not permit rotation on Rx or Rz and guides will avoid rotation Ry... I think that maybe the guides will able to avoid transfer rotation but will produce a big pressure over guides and it will produce a big friction increasing the lateral reaction.... my opinion is they are cheating on calculaitons.

Please anybody could check it and let me know the opinion.

IMHO you are correct, it's a mathematical cheat.

The real rotations that occur in a piping system are very small. Physically restraining such rotations down to zero degrees at one location is absolutely impossible, due either to unavoidable gap clearances and/or local component and structural flexibility.

Thank you MoverZ, any one have another opinion??

Dear,

I think as MoverZ said. You require an special support to avoid rotations. It is not possible with no exactly gao cero, and more being guided from a trunnion, not directly restarining the pipe. There is an inherent flexibility.

As stress calculation checker, review the support type (phisically) and how it is translated to CAESAR. Then, technically justify your criterion to EPC company.

Regards.