Ivan,

I would not use use integrally welded support for this temperature that will cause large temperature gradient on the support during the operation and this may cause large internal thermal stresses at the connection to the pipe. If you can use the rod hangers as John Breen suggested you have the best solution.

In case you need to support the pipe underside I suggest you to use a clamped saddle with rotational restraints integral to the pipe.

Kind regards,

Ibrahim Demir