I am having a jacketed piping of both core and jacket of SS material,but the Operating temperature of core is 80degC and the Operating Temperature of the jacket is 210degC. This temperature Difference creates huge loads(900KN)core and jacket welding connections.

1.can we have have a bellow on the jacket pipe to absorb the differential axial expansion there by reducing the loads on the welding joints.?

2.In case of fully jacketed piping system ,whether we have to connect the elbow mid and end nodes on the core to the jacket as mentioned in the example of caesar.if yes why we are doing so.?