The failed pad in the picture is the worst I have come accross. As I mentioned on hot especially creep range lines any attachment weld, pad and similar tend to fail at the end. It is only a question of time. Unfortunately I was not on site when the failure happened so no close up inspection.
- small pad yes
- bad welding yes
- pad was insulated but it is possibly different material to pipe and in addition is cooler than pipe
- bracket is correct size. Pad should not be there at all. Trick for this design is inside the pipe.

This type of bracket without the pad will fail also if temperature is higher. It will actualy fail even if there is no external force. Very high temp designs have floating rings with shear lugs for this reason. Basically same design as raiser clamp.

You weld a trunion on main steam line on utility boiler without attaching anything to it and after 20 years there is a crack. We have found cracks even in gamma bosses. (Plugged and reinforced small hole to get radioactive source inside the pipe)

Easier and safer to use raiser clamps. No FEA, no problems in getting special pipe, minimal welding and minimal failures. I just checked 22 year old 800NB steam line which had really bad hammer. No damages what so ever on clamp supports with lugs. Next project is P91 MS line where somebody put trunions only on one side of a vertical pipe. Will be expensive for the plant owner to fix them.

Cold lines are different.