Please let me know if somebody has done HDPE pipe stress analysis using Caesar II?.Please share your experience.

I would not use CAESAR II or any similar software for plastic pipe. Some plastic pipe suppliers give excellent design manuals. One of those is Austrian (Not Autralian) company AGRU. You can download their technical literature.

Jouko

What support are normally used to support Long Risers (vertical runs) of HDPE pipes? I have experience using adhesive-collars on GRE lines usually to support long vertical runs. Is a smilar concept used ?

Sorry, I cannot answer this one.

Maybe you can ask to Sir Bom because he is our advicer and young consultant in pipe stress analyst in our company. He is a part of our big on going project which is like yours HDPE, but unfortunately I belong to other project as a pipe stress analyst too.