This has been a very interesting and informative discussion
but until now nobody has answer my original question that
was the type of glue to use to glue the coil to the 2" tube.

But the question /has/ been answered -- contact the manufacturer and ask it
what the appropriate adhesive is.

You want us to give you the answer you'd like to have -- and I, for one, am
not going to do it. The manufacturer should know best.