As much as I hate to cover up Norm Harvey's craftsmanship, I am preparing to insulate all my pipes. For the elbows and tees, I plan to use insulated PVC covers. What about this fitting (see red arrow)? Norm expands the 2" pipe from the boiler to 3" risers. What is this fitting called? Is a PVC cover available?
I would not bother covering that fitting beyond extending the straight pipe insulation down over it.
Carve out the inner wall to accommodate the fitting boss (rim) and extend the covering down to an inch above the boiler jacket. If the boiler manufacturer allows, you could probably go right to the jacket, but a nominal inch is not too much to leave exposed for clearance to combustibles.
Personally, I like to brush insulating cement (a thin white paste) over the exposed insulation ends. Makes for a much neater job.
You are right about Norm's work, Nelson. You know you have to cover it, you just hate to.
Take pictures for your album, you can share them with the boiler in it's later years, when it has grandchildren :)