"Fusing" a fiberglass pool return fitting

[TKR]

The return fittings that came with my pool have 2" male ends for connecting PVC fittings. However, I noticed that 1.5" PVC pipe fit loosely inside the fitting, passing through to the inside half where it fits snugly into a 1.5" female PVC connection in the flange/faceplate. I've been wondering what the internal joint is for - it does not seem like a proper alternative to the large 2" PVC fitting on the outside end. They look similar to this:

I found a video that describes using a short piece of 1.5" pipe to "fuse" the two halves of a fitting. His fitting looks just like the ones installed in my pool. After the fitting is installed, he glues a 1.5" piece of PVC pipe into the fitting, then cuts off the 1.5" pipe flush with the outside fitting before gluing on the 2" PVC supply fitting over the assembly. The purpose of this, he says, is to keep the inside flange from turning loose when a tight winterization plug (or jet) is unscrewed later.

Is this a good practice?

 

[TKR]

I did not find this type of "fusible" return fitting searching the WWW. I am going to call pool distributor today to get make/model.

After staring at this a bit, I think there may be another benefit of this. Fusing the inside flange to the outside flange with an internal piece of 1.5" pipe in this manner, looks to me like it would eliminate any possibility of return-line water pressure making its way to the silicone sealant between the fitting flanges and the pool shell.

Does anyone have an opinion on the merit of fusing the two halves together as described in the video?

 

[ajw22]

@jimmythegreek @bdavis466 you have thoughts about this fusing stuff?

 

[TKR]

(deleted duplicate post)

 

[TKR]

The pool distributor says the return fittings he installed are CMP. They are sending me 3 more so I will try to post pictures of the two halves separated

I drew two crude sketches to try and show how "fusing" this fitting may help prevent leaks when there is positive water pressure inside the return fitting.

The first pic shows the gap between the two halves when threaded together. Pressurized water could find its way through the mating threads, and to the silicone sealant between the pool wall and the flange.

_____________________

Gluing a short piece of 1.5" PVC pipe (shown green) joins the two halves and blocks of the gap.

 

[jimmythegreek]

It keeps the back on by glueing the 2 pieces together. Hes using the term fusing as glueing prevents the nut from backing out. It's fine to do but it wont stop water from coming through the front plate seal. Silicone is the standard but 3m 5200 is the material for when u dont want it to come off.....ever