Sealing 110MM flexible ducting for 25mm water pipe and insulation

[mrbg07546]

Hi,

I am fitting a new water pipe and need advice how to seal the duct (110mm flexible) which contains pipe insulation and a 25mm pipe.

I heard the ducting sealant needs to waterproof and removable.

Any thoughts?

 

[Madrab]

Just use 2 of these and then 2 x 40m>25mm rubber reducers

 

[mrbg07546]

the ducting i have has a internal diameter of 97mm - would that still work?

 

[BigSnoopy01]

we talking the internal end of the run? expanding foam is used on alot of newbuild sites, or some sand and cement ontop of insulation.

 

[Madrab]

With the fins removed, probably, just use some sealant to 'glue' it in. Thin layer of sand and cement is the traditional way to seal them for sure, not too much so it can be broken to get access.
Have heard some talk about MDPE/PVC and Expanding foam reacting with each other in some circumstances, so I don't use it anywhere around plastic, that's just me tho.