Fibreglass resin proof seal

Silly(?) suggestion...

I've had really good results using coke bottles (or mineral water bottles for the larger sizes).

The basic premise is that coke bottles start out as a little test-tube shaped thing, and are then blown up while hot to their normal shape.

If you cut off the top and bottom of an adequate sized bottle, slip it over the pipes to be joined, and then heat with a heat gun, or really carefully with a blowtorch, the thing shrinks down just like heatshrink tubing. Add a little bead of silicone to seal, before shrinking all the way down, as otherwise you may never get the shrunk tube off to add it.

interesting trick. Do they last well in use?

NT

I've had one connecting up my pond pump to some 100mm corrugated tubing for a couple of years - the seal is watertight as far as I can tell. There is no sign at all of creep.

(Actually, in this case, the hose neatly fits into the bottle opening, and to the tubing on the other side.)

It is not a very structural fixing, though it is surprisingly strong. I most recently used this for attaching a cut-off stench pipe to a bit of hosepipe, during renovations.

So, how small a pipe wll they shrink onto? I'm wondering if they'd work for 32 or 40mm waste. Also using 2 bottles might improve strength and add a backup layer in case of damage. Or 2 halves of the one bottle, one over the other.

NT

Generally to around half the diameter or so, maybe a bit more. For that sort of size, just pick a small bottle. If you overheat it, it just melts, rather than shrinks, so be gentle.