How tight should flexi tap tails hex nuts be screwed up?

At the non tap end of the flexi tails there is a hex nut. Im fitting it to a brass fitting and I did it hand tight and it leaked. I didnt want to crush/chew the washer.

Should I have used adjustables to tighten it?

Ta.

What are you fitting it too. They do physically fit onto isolation valves and the like but they aren’t designed to seal onto the flat washer in a flexi. You can usually get away with it but not always. Depends how smooth that end face is. Ideally you fit an adaptor.  Eg https://www.screwfix.com/p/flexible-tap-adaptors-15mm-x-2-pack/2665r

Ive got it screwed to these as i had jg speedfit pipes in already from the supply.

https://www.screwfix.com/p/jg-speedfit-15mc-1-2-cylinder-connector-male/23662

They have a hex nut on them for a reason.

Its so you can use a tool to tighten them to create a seal.

👍

That’s a fair point you make. I shall go in armed. Ta.

I can’t quite understand what you’re trying to use…
Hex at the non tap end you say, you mean you have 1/2″ x 1/2″ rather than 15mm x 1/2″?

What’s wrong with these – even a plumbist can fit them without leaks!

https://www.screwfix.com/p/jg-speedfit-push-fit-flexible-tap-connector-hoses-15mm-x-x-300mm-2-pack/8349g