28-03-2022, 08:03 PM
Annealing the pipe is a good idea, it removes stress in the joint improving the ability to seal and also reduces the tendency for copper to crack as it work hardens over the years. Fibre washers relax under compression in my experience and need checking a couple of times when a joint has been newly made, once they have settled in you should have no more problems. Graham I suggest that you had another issue that compounded your problem and which prevented you from gaining a leak free joint, such as damaged faces old hard washers, stretched raised thread, or some other issue. All that said a light smear with a petrol resistant sealant is a good idea if all else fails even though I have rarely ever found the need to do so.
Black Art Enthusiast