Again. The joints at the tank where the tails bolt on are leaking again. I've tried allsorts.

What else?

Do you have the fiber sealing washers on the fittings?

Also make sure the brazing surrounding the flanges on the pipes isn’t cracked from over-tightening

I think I used Teflon washers.

I've tried various materials and combunations. I currently have aluminiun washers in the joint. They sealed at first but now the joint is seeping.