IMO the micro fissures produced as the result of threading, (which I don't doubt), still only propagate as the result of user error, 'idiots using a pipe wrench to tighten barbs till they won't shift no more' is what springs to mind
. expansion~contraction under normal fitting of barbs is probably well under the critical point. I think I've only ever seen a couple of articles where there has been failure in a 'poly' top and I doubt they were Lexan as oppossed to plexiglass, the one sticks inmind featured severe discolouring/clouding as well, the bloke slapped on aload of epoxy and was satisfied with his 'fix'...
Pure conjecture I know so I'll shut up now
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