Ok. Very nice write up, BillA. Your claims are well backed and I completely agree that plastic tops should only be used with low durometer (soft) plastic type fittings. Contrary to a metal fitting, a plastic fitting can compress instead of excerting excessive radial expansional stresses in the block top. One more question, however: I do not completely understand why you disapprove of using teflon tape in plastic to plastic threaded NTP connections. I assume that your reasoning behind this statement is that you want to avoid increasing the outer diameter of the fitting as a whole, thereby reducing imposed radial stresses. However, have you ever noticed that good quiality teflon taped basically disintigrates when it is treaded in, filling voids while being displaced from areas of high preassure? I think this would negate the effect you are worried about.
Regarding putting each other down, we should go easy on that part. I know that there are individuals here who do have a more extensive technical background that others (namely BillA and I, for I believe that we have both had educations in the field of materials science and engineering physics). However, this does not justify to insult or put down any other party, let alone forbid them to speak. In many intelligent people, common sense is a powerful tool and I think that anyones views should be heard out as longs as there is proper reasoning behind them!
Keep it real, all
Also, this is JUST the forums, ok?