Failing Amtrol ST 12 term expansion tank ?

I have noticed as of late my pipes have been banging toilet is making
an unusual sound and my faucets a leaking. I just checked my
water pressure it messured 140 psi. Is that to high and could it
be because the Amtrol unit has gone bad.

Thanks

You might have a bad expansion tank, but it does not cause the system pressure to become too high. The home should have a pressure reducing valve or has one that is faulty. Normal water pressure in most houses is 40-60 psi.

Toilets, dishwashers, clothes washers, and ice makers, are not designed to withstand that much pressure. In addition, your T/P on the water heater is designed to trip at 150 psi so you have no leeway on that. You need a pressure regulator valve set to somewhere around 50 psi, and a thermal expansion tank set to match the pressure the PRV setting.

The Amtrol tank may NOT be going bad, (and it has NOTHING to do with "constant" excessive pressure), but that excessive pressure is NOT good for it. You either have a failed PRV, or have a serious need to have one installed.