I installed a new electric 50 gal Richmond water heater over the weekend. The new heater had installed already these blue plastic lined nipples on both the hot and cold. I pre-sweated copper female adapters to the copper pipe and then attached the female adapters to the male nipples. After doing such, I've read that there could be a problem with corrosion taking copper directly to the steel nipple. I did not use dielectric fittings because these corroded so badly in my last water heater....(I had to change them mid-way through the life span of the previous heater). We have extremely hard water here in Indianapolis and I don't have a softener. So, getting to the question...Am I OK as is because the nipples were plastic lined or should I replace with other fittings? Any help anyone could provide would be greatly appreciated!