Many pipes and pipe nipples (small fittings that connect two pipes together) are made out of brass because brass is a noble metal. This means that brass does not chemically react with oxygen and cause corrosion or rusting as much as other metals, such as steel. Unfortunately, most water heater tank linings and pipes are made out of steel. If the two metals touch each other, this causes the less noble steel to corrode or rust. To prevent this, many heaters use a plastic lining in the tank, which allows the brass plumbing to touch the steel water heater tank; the plastic interior will not rust or corrode. If you have steel plumbing, you should not install a brass pipe nipple.
- If you wish to install a gate valve on your hot and cold lines above the water heater, use a steel pipe nipple with a plastic-lining.
- If you wish to install a drain pipe to the T&P valve (temperature&pressure valve screwed into the top of the tank), you need a pipe that will not freeze or rust. For this you can use a brass pipe nipple or a plastic lined pipe. You can also attach a copper flex connector with a copper pipe or you can use a galvanized pipe.
Broken Pipe Nipples
- Steel pipe nipples can sometimes break inside the threaded ports on top of a water heater. This is most likely caused by rust which makes it difficult to remove the broken nipple. If you cannot remove the nipple, place a flat screwdriver against the nipple and gently hit the handle with a hammer to bend the steel ring holding the pipe in place. Usually this will loosen the rust enough to remove the nipple. If you still cannot remove it, try cutting the steel rung with a small hacksaw blade. Be careful not to cut beyond the threads on the steel ring. It should be easier now to pry out the broken nipple
- Before installing the new pipe nipple, use a pipe tap to clean the threads on the water heater port. Then wrap the new pipe nipple with Teflon tape before inserting it. Remember that the pipe is usually just ¾ inch.
Replacing the Pipe Nipple When Installing a Combination Anode Rod
- If the water in your area is particularly hard, then it is a good idea to install a second anode rod in your water heater. If your water heater has a hex-head screw on top of the water heater, then you have one anode rod in your tank, and you can easily install a second by using a combination anode rod. (If there is no hex-head screw on top of the water heater, then your anode rod is either hidden and you can still install a second combination anode rod, or the anode rod installed in your water heater is a combination anode rod which means you cannot install a second anode rod.)
- Combination anode rods are attached underneath the hot water outlet. In order to install a combination anode rod, you will need to remove the hot water pipe nipple and replace it with the combination anode (see Anode Rods). The replacement combination anode rod’s nipple must be longer than the insulation on top of the water heater—anywhere from 2 for 6 inches.