Too much strain on copper pipe joints?

[John Sprung]

quote:Originally posted by LazyPup

In fact, in some geologically active regions or in Hurricane regions you are required to strap the tank to the wall to prevent it falling over.

Yes, you need two approved straps, one each in the upper and lower thirds of the unit. Also, the water and gas lines to the heater must be flexible. That removes all stress on the rigid plumbing. SOP used to be brass nipples in the heater, corrugated copper flex tubes with 3/4 females on both ends, and 3/4 female NPT adapters sweated to the copper pipe. Now we use galvanized in the heater and braided stainless flex lines. That corrodes less, and is easier to work with.

The strapping requirement is because in several cases, houses survived an earthquake with minor damage only to burn to the ground because the weight of the water in the heater caused it to move and rupture the gas line.




-- J.S.

[John Sprung]

Oops -- I meant male 3/4's on the rigid pipe.



-- J.S.

[LazyPup]

Both the International Residential Code and the Uniform Plumbing Code require SDC (Seismic Design Category) strapping and flex lines in specific regions that are subject to seismic activity (earthquakes) or hurricanes, but it is not required in all locations.

in fact, in my location all Gas connections MUST BE piped the full distance and flex lines are prohibited.

When in doubt, contact your local code enforcement authority to determine what the local code requires.

[Dean]

quote:Originally posted by LazyPup

Both the International Residential Code and the Uniform Plumbing Code require SDC (Seismic Design Category) strapping and flex lines in specific regions that are subject to seismic activity (earthquakes) or hurricanes, but it is not required in all locations.

in fact, in my location all Gas connections MUST BE piped the full distance and flex lines are prohibited.

When in doubt, contact your local code enforcement authority to determine what the local code requires.

Should I reply above or below the quote ?

Anyway, good point Richard !

It's interesting to me how different factors in different areas dictate the rules.
Sometimes when I read some things posted I think to my self "that doesn't apply in my area".
As an example, you probably wouldn't find a half dozen dielectric unions on water heaters around here and 80% of the ones you do find will be very corroded and needing to be replaced after a few years.
We connect 3/4 copper directly into the tanks with a 3/4 MIP X 3/4 sweat adapter.

Experience has taught us that as long as the copper fitting is NOT female, the corrosion is much less than that of a dielectric union.
Water heaters only last 10-12 years around here so the MALE connection to the steel tank will never corrode in it's lifetime.

[LazyPup]

The requirement to use dielectric couplings between copper and iron pipe or vessels has been a code standard in all codes for over 30 years.

In this region if copper is directly coupled to the iron it will begin to corrode within 6 months and normally will leak within the first year.

It is nearly impossible to remove a copper male adapter that has corroded in place by electrolisys and normally requires replacing the entire tank.

Due to the code requirement, many water heater manufacturers are now installing dielectric fittings during manufacturing or packing them in the box with a new water heater.

In this particular city, the water company is required to check the tanks when servicing the meters or installing new service and if the dielectric fittings are not present they will not turn the water on until it is corrected.

[John Sprung]

Yes, I should have mentioned that I'm in Los Angeles. Straps and flex lines are required here. It's interesting that what's required here is actually forbidden elsewhere.

LA requires a permit and inspection to replace an existing water heater. At first that may seem overly picky, but when you think about all the different ways a water heater can hurt you -- steam explosion, gas explosion/fire, carbon monoxide, flood, falling over .... It does make sense that they'd want to check them all.






-- J.S.

[Dean]

quote:Originally posted by LazyPup

The requirement to use dielectric couplings between copper and iron pipe or vessels has been a code standard in all codes for over 30 years.

In this region if copper is directly coupled to the iron it will begin to corrode within 6 months and normally will leak within the first year.

It is nearly impossible to remove a copper male adapter that has corroded in place by electrolisys and normally requires replacing the entire tank.

Due to the code requirement, many water heater manufacturers are now installing dielectric fittings during manufacturing or packing them in the box with a new water heater.

In this particular city, the water company is required to check the tanks when servicing the meters or installing new service and if the dielectric fittings are not present they will not turn the water on until it is corrected.

No kidding, Like I said a male copper MIP fitting connected into the tank will last for years and years without any problems at all and still will be removable to use over if you wanted to do so.
We usually cut the copper and leave them in so we have a couple of tubes on top to use for handles but I have removed the old ones and used them over again many times.

Our water meters are outside and plumbers install the service lines so unless we call them to locate a curb stop for us, about all we ever see of the water company is an occasional meter reader.

The two internally lined steel nipples that come shipped in our water heaters are just "check valves" of sorts that still conduct electricity.

[LazyPup]

DEAN

The two internally lined nipples are dielectric nipples. Do not confuse electrical continuity with dielectric continuity.

Whenever two dissimilar metals are in direct contact, and the junction between the metals is reacted upon by the application of heat energy or a chemical electrolyte a very small electrical current is generated.

We see a helpful application of a dielectric current in the case of a thermocouple. A Thermocouple uses two dissimilar metals, normally nickle and copper and as it is heated in the flame of a gas pilot light it generates a current. The current is then passed through a coil of copper wire inside the gas control, which forms an electro-magnetic field to hold the gas valve open. If the pilot flame should happen to go out, the by-metal contact cools and stops generating the current, which would then stop energizing the copper electro-magnetic coil and the gas valve is closed by an internal spring. During this process electrons transfer from one metal to the other to generate the current. In time enough molecules will be transferred to physically break down the contact between the two metals which explains what happens when a thermocouple burns out.

There is another very interest property of dissimilar metal contact. While the application of heat will generate a current we can reverse the process. The external application of electrical energy to a dissimilar metal junction with either generate heat or remove heat energy from the point of contact depending upon the polarity of the applied electrical current. Thus if a battery were applied to a thermocouple the tip of the thermocouple would get warm and if the battery polarity was reversed the tip would get cold. In recent years we have seen portable ice chests for automobiles that can either heat or cool. The actual heating or cooling unit in those products is simply a large Bi-Metal plate with heat sink fins. When the automotive electrical energy is applied in one direction the plate temperature increases which then heats the container. Reversing the polarity will cause the bi-metal plate to cool, thus cooling the container.

The entire process is similar to the production of electrical energy in a dry cell battery. Voltage is the measurement of the flow of electrons from on point to another. In a dry cell battery the the electrolite is the catalist that causes the reacton. The flow of electrons is from a zinc anode to a carbon cathode. The flow of electrons continues until the zinc anode is consumed, at which point we say the battery is dead. (Properly a flashlight battery should be called a cell. A battery is a combination of two or more cells.)

In a water pipe the water serves as the electrolite, and in the case of water heaters we also have the addition of heat which further enhances the process. Electrons are drawn out of the copper and carried by the water until they are deposited on the iron. The introduction of a plastic lined nipple is sufficient to keep the two dissimilar metals separated far enough that the electrical resistance of the water is sufficient to prevent the flow of electrons from the copper to the iron in the electrolite path, thus, while the plastic lined nipples would have a direct electrical continuity, they do not have an electro-chemical continuity in the electrolytic path.

[Dean]

quote:Originally posted by LazyPup

DEAN

The two internally lined nipples are dielectric nipples. Do not confuse electrical continuity with dielectric continuity.
<snip>

Thanks Richard,

It is very confusing since the word "dielectric" means non conductor of electricity and the check valves are made of metal which would conduct electricity from the pipes to the tank.

I think I'll go look in our junk pile and see if I can get a few pictures of water heater connections that have been in for a few years.

[handytech 2004]

quote:Originally posted by austin

It is a 60 gallon electric, Super Cascade, Giant Greenfoam, hot water tank. It looks one can connect the cold water either on the top or on the side at the bottom of the tank. I don't know why it was connected to the bottom of the tank. There is also what looks like a threaded drain valve at the bottom of the tank, but I don't see how one would open it. The copper is attached to the tank with a metal elbow. It might be hardened bronze (darker than copper, rough surface, not shiny), but I don't know enough to be able to tell. In any case, it is not anywhere near 6" long. I tried twice to upload a digital picture of the installed tank, but it timed out on the last 5 kb (I'm on dial-up).