I know that it's not wise to connect a copper water pipe to a steel one,
without a dielectric union, or they will corrode rapidly.

However, is this also true for gas pipes?

I'm referring to a propane setup. The mobile home was previously
connected to natural gas, via black steel pipe. That pipe currently
feeds the furnace, and water heater. The water heater is going to be
replaced with an electric one, since it's old and they do not sell a
conversion kit from natural to propane gas. The furnace can be modified
by changing an orfice.

So, the black pipe will remain to the furnace and be removed where it
fed the water heater. But the house had an electric cook range, and
that needs to be changed to a propane range. Thus, the tee that
formerly fed the water heater will be used to run pipe to the range.
However, the range is further away, and it seems like it would be easier
to run soft copper tubing over to the range, since it's legal to use.
(and working with steel pipe under a trailer home is a pain in the ass,
due to the lack of space).

Anyhow, the question is whether steel pipe and copper will corrode if
connected together? I am not aware of any type of dielectric couplers
made for gas. However, the copper and steel would have a brass fitting
in between since the copper must be flared to be legal.

Anyone know anything about this?

I should mention that the underground pipe feeding the home, from the
propane tank, is copper. But there is a regulator in between, so that
should not be a problem.

On Friday, November 8, 2013 4:58:36 AM UTC-5, wrote:
I know that it's not wise to connect a copper water pipe to a steel one,

without a dielectric union, or they will corrode rapidly.



However, is this also true for gas pipes?



I'm referring to a propane setup. The mobile home was previously

connected to natural gas, via black steel pipe. That pipe currently

feeds the furnace, and water heater. The water heater is going to be

replaced with an electric one, since it's old and they do not sell a

conversion kit from natural to propane gas. The furnace can be modified

by changing an orfice.



So, the black pipe will remain to the furnace and be removed where it

fed the water heater. But the house had an electric cook range, and

that needs to be changed to a propane range. Thus, the tee that

formerly fed the water heater will be used to run pipe to the range.

However, the range is further away, and it seems like it would be easier

to run soft copper tubing over to the range, since it's legal to use.

(and working with steel pipe under a trailer home is a pain in the ass,

due to the lack of space).



Anyhow, the question is whether steel pipe and copper will corrode if

connected together? I am not aware of any type of dielectric couplers

made for gas. However, the copper and steel would have a brass fitting

in between since the copper must be flared to be legal.



Anyone know anything about this?



I should mention that the underground pipe feeding the home, from the

propane tank, is copper. But there is a regulator in between, so that

should not be a problem.

The issue with copper to steel connection in a water pipe
is that electrolysis will occur, which causes the corrosion.
Electrolysis requires an electrolyte, the water. How good of
an electrolyte it is depends on the water chemistry. With
gas, you have no electrolyte, so I don't think you have
an issue.

Even with water heaters, the place you typically find
dielectric unions, such things were never used for
50 years and the vast majority of water heaters were
replaced before the copper to steel connections leaked.
Even today you'll find that plumbers debate whether they
really cause more problems, ie leaking, than they solve.

But gas is one thing where there is a lot of variation
from what is OK in one section of the country vs another.
For example, some places say galvanized steel is OK, others
still prohibit it. So you may want to check code in
your jurisdiction.

Another option would be to use CSST instead of copper.

electric water heater will be very poor in comparison with gas.

they do sell propane water heaters.

if you go with electric go oversized tank, or be ready for cold showers.

electric will probably cost more to operate.........

has OP called the manufacturer of their existing natural gas water heater and asked if theres a Lp conversion kit? some are convertible.

the other issue is how old is the existing tank?

but i would not want a electric tank if it can be avoided

trader,

Water is a contaminent in LPG. It can and does occur throughout the
supply chain. Don't get me wrong, we're talking PPM not gallons but it's
there. Not sure how this will affect your answer.
It's easy to Google dielectric gas unions, though.

Dave M.

On Friday, November 8, 2013 7:56:28 AM UTC-5, David L. Martel wrote:
trader,



Water is a contaminent in LPG. It can and does occur throughout the

supply chain. Don't get me wrong, we're talking PPM not gallons but it's

there. Not sure how this will affect your answer.

It's easy to Google dielectric gas unions, though.



Dave M.

It takes liquid water to make an electrolyte. If you put
two different metals in a beaker of salt water and connect
them with a wire, current will flow and you can measure it.
If you just have some air with PPM water in an empty beaker,
you won't get any current or at least nothing of any
significance. It would be like a car battery with no
acid, just some acid fumes.

On Fri, 08 Nov 2013 03:58:36 -0600, wrote:

I know that it's not wise to connect a copper water pipe to a steel one,
without a dielectric union, or they will corrode rapidly.

However, is this also true for gas pipes?

I'm referring to a propane setup. The mobile home was previously
connected to natural gas, via black steel pipe. That pipe currently
feeds the furnace, and water heater. The water heater is going to be
replaced with an electric one, since it's old and they do not sell a
conversion kit from natural to propane gas. The furnace can be modified
by changing an orfice.

So, the black pipe will remain to the furnace and be removed where it
fed the water heater. But the house had an electric cook range, and
that needs to be changed to a propane range. Thus, the tee that
formerly fed the water heater will be used to run pipe to the range.
However, the range is further away, and it seems like it would be easier
to run soft copper tubing over to the range, since it's legal to use.
(and working with steel pipe under a trailer home is a pain in the ass,
due to the lack of space).

Anyhow, the question is whether steel pipe and copper will corrode if
connected together? I am not aware of any type of dielectric couplers
made for gas. However, the copper and steel would have a brass fitting
in between since the copper must be flared to be legal.

Anyone know anything about this?

I should mention that the underground pipe feeding the home, from the
propane tank, is copper. But there is a regulator in between, so that
should not be a problem.
Brass fittings are made and approved for connecting copper to iron
gas pipe.

On Friday, November 8, 2013 12:34:52 PM UTC-5, wrote:
On Fri, 08 Nov 2013 03:58:36 -0600, wrote:



I know that it's not wise to connect a copper water pipe to a steel one,

without a dielectric union, or they will corrode rapidly.



However, is this also true for gas pipes?



I'm referring to a propane setup. The mobile home was previously

connected to natural gas, via black steel pipe. That pipe currently

feeds the furnace, and water heater. The water heater is going to be

replaced with an electric one, since it's old and they do not sell a

conversion kit from natural to propane gas. The furnace can be modified

by changing an orfice.



So, the black pipe will remain to the furnace and be removed where it

fed the water heater. But the house had an electric cook range, and

that needs to be changed to a propane range. Thus, the tee that

formerly fed the water heater will be used to run pipe to the range.

However, the range is further away, and it seems like it would be easier

to run soft copper tubing over to the range, since it's legal to use.

(and working with steel pipe under a trailer home is a pain in the ass,

due to the lack of space).



Anyhow, the question is whether steel pipe and copper will corrode if

connected together? I am not aware of any type of dielectric couplers

made for gas. However, the copper and steel would have a brass fitting

in between since the copper must be flared to be legal.



Anyone know anything about this?



I should mention that the underground pipe feeding the home, from the

propane tank, is copper. But there is a regulator in between, so that

should not be a problem.

Brass fittings are made and approved for connecting copper to iron

gas pipe.

That's a good point. If you do it the normal way, you essentially
wind up with brass in between. At least all the pipe to flare
tubing fittings I've
seen, ie the common ones, are brass. Thinking about it, I've
never seen a direct steel to copper connection. But there are
plenty gas connections of copper tubing to steel pipe using the
brass fittings. Good enough for me.

No, in order to have galvanic corrosion between different metals, you need three things:

1. Different metals,
2. Those metals in electrical contact, and
3. Those metals also in contact with the same electrolyte.

What's an electrolyte?

An electrolyte is a fluid, typically a liquid, that can conduct electricity, and that's usually because it has ions in it; like salt water with it's Na+ and Cl- ions. Or battery acid, with it's H+ and SO4-- ions.

Gas cannot conduct electricity so it's not an electrolyte and there won't be any more corrosion of the piping as a result of mixing metals than there otherwise would be from different causes of corrosion.

This is why plumbers will use a brass gas shut off valve on a black iron pipe that's threaded into an aluminum gas valve. If gas were an electrolyte, that would be a house explosion waiting to happen. But, people screw black iron gas pipes into aluminum gas valves all the time without risk of explosion because gas is not an electrolyte. It's the same story for stainless steel or brass flexible connectors that fasten to aluminum gas valves.

If this were outdoors, and you had dog or drunk urinating on the junction between the iron pipe and aluminum gas valve, THEN you would have some galvanic corrosion (of the aluminum, I think), but only as long as the urine were wet and able to conduct electricity. Once it dried up, it could no longer conduct electricity and the rate of galvanic corrosion would drop to zero.

water is a contaminent in natural gas too.

espically in the summer. my best friend runs his vehicles on compressed natural gas, he has his own compressor.

he had freeze up problems and had to add a heater from the cars coolant to heat the the regulators or they would freeze up, even with a water seperator in the line

On Friday, November 8, 2013 8:37:33 AM UTC-5, wrote:
It takes liquid water to make an electrolyte. If you put

two different metals in a beaker of salt water and connect

them with a wire, current will flow and you can measure it.

If you just have some air with PPM water in an empty beaker,

you won't get any current or at least nothing of any

significance. It would be like a car battery with no

acid, just some acid fumes.

Air is an electrolyte, just a weak one compared to water.

You still get enough current to corrode. Copper is anodic so the steel will be eaten.