Advice on gas pipes showing some rust...


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Old 10-19-10, 09:53 AM
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Advice on gas pipes showing some rust...

I was under the house the past weekend putting down some vapor barrier and noticed
two sections of gas piping that had collected some rust. Is this "normal", or is it something
that needs to be replaced? This runs from the gas meter outside, through the crawl space, and
up into the garage (to a gas water heater).

Here are some pics to show what I'm talking about:

PIPES pictures by hikerguy1 - Photobucket

Thanks,

Andy
 
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Old 10-19-10, 10:42 AM
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Advice

Hello,

No, the rust you posted about is only surface rust and all Gas pipes will do that. Very common. Those pipes are made from Black iron,and they will still be here after we are gone!



LaserBeam
 
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Old 10-19-10, 11:34 AM
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While I don't disagree with LaserBeam I suggest that you wire brush the loose rust and then paint the steel piping with Rustoleum primer and a Rustoleum top coat.

Also, it would be best if that pressure regulator had the vent piped outside.
 
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Old 10-19-10, 12:09 PM
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Thanks Laserbeam. That's a relief.

Furd, I think I'll take the steps you recommend as well. I'm not clear on
the vent pipe you're talking about. Which picture shows the vent pipe?

Thanks,

Andy
 
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Old 10-19-10, 03:24 PM
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Picture three, the brass "plug" on the top of the regulator on the right-hand side is the vent. That plug should unscrew and then you can add the vent piping to run outside. The reason for the vent is two-fold, it allows atmospheric pressure to work on the side of the diaphragm away from the gas and it also acts as a relief vent in case the diaphragm ruptures. Piping the vent outside would prevent any gas build up in the crawlspace should the diaphragm rupture.

Diaphragm ruptures are not common but they do happen.
 
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Old 10-19-10, 03:47 PM
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Furd, if I'm looking at this correctly, the regulator is the silver object (the only part that's NOT rusted Correct? And the small part that's barely visible to the right most side of this part is the vent, correct?

I think I'll give my gas company a call and see what they recommend. It makes sense what you're saying. My guess is it wasn't required by code, and if it wasn't required, then why would someone spend time on it when they're installing it. Builders always go the cheap route.

Also, is it common to have what appears to be two regulators for a pipe run like this? Picture 1 and 2 shows the first one (nearest the gas company's meter outside), and pcis 3 and 4 are show the other one.

Thanks,

Andy
 
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Old 10-19-10, 06:20 PM
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Two regulators? No, that is not common although I can think of one reason why you might have two. Generally there is a regulator on the inlet side of the gas meter and then you might have a regulator at an appliance but more often the appliance will have the regulator built-in to the automatic gas valve such as the furnace or water heater valve.

Was your home originally serviced with propane and later connected to a natural gas main?

The pictures look to be all of one regulator, albeit from different angles. Maybe that's because they are fairly close pictures. I took one of the pictures and added some captions.

 
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Old 10-19-10, 08:01 PM
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Usually the utility supplies a regulator at the gas meter. Part of the regulator has an overpressure relief valve that vents gas if the gas company's distribution system is over-pressurized.

Some utilities provide gas pressure at 2 PSI from the regulator. These systems require an additional regulator at each appliance to cut the pressure down to the more common level for appliances of about 1/4 PSI.

So that regulator could be a regulator on a two pound system. More likely it's an appliance regulator cutting the pressure again from 1/4 PSI to about 1/8 PSI (from about 7 inches water column to about 3 inches water column, the pressure used at the burner manifold of most natural gas appliances.

The pressure should be specified on the regulator.
 
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Old 10-19-10, 08:07 PM
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Personally I'm with laserbeam. Bare steel ("black iron" ) piping that is outdoors and exposed to the weather might do with priming and painting.

But even such pipe rarely corrodes enough to be a hazard --- not unless some dog pees on it regularly.

The gas utility I worked for did require that it's black iron pipe on meter sets outdoors be primed and painted. No harm on doing that for outdoor pipe on the customer's side of the meter.

But I wouldn't bother doing it inside unless there were conditions that caused drips or high humidity on the pipe.

The picture shows pipe that has more rust than I'd usually expect indoors, but no deep pitting that might be a worry. Surface rust I wouldn't be inclined to worry about.
 
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Old 10-20-10, 06:48 AM
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Furd, the pics might be a bit confusing (they do look similar). There are definitely two regulators. One is maybe 5' from the gas meter, and the other one maybe 10' from the first one. We're the third owner, but I'd guess it was always natural gas. I see no signs of an external propane tank. Thanks for clarifying the vent. That's what I thought you were talking about.

SeattlePioneer, thanks for the additional info. The second regulator is probably 20' from the water heater, so it's probably kicking the pressure down as you noted. I don't think the humidity gets that high under the house (we live in N. Carolina). I didn't notice any deep pitting. Looked like surface rust. I'll take a peak again just to be sure.

Thanks,

Andy
 
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Old 10-20-10, 10:37 AM
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The pressure the regulator provides downstream ought to be listed on both regulators. If you can find that information it would likely help determine the purpose of the regulators.

The utility I worked for marked two PSI piping systems with tape to help identify that kind of system. That's probably pretty rare in homes, so very likely the utility is supply gas at 1/4 PSI or so --- 7"-8" water column or thereabouts.
 
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Old 11-29-10, 01:51 PM
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I ended up calling my local gas supplier (PSNC Energy) just for peace of mind. He basically said what everyone else has said on this forum. The guy took one look at it and said "that's not a problem. It's just surface rust. You have absolutely nothing to worry about." He said he's been in the business for 25 years, so I guess he knows what he's talking about. He also said he wouldn't worry about piping the vent outside. Just thought I'd pass this info along.

Thanks for all who posted.

Andy
 
 

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