When I was recently under my house upgrading the water lines, I noticed something pretty scary.
The gas line from the tank to the house is copper tubing. Right where it comes up into the crawl space it makes the transition to iron pipe. Whoever did the original work, failed to use a dielectric fitting, where the iron and copper meet. As a result, the iron pipe at the union is "severely" corroded. I'm glad I checked the gas line, as failure at this connection is imminent. I'll make the necessary repair in the approaching weeks. Everything under the house is iron pipe, as I'd expect, and is in good order.
Is it safe to have copper pipe running from the tank or should I dig up this line and replace it with iron pipe? I have two options, a fairly simple fix of replacing a corroded iron nipple and adding a dielectric fitting or digging up the copper line (which is in good condition) and replacing it with iron pipe. Safety is the key, the labor is a non-factor. What do the plumbing guru's say?
Well, I'm in no way a plumbing guru, but I can tell you how 99% of the propane set-ups around here are connected. Usually copper line from the tank into the house, then a flare fitting on the end of that. Connected to the iron pipe with an IP to flare fitting.
[img]/forums/images/icons/tongue.gif[/img] I'm a transplanted California native living out in the corn fields of SE Iowa, and I have to say that I was shocked to find that copper is routinely used as a carrier for propane and buried direct in the soil. [img]/forums/images/icons/shocked.gif[/img] Other than it's lack of mechanical strength, copper seems to be an ....and I say this not as an engineer, but as strictly an observer......."OK" material choice for this particular application, as I see installations that are well over fifty years old that are still "OK". Now, what I DID find that caused the hair on the back of my neck to stand up was mechanical damage to the copper tubing where it went through concrete or block walls and often shared a common bore with water and/or drain lines. [img]/forums/images/icons/frown.gif[/img] YEEK!! As we have renovated, we have plumbed the interior gas supply lines with black iron pipe. The feed from the tank, across the lawn, to the house is still copper. The copper feeder terminates at the regulator that is mounted on the side of the house. [img]/forums/images/icons/tongue.gif[/img]
[img]/forums/images/icons/tongue.gif[/img] I just had another thought about that corrosion that you saw. Suppose the stove was slightly leaking electricity to ground.......and the green grounding leg to the stove was either non-existent or was parted somewhere.......perhaps the stove....or some other gas appliance.... is actually causing the corrosion and this is a clue for you to look carefully at the power supply system??????? [img]/forums/images/icons/tongue.gif[/img]
Like Inspector507, I think copper tubing is the normal thing for LPG, but not recommended for natural gas. I'm certainly no chemist, so couldn't explain why, but I don't recall seeing any permanent LPG tanks at residential installations without the copper tubing. However, when I was doing gas leakage surveys for natural gas companies (1993 & '94), we were supposed to write up any copper tubing we found as being a hazard. Obviously codes and standards have changed over the years. In '72 and again in '77, the local gas company installed gas grills for me and both times, they tapped into the black pipe and ran copper tubing from there to the grills.
[img]/forums/images/icons/tongue.gif[/img] Thanks for the kudos, egon! [img]/forums/images/icons/tongue.gif[/img] Curiously, the codes on the west coast have historically eliminated copper as a carrier for LPG. [img]/forums/images/icons/tongue.gif[/img] The standard arrangement out in La-La Land is coated iron pipe for underground; black iron for above ground; and stainless steel "pigtails" for the appliances. The pigtail at the tank, however, is usually copper. And yes, Natural Gas does seem to have a long-term negative effect on copper; although I don't exactly recall why. [img]/forums/images/icons/tongue.gif[/img]
Natural gas lines usually have cathodic protection which may have adverse effects on the copper pipe unless the proper insulating kits are used. [ I think [img]/forums/images/icons/confused.gif[/img] ]
Thanks folks. The research I did indicates that copper is alright for LPG but not natural gas. I'll inspect the line and replace the nipple and add a dielectric fitting. The corrosion is confined to the actual threaded end of the iron nipple where it threads into the copper.
At some point in the future, I'll probably replace the copper pipe with coated iron pipe. The copper pipe could be almost 30 years old, so it's probably time to take a closer look at it and replace it.
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