Check out some similar questions!

bauer09 · Jan 16, 2011, 10:43 AM

Check out these pictures -- any idea what could cause this type of corrosion? The pipe looks like it has 'craters' in it -- I tried to get an up-close picture. These gas pipes are in a basement ceiling.

I know some surface rust on black iron pipe is to be expected -- but this one seems to be a candidate for replacement... thoughts?

massplumber2008 · Jan 16, 2011, 11:41 AM

Hi Bauer09

Schedule 40 gas pipe is pretty darn thick, but that bottom picture is curious.

Take some sandcloth and clean that area that you posted. What happens when all is sanded off and washed down a bit? Let me know, OK?

Mark

PS: No danger in just sanding it... promise!

ma0641 · Jan 16, 2011, 02:17 PM

I can see from the construction features this is a pretty old house. Is this a crawl space or basement? We just had a similar situation in a 60 yr old house in Atlanta with the gas piping in the crawl. Replaced all of it.

bauer09 · Jan 16, 2011, 02:36 PM

No danger in sanding, eh? Hmm... maybe I'll bring myself to look into it tomorrow. It seems to be the only pipe in the basement that looks like this -- about a 12-foot section... I have to re-route some gas lines anyway, would be cheap insurance to replace it.

And you're right... its a 85 year old house... and it is a basement, not crawl space... dry.

ma0641 · Jan 16, 2011, 02:43 PM

At least your wiring has been upgraded! 85 years of humidity could cause this too. Black iron is pretty cheap. If doing a DIY, make sure to test for leaks.

bauer09 · Jan 16, 2011, 02:45 PM

I tested it as is with my sniffer and its OK right now... but too many news stories about homes exploding.. we just had one over in NJ last week due to natural gas.

.. and don't let the wiring you can see fool you, it's still a mess... it magically turns from romex into K&T.. so it's all coming out.

ma0641 · Jan 16, 2011, 02:53 PM

Well that explains something's. Lived in Pennsauken NJ for many years and my 1928 colonial had magic K&T to Romex too. Must be a Northeast thing. YP subfloor and wooden cross bracing gave it away. Just be careful with DIY gas piping jobs.

bauer09 · Jan 16, 2011, 05:27 PM

Thanks. Renovating is my 2nd job... Don't look forward to the times I need to deal with gas, but I try to be as cautious as possible... Gas main off, close pilots, vent pipe, pipe dope, sniff joints, fire it up & check pilots... Any other tips I'm missing?

massplumber2008 · Jan 16, 2011, 05:31 PM

I don't blame you for being hesitant for a second...

If only a 12 foot section then it is certainly simple enough to replace, but most likely, as bad as it is, you really don't NEED to replace it.

Here, in doing gas piping over 30 years, I've seen some really pitted/rusted black steel piping from outdoors and even then it was pretty much only a surface related issue as there was still plenty of thickness to the pipe where no pitting had occurred.

You said something about homes exploding. I've NEVER heard of a home that exploded because of gas piping defects. I've heard of construction accidents, digging accidents, people putting gasoline next to gas appliances and that kind of stuff, but never due to bad piping... just never happens that I know of.

Take a quick sand paper or wire brush to this and see what it looks like underneath. I'm betting all is just fine... although I have to admit that picture does look pretty bad... ;)

Let me know what you discover...

Mark

ma0641 · Jan 16, 2011, 06:29 PM

I either bubble test them or I have a gas sniffer, Northern tools $10, works pretty well

massplumber2008 · Jan 16, 2011, 07:09 PM

Any time you mess with gas piping you should take the time to test the piping with air. If leaks are found during the air test then you use a bubble soultion to help locate them.

Never skip this step... only takes a few minutes! Questions on how to do this just let me know, OK?

Mark

bauer09 · Jan 16, 2011, 07:16 PM

Good info guys, thanks a lot. I said my 2nd job is renovating... my 1st job is a chemistry teacher - I use natural gas almost everyday -- which helps my ability to work with it... it is at least not fear of the unknown... I am very familiar with the smell of the additive... and I also know what the explosive natural gas to oxygen ratio needs to be to have ignition...

I'm interested to hear about this air test... I have a very accurate combustible gas detector I've been using... it has the ability to pinpoint where the leak is coming from -- but tell me, where do you supply your air/how much psi? Do you have to shut off the valves to each appliance?

massplumber2008 · Jan 17, 2011, 06:19 AM

Hi Bauer09

No states allow for any gas detectors to be used for gas pipe testing.

Gas pipe testing an entire gas system in a house is involved in that you have to disconnect the gas meter (or can blow internal diaphragm) and disconnect the unions at all gas appliances and cap all gas lines and test through each appliance shut off. The gas test varies by state. For example, is Mass. They use a special test gauge that reads in 1/10th pound increments and we only test to 3 PSI for 15 minutes. In Other states they require a 25 PSI test for 10 minutes (use any 0-50 PSI guage). You would need to check requirements in your area. Air is fed into the system from an air compressor or even a bicycle pump (for smaller systems) and can be joined at the meter disconnection or any other place in the system. I have attached a picture showing you how to setup a gas tester... see image. I used 3/4" fittings in the example below but you could certainly use 1/2" fittings as well.

If you are only testing a branch line and can isolate that branch then you can test only the new work, but same applies in that you test through the shutoff (cap the union nipple).

This is how plumbers are required to perform tests for all gas inspections throughout the country.

I'm off to work now... chat later.

Mark

bauer09 · Jan 17, 2011, 07:31 AM

Interesting, thanks for educating me. What is the typical psi of gas coming into a home?

So when you pressurize, and you walking around searching for leaks, or are you only checking to see that the system holds the amount of pressure for the specified amount of time...

Do you set this tester up at any appliance nipple? If so, I assume you'd have to cap the connection at the meter after you disconnect that union?

Thanks again

Milo Dolezal · Jan 17, 2011, 01:07 PM

There is very little pressure in gas pipe on your side of the gas meter. However, incoming gas (from the City ) is high pressure. Not sure about how high. Gas meter has pressure regulator on its left to reduce pressure to about 0.5 psi. Also, as far as that old looking gas pipe goes: gas smells when leaking. So I would do "smell" check in your basement once every week or so. If smell of gas is detected, call Gas Co. and / or plumber. Otherwise, I would not worry too much about it.

massplumber2008 · Jan 17, 2011, 05:05 PM

Hi Milo... Nice to see you back... ;) Hey! It looks like you just told Bauer to smell for gas leaks, but we are actually talking about testing entire gas systems (or additions to gas systems) and also the awful pitting of the pipe he posted a picture of (see above). Just so Bauer is clear, I know Milo and I know he wouldn't suggest that so give him a few minutes to pop in and clarify. Otherwise, Bauer, read on...

To address your last post...

If the test holds then that is considered confirmation that the work is tight.

After connecting the meter and all the appliances back together you'd purge the air from the pipes, light the pilots (or turn on the appliances with auto. Ignition), and then you would use your gas detector to check for any leaks at the final connections.

Any appliance nipple will do as long as you cap the meter connection. Never test through the gas meter.

Finally, most residential gas is delivered at 1/2 P.S.I. (or at 2 P.S.I. and reduced to 1/2 P.S.I.), so you can see why a simple soap test or even a gas detector may fail to find a leak on occasion and why the more hardcore test really is necessary!

Mark

bauer09 · Jan 17, 2011, 06:03 PM

Great info - thanks again guys... I will certainly be adding the pressure test to my list...

Milo Dolezal · Jan 17, 2011, 06:07 PM

Thank you Mark... Now when I read entire thread, it makes lot more sense to me :D:D:D

massplumber2008 · Jan 19, 2011, 06:53 PM

Hey Bauer09...

You there, or did you explode when you sanded the gas pipe like I suggested? If you exploded... I mean, DAMN! Sorry about that :eek:

If no explosions let us know what you know...

Mark

ma0641 · Jan 20, 2011, 12:44 PM

Didn't you see CNN about the gas explosion in Phila. Yesterday that killed 1 person-Hey Bauer09 are you still there?
Brian