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Thread: Underground Natural Gas Pipe run

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    DIY Junior Member wujohn's Avatar
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    Default Underground Natural Gas Pipe run

    Hi,

    First - don't panic; I am hiring a pro to do this project but I want to know some unbiased opinions. I have a 3/4" stub at the back of my house and will be hooking up a natural gas fire pit. The run is probably no more than 12' and based on my conversation with an inspector it has to be buried 18" below the ground with with pea gravel or sand (cannot remember) and a tracer wire. One plumber said he did not recommend PE pipe because the run is so short and that he would run what I am guessing is epoxy coated black pipe (it could be different, I need to clarify with him) and then wrapping it in 20mil tape. The second plumber said he would recommend running the PE pipe.

    I live in San Diego so the ground in not moist except for a few months out of the year. I would also assume that having sand or gravel underneath would help drain water away from the pipe and prevent rusting. That said, I don't want to have to break up my concrete in 5-7 years to fix a rusted out pipe.

    Please give me your recommendations on what type of pipe you'd install based on the info above. Many thanks in advance.

    John

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    EDIT.

    I just saw that its only a 12' run. I would use the steel pipe. The fittings for the PE pipe will cost more than the steel. The PE pipe cant come out of the ground so you will need to use some steel anyway.......extending 18" horizontal also. Add that together on each end and you have 36" that must be steel of the 12' run. So you would end up with 9' of PE between steel pipe. makes no sense.
    Last edited by Hackney plumbing; 02-07-2012 at 07:36 PM.

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    We cant run gas pipe under a slab without using a chase open on atleast one end........in my case I would use type L copper because we cant use plastic unless its buried at least 18" deep and you cant bring it out of the ground period.

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    Plumber jimbo's Avatar
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    I assume the slab is just a patio....gas pipe cannot be buried under any part of a structure unless sleeved as mentioned by hackney.

    Steel pipe will rust out in San Diego...I have seen to much of that. The epoxy coated is better...but ANY nick in the epoxy, such as from a pipe wrench or just handling at the warehouse...is vulnerable, so I would tape the entire length. The tape is 20 mil, and code requires 40, so that is a double wrap. Make sure he uses the tape primer, or you are wasting your time with the tape. The primer is about $15 a quart, so figure $30 worth of primer, $30 worth of tape....maybe just do the whole thing in PE if he has the tools for it! We do NOT use copper for natural gas in San Diego.

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    Typically a good galvanized pipe will last 25 to 30 years in the ground here.......with the exception of were the soil and air meet. This 0-12" area will rust out in 10-15 years.

    This is unwrapped galvy pipe.....USA made. Its VERY wet here...we rival Seattle.

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    DIY Junior Member wujohn's Avatar
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    Thank you for the replies; what you say makes sense - there will be quite a bit of steel with the PE run anyway. Yes this is being run under a concrete patio, not under the home. The existing patio will have to be dug up some and I will be adding a new slab (and tying that into the existing slab) to tile over.

    Can you (or someone) please tell me what the options are for steel pipe? All I really know of is black pipe that can be coated with epoxy and/or taped. I understand there may be different coatings and one might be better than the other...

    Also, can you please explain what a chase is? I am guessing it is an opening that allows gas to escape somewhere if there is a problem with the underground pipe???

    Thanks again.
    John
    Last edited by wujohn; 02-07-2012 at 08:53 PM.

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    Quote Originally Posted by wujohn View Post
    Thank you for the replies; what you say makes sense - there will be quite a bit of steel with the PE run anyway. Can you (or someone) please tell me what the options are for steel pipe? All I really know of is black pipe that can be coated with epoxy and/or taped. I understand there may be different coatings and one might be better than the other...

    Also, can you please explain what a chase is? I am guessing it is an opening that allows gas to escape somewhere if there is a problem with the underground pipe???

    Thanks again.
    John
    We dont use black pipe here for gas outside...wrapped or not. We use galvanized outside and black iron inside buildings or galvanized.. Black iron will rust out under a house here if its not coated with somthing.
    Thats for steel pipe tho. We use copper and often a 2lb med. pressure system. We call it high pressure because its the highest pressure we can use inside a residence.

    Yes the chase pipe would allow gas to escape rather than build up into a hollow pocket under the slab waiting to be set off and go BOOM.

    ADD> I used some 3/4" pvc to run some natural gas lines underground about 25 years ago. They are still in service and have been working without issue. We painted it bright yellow!!!!!! LOL The gas company use to use polybutylene to run front yard gaslights and grills underground....with a flare connection.
    Last edited by Hackney plumbing; 02-07-2012 at 09:04 PM.

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    DIY Junior Member wujohn's Avatar
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    Thanks again. As Jimbo mentions copper is a no go here in SD so I guess it is either galvinized or epoxy coated pipe. Any other recommendations or concerns. I am from the school of trust but verify and I want to make sure what ever is done, it is done correctly.

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    Quote Originally Posted by wujohn View Post
    Thanks again. As Jimbo mentions copper is a no go here in SD so I guess it is either galvinized or epoxy coated pipe. Any other recommendations or concerns. I am from the school of trust but verify and I want to make sure what ever is done, it is done correctly.
    They may not allow galvanized in your area....Talk to the inspector and ask him what he thinks is the best. Everybody likes to tell another person what he thinks the best is. LOL

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    Moderator & Master Plumber hj's Avatar
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    Epoxy coated pipe is ONLY made with black pipe. It is about the poorest "legal" material for a gas line. I have seen it look like swiss cheese in a matter of years. Wrapping the entire run with tape would give a longer life, but any gas line under a concrete slab can get a buildup of trapped gas if the pipe leaks, and then explode when it finds a source of ignition.
    Licensed residential and commercial plumber

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    Plumber jimbo's Avatar
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    They would let you put it under the slab....but not if there was any inclination or possibility that the slab might someday become a "room"

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    Default question for HJ

    HJ,

    I was surprised at your poor review of epoxy coated pipe for gas. I always thought that was pretty sturdy. Obviously local codes would dictate but I'm curious to know your preferred material for running gas lines, both above and below ground. Thank you!

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    Quote Originally Posted by jimbo View Post
    They would let you put it under the slab....but not if there was any inclination or possibility that the slab might someday become a "room"
    We install gas lines for island cooktops under the slab on a regular basis. 4" chase pipe open on one end. Natural gas with 2lb system. Its the only way to do it.

    The material of choice here is type L copper for residential. Flare or brazed joints. 2lb systems. In the ground or in the attic.

    Systems that I have installed over 20 years ago are working perfectly.
    Last edited by Hackney plumbing; 02-08-2012 at 01:33 PM.

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    Yes i would say go with the pipe as noted above steel pipe has a tendance to rust out i have replaced a lot
    of steel gas pipe all over so. Calif, over the years,
    and i have not seen a house patio that not get a awning then being made into some type of room if not by
    you then the people you sell the house too down the road so you want to have a pipe chase, and use the pe
    pipe that will never rust out ! Even though the steel ends cost more if you ever have to replace one it would
    just be a hole in the concrete slab instead of digging up the whole thing again ! !

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    DIY Junior Member wujohn's Avatar
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    Thanks for all of the replies. In San Diego, copper is out so that leaves me with epoxy coated black pipe, HDPE, and maybe galvanized - is there something else I am missing. Since I began researching this project I had always assumed I would go with hdpe (or would it be mdpe for residential). Given the short run, my major costs (I assume) revolve around digging the trench and cutting the short run in my existing patio slab. If we are talking about $60 for epoxy blackpipe vs $200 for PE, connectors and galvanized that seems like a minimal price increase for peace of mind. Forgetting about labor, are the connectors, etc for PE pipe that expensive?

    There will nvr be a structure on the patio - not only would the HOA not allow it but it just would not work on my postage stamp of a back yard.

    Thanks,

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