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  • Under ground gas pipe.

    I am running an underground gas pipe to a spa heater with a 400,000 btu input. I'm tying in right at the meter and immediately going under ground to the heater. The length of the run is 24 feet. My trench is 18" deep and at no point does the trench go under the slab.

    I sized it at 1 1/4 inch pipe. If that is correct, what is the best material to use? Green coated steel pipe with fittings primed and wrapped or something else?

    Thanks

  • #2
    Re: Under ground gas pipe.

    Sounds like you have it figured out to me! Coated steel pipe is the most economical way to go on straight short runs, and remember to primer and wrap any nicks or gouges in the factory coating also.

    Comment


    • #3
      Re: Under ground gas pipe.

      i too would use green steel pipe. problem with hdpe is that by the time you transition from the meter to the heater, with the poly transitions, you'll have just a few feet of poly. not to mention the fusion rental or mechanical couplings.

      i like poly when i have a long trench, or one with multiple offsets. also hillsides that are difficult to dig straight and level too.

      steel pipe that's properly wrapped and primed will last a long, long time too.

      rick.
      phoebe it is

      Comment


      • #4
        Re: Under ground gas pipe.

        Around here we would use green steel. Some people use CCST as it is allowed by code here. Companies that own a fusing machine use HDPE. Im going to be working for one of those companies soon!

        Comment


        • #5
          Re: Under ground gas pipe.

          As soon as the weather cooperates, I'm going to replace a 40 foot underground section of rusted out 2-1/2 inch steel gas pipe with new
          2-1/2" Scotchcoat steel pipe. Its going to be fun cranking pipe that big together in a trench. Get to try out my new ridgid 36" and 48" aluminums!

          Comment


          • #6
            Re: Under ground gas pipe.

            coated green is home depot. Ran about 80 ft. years ago,no calls. K BOOM
            I can build anything You want , if you draw a picture of it , on the back of a big enough check .

            Comment


            • #7
              Re: Under ground gas pipe.

              I ran into a green coat (scotch coat) underground steel gas pipe system that failed in under 3 years due to special circumstances. I was told that the system was installed by landscapers so I assumed the worst when I began my leak detection. I air pressurized the gas system serving a barbeque island and gas pit. It was well over 100 feet of pipe all together. The system wouldn't hold pressure at all. 50 psi to 0 in about 20 seconds. So I filled the whole system with water and to my shock had water coming up from the pavers in several spots.

              I went ahead and dug up a section and found the specimen you see in the photos. Believe it or not the joints were very well taped with 20 mil tape. The missing scotch coating is from my pipe wrench. Check out the pitting and degradation of the coupling. The wall thickness of the pipe its extremely thin at one spot, yet thick at others and you can see where the pipe seam has given out.

              Needless to say I put in a new gas system with hdpe.

              I discovered what I believe was the cause the next day when I plugged my sawzall into an outlet under the barbeque island. When I began cutting out a piece of metal that happened to be in contact with the old steel gas pipe, sparks were flying from my blade to the metal. Best I can tell there was an open neutral at the outlet and the gas pipe was essentially serving as the neutral for the electrical circuit. I believe this caused some sort of electrolysis between the gas pipe and the earth which disintegrated the pipe in areas where it made contact with the ground over time. I found many other holes and similar damage in the old gas piping. What do you guys think?
              Attached Files

              Comment


              • #8
                Re: Under ground gas pipe.

                seen the same as your sample. had a fancy building rebuilt after the northridge quake that didn't last 4 years from the original rebuild. general contractor picked up the tab for the 11 lines that we had to replace.

                original plumber was bust and city allowed black pipe with 10 mil tape.

                holes the size of pencils. lots of landscaping had to be removed including palm trees.

                rick.
                phoebe it is

                Comment


                • #9
                  Re: Under ground gas pipe.

                  i'd buy the open neutral theory....

                  I've got a real crazy open neutral story i'll have to tell sometime.

                  The short version is that it took out all the heating controls, some lighting, and some laundry equipment.

                  Comment


                  • #10
                    Re: Under ground gas pipe.

                    Sorry! We do Elec. An open Neutral and You can not set a ground fault breaker, NO ELEC. at that outlet or ones it feeds!
                    I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                    Comment


                    • #11
                      Re: Under ground gas pipe.

                      The outlet wasn't a GFI even though it was in an exterior location. Not sure if it was fed by one though. Could be the house panel itself had a grounding issue. I befriended an employee of our local gas company and he actually checks the gas pipe before working on it to verify it isn't carrying juice. He gave me one of his little probes and told me to check it out just to be safe when working on gas.

                      Comment


                      • #12
                        Re: Under ground gas pipe.

                        Our supply house up here doesn't even stock the steel pipe primer to be used with 10 mil tape! I had to order a quart for my upcoming job. That tells me alot of the local plumbers don't bother and just wrap the joints and pipewrench scars with tape only. Not good protection that way, the pipe can rust through in those areas in just a couple of years, way faster than if the whole pipe was uncoated. I've seen it first hand many times.

                        Comment


                        • #13
                          Re: Under ground gas pipe.

                          Originally posted by plumb4life View Post
                          Our supply house up here doesn't even stock the steel pipe primer to be used with 10 mil tape! I had to order a quart for my upcoming job. That tells me alot of the local plumbers don't bother and just wrap the joints and pipewrench scars with tape only. Not good protection that way, the pipe can rust through in those areas in just a couple of years, way faster than if the whole pipe was uncoated. I've seen it first hand many times.
                          That's putting lives at risk! Terrible. You can't do enough to protect any material going underground. We always apply coppernate to all saw cuts on pressure treated lumber.
                          I, prime and over wrap with 10 or 20 mill tape. all galvey couplings. To be honest, I still worry Years later.
                          I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                          Comment


                          • #14
                            Re: Under ground gas pipe.

                            I prefer fussion pipe. To many obstructions to deal with. MDPE is a far superior material. 1" 20mil tape has worked best for me getting tight coverage on fittings and risers.

                            wookie

                            Comment


                            • #15
                              Re: Under ground gas pipe.

                              Originally posted by wookie View Post
                              I prefer fussion pipe. To many obstructions to deal with. MDPE is a far superior material. 1" 20mil tape has worked best for me getting tight coverage on fittings and risers.

                              wookie

                              Are you talking about fusion bond piping?


                              That's the piping I've used before in disagreement against the local gas company using PE piping in such a short distance. I would venture to say I had 12' underground, wrapped any part that was a fitting and literally painted the entire pipe with the black sealant that came with the tape.


                              But with the use of that pipe, an anode bag had to be installed on the piping as well. It had a copper wire that came out of the anode bag that I scratched the covering down clamped onto the piping heading into the ground.

                              Shallow ditch but couldn't go deep under the deck. I didn't want to use PE for fear of someone driving a stake into the ground and piercing it at such a shallow level.

                              The gas company advised against it but that was a code that had worked for dozens of years with exposed or underground gas piping. Given that it was fusion bond gas piping put the product superior to all the black iron that had been laid in countless main lines in the community.

                              They did however line those with PE and use the black iron as sleeves.

                              The black iron shown in this video? No way in hell would I trust that pipe knowing plastic coverings can instantly crack off. Fusion bond is some type of covering that has to be fused in a process and it has to be grinded with grinder to remove it. I've got pictures of that job somewhere on my computer, it was a hard $700 day and wasn't worth the effort. Underbid it and basically pushed a long day out of the job to make the pain go away.
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