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Welding black pipe (recently salvaged gas pipe)

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  • #16
    Not Recommended

    Originally posted by Bob61 View Post
    This is a request for information and safety concerns around welding salvaged black pipe from a residential renovation. It was being used to pipe natural gas from the city meter through a basement to various fixtures.

    I have an old but good AIRCO transformer welder with plenty of amps and was thinking 6010, 6011 rods.

    My idea is to cut the gas pipe into 15" lengths and weld them as rungs between 3"x2" angle to form a set of ramps that will get my car up a 16" incline needed to get it inside my shop.

    Any thoughts or suggestions would be most appreciated.
    While you may get away with this, a back of an envelope calculation says otherwise. I would not put a 4000 lb vehicle on 15" lengths of 3/4" SCH 40 black iron pipe.

    The load on each pipe will be approximate 1/4 of the total weight or 1000 lbs.
    If you, conservatively, consider the pipe to be a simple beam with a point load in the middle, the bending moment on it will be 3750 in-lbs.
    The moment of inertia of 3/4" SCH 40 pipe is 0.037 in^4.
    The bending stress on the pipe is then 53209 psi.
    The yield stress for black iron is around 35000 psi! (Please verify this.)
    Now, if you consider that the pipe is not really a simple beam and then do a more sophisticated analysis by considering the entire system, then I surmise that the stress on the pipe would be closer to 1/2 of 53209. Still, that doesn't leave much design margin.

    Lastly, keep in mind that the above calculation is for a static load. However, this ramp will have to handle a dynamic load which will be greater than a static load both vertically and longitudinally. Note that statically, the longitudinal load is very small. Dynamically, it is much larger. So beware.

    In summary, I think that in the end of the day, after a lot of work, you will have a structure that is both heavy and weak.

    Comment


    • #17
      I gave away my ramps and have no use for such. I've been wrenching on vehicles for decades.

      Instead, I use a floor jack to raise the vehicle and keep rims and 4x4s handy to support it safely. Lift with jack, toss rim under frame or appropriately reinforced unibody area, repeat.

      Ramp require wheels be installed on the vehicle so they interfere with maintenance. BTW I also worked at a used car lot shop where we pulled and stuffed many drivetrains while supporting the vehicle using the rim method. Jack stands aren't as stable as rims, which are even stable on earth or sand. We used rims in salvage yards for that reason.

      A really useful project (if you have or plan on having torches) is a cutting table. When in doubt, make equipment and make it mobile so it will be easy to take with when you move. Vise stands are handy, and vises live outdoors just fine for decades if you keep the screw greased.

      Comment


      • #18
        Actually the tread width will spread the load out well. I wouldn't hesitate to use 3/4" black pipe....especially if the legs are facing inwards on the angle leaving only a span of 9-11" depending if it's 2 or 3" angle. Just put a couple verticals along the way and you will be fine. Just be confident in your welds...Dave
        Originally posted by Arizona Joe View Post
        While you may get away with this, a back of an envelope calculation says otherwise. I would not put a 4000 lb vehicle on 15" lengths of 3/4" SCH 40 black iron pipe.

        The load on each pipe will be approximate 1/4 of the total weight or 1000 lbs.
        If you, conservatively, consider the pipe to be a simple beam with a point load in the middle, the bending moment on it will be 3750 in-lbs.
        The moment of inertia of 3/4" SCH 40 pipe is 0.037 in^4.
        The bending stress on the pipe is then 53209 psi.
        The yield stress for black iron is around 35000 psi! (Please verify this.)
        Now, if you consider that the pipe is not really a simple beam and then do a more sophisticated analysis by considering the entire system, then I surmise that the stress on the pipe would be closer to 1/2 of 53209. Still, that doesn't leave much design margin.

        Lastly, keep in mind that the above calculation is for a static load. However, this ramp will have to handle a dynamic load which will be greater than a static load both vertically and longitudinally. Note that statically, the longitudinal load is very small. Dynamically, it is much larger. So beware.

        In summary, I think that in the end of the day, after a lot of work, you will have a structure that is both heavy and weak.

        Comment


        • #19
          Originally posted by Bob61 View Post

          Thanks to everyone for the input but one thing no one has weighed in about is the last question on my second post.

          Can anyone tell me whether or not a long-used gas pipe, having contained flammable material over several decades, qualifies as a "flammable container" and is therefore risky to weld?
          Thanks again.
          If this pipe is disconnected and has been open for awhile, there should be no problem welding on it. Cut it to length and get after it. Post pix of the build and finished results.

          Comment


          • #20
            About the pipe bending, being spaced only 6" apart if a pipe started to bend the tire would then hit the pipe before, after it or both & would then stop bending. This is why I said "The worst is it will bend slightly. I don't see it failing completely to cause damage." I agree it is not ideal material to use but I don't see any harm coming from it. 3" leg vertical & 2" leg horizontal facing in.

            I would not hesitate to weld on the pipe. Even it if was flammable (which I would say it isn't but I'm not there to see it) both ends are open so it would not explode.

            Comment


            • #21
              The way you describe the ramps "to get in my shop" Im guessing you need a short "bridge" to get over a slab of concrete and in the door rather than a set of ramps to change oil and the like.

              IF that is the case, I doubt youll be happy using pipe for the ramp. Rolling your steer tires up will not be an issue but the drive tires will not work well climbing up something round. Look at car trailer ramps, nobody uses round. If that pipe gets the slightest bit damp all you will do is spin. Make it an angle instead, or even expanded metal. Give the tires something to grab a hold of.

              Comment


              • #22
                Originally posted by Bistineau View Post
                If this pipe is disconnected and has been open for awhile, there should be no problem welding on it. Cut it to length and get after it. Post pix of the build and finished results.
                Is there going to be any pics of the build when your done with it? I would like to know how they work out after you drive over them. Before and after pics maybe.

                Comment


                • #23
                  Originally posted by Bistineau View Post
                  Is there going to be any pics of the build when your done with it? I would like to know how they work out after you drive over them. Before and after pics maybe.
                  Thanks for the input. I'll let you know how they turn out and put up pics when I can.

                  Comment


                  • #24
                    Welding black pipe (recently salvaged gas pipe)

                    Do a little trial and error. Build your ramps and set them on a 4x4 (wood) on solid ground and drive said vehicles on them. If they fail then you haven't damaged your car and you can build bigger.

                    I doubt the pipe would be saturated to point of explosion. I probably wouldn't be making ramps out of said pipe but would use it for projects.

                    Weld on...

                    Comment


                    • #25
                      Just checking in to see if you started this project yet. If so, how is it turning out? Even IF it is not successful, post the results so someone else may learn about it later.

                      Comment


                      • #26
                        Originally posted by Bistineau View Post
                        Just checking in to see if you started this project yet. If so, how is it turning out? Even IF it is not successful, post the results so someone else may learn about it later.
                        Sometimes the posters get tied up in the moment and forget to respond. Not saying that about this on. But, some get 20 responses and don't even come back to their own post. Well, I guess it sometimes is hard to find time in todays world. MERRY CHRISTMAS

                        Comment


                        • #27
                          Originally posted by BD1 View Post
                          Sometimes the posters get tied up in the moment and forget to respond. Not saying that about this on. But, some get 20 responses and don't even come back to their own post. Well, I guess it sometimes is hard to find time in todays world. MERRY CHRISTMAS
                          Well he has been on here today and did not say a word on this thread. I'm thinking the black iron pipe folded when he tried to drive up on it, and now he doesn't want to admit it. Either that or he has not tried it yet. I will keep checking back to find out the out come, IF he posts it.

                          Comment


                          • #28
                            Newbie with an idea.

                            I'm new to welding and metal working but have plenty of mechanical and building experience.
                            A thought I had to spread the weight over more than one piece of pipe and also to keep the car from bumping up and down each rung is to add a piece of flat bar up the middle of the rungs. Idk, maybe 1/4 or 3/16 by 2" wide. That should spread the load and make a smoother drive up, no?

                            Comment


                            • #29
                              Originally posted by Bob61 View Post
                              Thanks for the input. I'll let you know how they turn out and put up pics when I can.
                              Is there any update on this project? I am getting curious as to whether this worked out or not. Have you even attempted to make these ramps or not? Have you scrapped the idea of making these?

                              Comment


                              • #30
                                I've been thinking the same thing. I'd like to know how it worked out.

                                Comment

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