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  • gas line ???

    Hi all, I want to extend to the gas pipe for the new gas stove. I have the pipe connect but not yet to the main gas line. My questions are: how do I test for leaking? If I pump 15 psi into the line, how long the pressure stay at 15 psi before it drops?

    Your help is greatly appreciate.

    Samac

  • #2
    First and foremost: Make sure your line is not attached to the stove when you put 15lbs pressure on your line to test. You will destroy the diaphram in the gas valve with 15 PSI. . The valve in your stove is rated at about 7 column inches,approx 1/2 lb.

    If you want to air test, install a plug or cap on the outlet side of your manual valve that I hope you installed just before the appliance. Make sure you cap off all other gas appliances on your system the same way or at least loosen the unions between the manual valves and the control valves on the appliances and isolate the meter. Add about 30PSI air pressure to your lines and let sit for several hours, use a gauge that you KNOW is accurate.. Take an empty spray bottle and mix a solution of dishsoap and water to where the spray from the bottle is as thick as possible while still remaining aerosal. Spray your fittings and joints first making sure to soak the entire fitting top, bottom and back. Watch each area sprayed for about a minute to see if any bubbles form. If everything appears tight wait for several hours and check your gauge, if it has not moved and you detected no leaks when you soaped your fittings then you are probably safe.

    Note: when you first spray your fittings you will see residual bubbles from the sraying, these are not caused by a leak. Watch them and if they do not grow they are not a problem. If after thouroughly soaping and air testing your system your guage shows a decline in pressure do two things. Remove the guage and check for accuracy and then soap all of the pipe you installed as well as re-soaping the fittings. It only sounds harder than it is.
    Work hard, Play hard, Sleep easy.

    Comment


    • #3
      Originally posted by samac:
      Hi all, I want to extend to the gas pipe for the new gas stove. I have the pipe connect but not yet to the main gas line. My questions are: how do I test for leaking? If I pump 15 psi into the line, how long the pressure stay at 15 psi before it drops?

      Your help is greatly appreciate.

      Samac
      Listen to Plumber. His advice is compltely right.
      the dog

      Comment


      • #4
        plumber wrote: "wait for several hours and check your gauge, if it has not moved"

        All of what plumber said is good and correct, I have a tip to add for monitoring the pressure during your drop test.

        Take a piece of tape or a post-it note and place it on the gauge face so it crosses the needle. Now draw a line on the tape or post-it at the needle's current position. when you come back a couple hours later you can easily see if the pressure has changed because the needle and your mark will no longer be aligned, and you will not have to remember what the pressure was (was it 30.5 PSI or 31.0??). As long as the gauge is reasonably accurate it should be good since we are not trying to measure a pressure, only see a relative DROP (or gain) in pressure from one point in time to another. So if the gauge reads 29 when the actual pressure applied is 30, I don't see that as a big deal for a drop test. Now if there is a minimum test pressure (and if you were to check your local code there probably is one) that must be maintained then yes you need an accurate gauge, but any gauge you are likely to buy off the shelf will not be extremely accurate, especially if it is one of the small 2, 2.5, or 3" sizes. and one that has been banging around in your toolbox for six months is sure to be out of cal.

        Most gauges are accurate to +/- 5% FS (Full Scale), even when you get into the 4.5" commerical gauges like an Ashcroft 1279SS45 which can be calibrated. To get better than 5% you are getting into Test Gauge territory and much more expensive instrumentation.

        Comment


        • #5
          If you do end up with a leak check the fittings, them self, not only the joint, I have ran across porous castings,
          Push sticks/blocks Save Fingers
          ~~~~~~~~~~~~~~~~~~~
          "The true measure of a man is how he treats someone who can do him absolutely no good."
          attributed to Samuel Johnson
          ~~~~~~~~~~~~~~~~~~~
          PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

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          • #6
            I've had a fitting with a casting hole. The contractor wanted to go cheap on materials and had me buy the overseas stuff. Said it was cheaper. I use Ward fittings in most cases. It wasn't very cheap after I had to disassemble the pipes to change out that fitting. I was paid hourly on that job.

            Comment


            • #7
              Originally posted by plumb crazy purple:
              I've had a fitting with a casting hole. The contractor wanted to go cheap on materials and had me buy the overseas stuff. Said it was cheaper. I use Ward fittings in most cases. It wasn't very cheap after I had to disassemble the pipes to change out that fitting. I was paid hourly on that job.
              I was about to say the same thing when I scrolled down and saw your post. The only time I have run into bad fittings is when they were overseas junk except for one bad Tyler soil pipe fitting which had a casting flaw.

              Comment


              • #8
                My pressure does not hold well. I lost about .1 psi in every half-hour. With this drop, it is difficult to use liquid soap mixed with water to detect the leak. Is there a better way to check for the leak?

                I run 3/4 inch pipe all the way. At one end which will go to the stove, I reduce it down to 1/2 inch before the valve. At this end, I have a 1/2 inch cap with teflon tape. At the other end, (3/4 inch) I have a gauge (bought from Home Depot) also with teflon tape to check for the pressure.

                Comment


                • #9
                  .1 PSI IS VERY MINIMAL. IT'S POSSIBLE IT IS DUE TO TEMPERATURE CHANGE. THE ONLY WAY TO TELL IS TO LET IT SIT FOR A DAY TO SEE IF THE PRESSURE CHANGES WITH THE TEMPERATURE.
                  QUESTION? ARE YOU SURE THAT IT IS .1 PSI.
                  OR IS IT 1 PSI. DON'T KNOW OF A CHEAP GAUGE THAT REGISTERS IN 1/10TH OF A POUND.
                  YOU CAN USE A THICKER MIX OF SOAP ON THE JOINTS AND FITTINGS THAT SHOULD STICK LONG ENOUGH TO SPOT. ALSO HOW LONG IS THE TOTAL RUN YOUR TESTING? IS THE LINE PROPERLY CAPPED AND VALVED OFF? IS IT A BALL VALVE? THE LONGER AND LARGER PIPE, THE MORE AIR THAT WILL HAVE TO LEAK TO REGISTER A LEAK. SORT OF LIKE FILLING A BIKE TIRE AND FILLING A TRUCK TIRE. BOTH HAVE THE SAME PIN HOLE LEAK, BUT THE TRUCK TIRE HOLDS A LARGER VOLUME OF AIR, SO IT WILL TAKE LONGER TO SHOW A LEAK.
                  HAPPY HUNTING, RICK.

                  Comment


                  • #10
                    soap should still bubble. spray the entire fitting, joint and pipe. Also spray the valves to be sure your loss is not on a packing or o-ring. spray the entire gauge to be sure it is tight. Remove the air hose and spray the valve and fitting used to pressurize your line so you know that valve is holding. (a common source for test leaks)

                    Have never liked teflon tape used alone for any type of gas piping.

                    Are there any other appliances on this line? If the answer is yes you may want to remove the unions entirely and cap or plug the valves that were leading to the appliance. Soap those valves as well. If everything is fully isolated and all of your appliances and meter are safe from high pressure, increase your test pressure to about 80psi.

                    Also test your gauge on a vessel you know to be air tight. You might simply need to return it for a different one.

                    For a leak known to be that tiny there is another way to find it but I refuse to endorse it. One thing for certain, you can't just shrug your shoulders and say, "oh well its not that big of leak".

                    There are sniffers available. You could turn your gas onto your appliance and use the sniffer. They are expensive and I know of no one who rents that equipment though your power company might come out if you told them you smell gas. This is not a recommended way to test your line but if all of your other attempts to find your leak fail it is a possible course of action.

                    I do need to ask, You are not using a tire gauge type device to test your lines are you? Can you explain the procedure you are using to add and check your pressure? For that small of a leak it could well be the way you are testing the line.
                    Work hard, Play hard, Sleep easy.

                    Comment


                    • #11
                      Rick,

                      Nice point about temperature and contraction. I had assumed he was already leaving his system on pressure for a good bit of time but if not your hypothisis <sp? could well prove true.
                      Work hard, Play hard, Sleep easy.

                      Comment


                      • #12
                        PLUMBER, YOU CUT OUT IN THE MIDDLE OF YOUR POST. HOPE YOU DIDN'T FALL ASLEEP. A SNIFFER WHICH I OWN 2 OF IS NOT SENSATIVE ENOUGH TO FIND A LEAK THAT IS POSSIBLY THIS SMALL. SOAP IS STILL THE BREAKFAST OF CHAMPIONS.
                        PS. BY THE TIME YOU READ THIS YOU'LL BE EATING YOUR WHEATIES.
                        THANKS PLUMBER.
                        RICK

                        Comment


                        • #13
                          Hi all,

                          All your previous reponses are greatly appreciated. I need more help.

                          PLUMBER RICK, Home Depot does sell the gas gauge that handle up to 15 psi and have the register of 1/10th of a psi.

                          I used soap and found two leaks: one at the gauge itself and one crack at one of the plug. I fixed the gauge and put in the new plug and still leak.

                          I temporarily used the teflon tape at both ends. Because later: One end will connect to the valve and then to the stove. The other end will connect to the union and then to the gas line. For the rest of the line, I used teflon dope.

                          The line still leaks. I suspect that I overtighted the joins and may be I crack one of the pipe. I soaps all the joins except one which is in the place that I don't want to get to. I might have to get the new pipes and redo again.

                          As I said above that I might overtighted the joins. So my question is how much torque should I apply to the joins?

                          Let's use the torque that applies to the auto wheel bolts as the reference. Should I apply the amount of torque more than the reference or less? (if you have change the tire of your car, you know what I am talking about.)

                          Samac

                          Comment


                          • #14
                            TORQUE IS FINE FOR A RUNNING THREAD SUCH AS A BOLT. ON PIPE YOU HAVE TAPERED THREADS. THEREFORE TORQUE CAN BE ENOUGH TO MAKE UP A GOOD THREAD, BUT THE SAME TORQUE MIGHT NOT MAKE UP A POOR THREAD.
                            ARE YOU CUTTING AND THREADING BY HAND? ARE THESE FACTORY THREADS, SUCH AS A NIPPLE AND FITTING. THE PROPER THREAD SHOULD ALLOW FOR 2.75 TURNS BY HAND BEFORE GETTING OUT A WRENCH. CUT TOO DEEP YOU WILL BOTTOM OUT AND NEVER TIGHTED. TOO SHALLOW AND IT WILL BE TIGHT BEFORE IT'S HALF WAY IN. ALSO DIFFICULT TO CATCH A THREAD.
                            WILL THE GAUGE GO TO 0 PSI IF LEFT FOR A PERIOD OF TIME, SUCH AS A DAY? IF YOU SOAPED EVERYTHING, THEN I WOULD DISCONNECT THAT LAST FITTING YOU SPOKE ABOUT AND CAP IT OFF. OR AT LEAST PUT IN AN APPROVED BALL VALVE. WE CAN'T USE UNIONS IN CONCEALED LOCATIONS. JUST AT AN APPLIANCE OR OUSIDE. A LEFT AND RIGHT NIPPLE AND COUPLING MIGHT BE IN ORDER. YOU BETTER HAVE GOOD THREADS IF YOU USE A L&R.
                            RICK.

                            Comment


                            • #15
                              did you use pipe dope at all the joints?or tape?dope is a much better sealant than tape and it is easyer in my opion to use just my 2 cents on the subject
                              9/11/01, never forget.

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