Remove ASME LPG tank? October 26, 2020, 12:16:16 pm Greetings LD-ers!2003 MB here. I've got a small leak in my ASME LP Gas tank. The leak is on threads of the plug that the gauge attaches to. I believe there is a float in the tank. The float attaches to the inside of the plug - which makes working on the plug more challenging.There is a hit on an RV forum site:how to replace propane tank float assembly - Class A - Escapees Discussion Forumthat talks about replacing the float.It sounds like the tank needs to be removed from the frame and the plug (which when the tank is mounted, is horizontal) needs to be vertical.Also, after working on the tank it seems the tank needs to be purged before filling with LP. Thus folks recommend letting professionals handle the operation.Has anyone removed or performed any repairs on their ASME tank?Thanks for any hints or help!-m
Re: Remove ASME LPG tank? Reply #1 – October 26, 2020, 01:01:07 pm Hi M; I'm sure that the fitting can be rotated a bit to tighten it up without affecting the gauge operation. I'm sure that the tank sender can be replaced through the mounting hole, and that it is far enough left of the fill ports that it won't hit anything inside the tank. So you don't need to remove the tank. Doing anything inside the tank will leave vapors inside the tank, so it needs to be emptied and purged. Dry Nitrogen would be preferred (or Argon, better) . If you have to turn the fitting too much to seal off the leak, so much that the sender quits, you can get other 'through the tank' senders. Anything more involved probably would require professional intervention. RonB 1 Likes
Re: Remove ASME LPG tank? Reply #2 – October 26, 2020, 01:23:29 pm Back in the day when repairing any type of fuel tank, I used CO2, It’s cheap, effective and readily available. If the float needs replacing, I believe the tank needs to be removed and rotated 90 degrees, to allow dropping the float assembly straight down into the tank.Larry
Re: Remove ASME LPG tank? Reply #3 – October 26, 2020, 05:13:02 pm Quote from: RonB - October 26, 2020, 01:01:07 pmHi M; I'm sure that the fitting can be rotated a bit to tighten it up without affecting the gauge operation. I'm sure that the tank sender can be replaced through the mounting hole, and that it is far enough left of the fill ports that it won't hit anything inside the tank. So you don't need to remove the tank. Doing anything inside the tank will leave vapors inside the tank, so it needs to be emptied and purged. Dry Nitrogen would be preferred (or Argon, better) . If you have to turn the fitting too much to seal off the leak, so much that the sender quits, you can get other 'through the tank' senders. Anything more involved probably would require professional intervention. RonBHey RonB,Thanks for the reply!I spoke with the local RV repair shop today and they said that regular thread compound (pipe dope) is not what one uses for LP fittings. I don't know if tightening the plug would do the trick as I believe the problem lies with the thread sealant on the plug.The RV repair shop quoted me about 4 hours to fix the leak - assuming there are no surprises, just pull the plug, apply correct thread compound, insert plug, and purge air. At $140/hr I'm still trying to decide if it is worth it.That is where I'm at right now...-m
Re: Remove ASME LPG tank? Reply #4 – October 26, 2020, 05:29:32 pm Quote from: krmugn - October 26, 2020, 04:58:50 pmI have no first hand knowledge working on RV LP tanks, so JMHO. For a simple repair, done by a professional, I would think that once the repair and tank pressure test were completed, they would add a small amount of liquid propane, or regulated LP gas to the tank, and purge through the tank outlet to clear the tank of air. Since LP gas is heavier than air, I can't imagine it would take much to push the air out.BillI wonder why the propane web sites talk about purging the air if the LP is heavier and would just force the air out. That is, not just bringing the tank to a propane fill station.Here is a quote: Caution: Do not attempt to take your new tank to a gas station or R/V dealer for the first filling and purging. from this site:Purging New Propane Tanks and Propane Cylinders - Propane Tank Store-m
Re: Remove ASME LPG tank? Reply #5 – October 26, 2020, 06:35:56 pm Quote from: Larry W - October 26, 2020, 01:23:29 pmBack in the day when repairing any type of fuel tank, I used CO2, It’s cheap, effective and readily available. If the float needs replacing, I believe the tank needs to be removed and rotated 90 degrees, to allow dropping the float assembly straight down into the tank.LarryHey Larry,Thanks for the reply!I would say you are correct about dropping the tank.Here is a quote:In the event the gauge needs to be removed from an ASME motorhome tank, the tank must dropped and removed from the vehicle. It will be necessary to remove the propane and pressure from the tank to remove the valve. Information on evacuating the propane is found in this text under ”Emptying Containers” on page 5-40. Remember that when transferring the propane to another container, the receiving container(s) must be large enough to contain the fuel. After the tank is evacuated, remove the gauge with the gauge in the vertical position. If trying to remove the gauge from the tank in its mounted position, the float will likely catch on some internal tubes and destroy the gauge assembly.The above is from:https://www.cwtechinstitute.com/wp-content/uploads/2019/09/Propane-System-2012.pdfCheers,-m
Re: Remove ASME LPG tank? Reply #6 – October 26, 2020, 06:56:15 pm I managed to delete my post while trying to edit it. ;-\I have no first hand knowledge working on RV LP tanks, so JMHO. For a simple repair, done by a professional, I would think that once the repair and tank pressure test were completed, they would add a small amount of liquid propane (edit: if the tank outlet has a regulator), or regulated LP gas to the tank, and purge (edit: at very low pressure) through the tank outlet to clear the tank of air. Since LP gas is heavier than air, I can't imagine it would take much to push the air out.Any work on the LP system should only be done by someone with a clear understanding of the significant dangers, with the proper equipment and knowledge of safe procedures, and facilities to do so!! Bill
Re: Remove ASME LPG tank? Reply #7 – October 27, 2020, 04:39:22 am I received my LD from the factory without LP gas in it. I at least thought they had closed the valve. A few weeks later when I went to get propane for the first time I noticed the valve was open. I just had it filled, moisture, air, and propane mixed. It has run fine for 20 years. RonB
Re: Remove ASME LPG tank? Reply #8 – May 21, 2021, 10:23:35 am Hello again LD-ers!Following up on this for posterity.I did end up fixing my LP leak myself. Here are the steps I performed. If anyone has questions, please reach out to me and I can provide pictures or further clarification.0. Put the LD's front tires up on ramps to gain extra clearance to remove the tank when the time comes.1. Empty all LP from the tank. Use the spit valve or turn on the burners on the range or some other way of safely/slowly emptying the tank. Depending on how much fuel is left in the LP tank this might take days or weeks.2. Turn off the shutoff valve on the tank.3. Remove the gauge from the float plug. The plastic tabs on the bottom (of the gauge) broke off my gauge from heat and age, but the gauge still seems to hold tightly to the plug even without those bottom tabs/clips.4. Pop the regulator cover off the tank. This is fastened using two plastic rivets. Remove the rivets (a wonder bar on the head of the rivet and pliers to compress the bottom).5. Break the connection between the tank and the coach. This is a copper flare fitting just to the right of the regulators. Use a wrench to stabilize the lower fitting and another wrench to break the flared nut on the top. This is pretty much regular plumbing.6. Underneath the rig, locate the ground wire ring connector attached to the tank frame. It should be close to the rear nuts attaching the tank to the chassis frame. Remove that ring connector.7. Gain access to the bolt heads that fasten the tank to the chassis. One pair of bolt heads are under the carpet in the dinette area. I (by chance) took out the dinette carpet this past December, so those heads were exposed. The other pair of bolt heads are behind the passenger seat. I removed the passenger seat for easier access to the floor behind the seat. To access these heads I made two cuts in the carpet and was able to slide the wrench in through those openings.8. Wheel a floor jack under the tank and extend the jack up until it makes contact with the bottom of the tank.9. With one person holding a wrench on the bolt heads, another person (wearing eye protection! - there is a lot of debris that falls down from the bottom side of the chassis when working on it) can crawl under the rig and use a ratchet or impact driver to remove the nuts.10. Having a person on each side of the tank (under the rig) and a third operating the jack, lower the jack to lower the tank from the rig.11. You will probably need to slide the tank off the jack to get the tank out from under the chassis. I used some cardboard on the ground to keep the tank from getting further scratched.12. Put a plastic baggie and rubber band over the coach fitting and separate bag and rubber band over the tank fitting that were disconnected in step 5. This will help keep dust, dirt, and bugs out of your gas lines.13. I ended up repainting my tank due to rust. The bottom of the tank had no paint left on it. I watched this video to get some ideas:https://www.youtube.com/watch?v=UtN1GAbCNCoI used a wire brush to clean the tank and didn't buy any fancy tape, just regular blue painters tape to cover parts of the tank I didn't want paint getting on. I ended up putting about 4 or 5 coats on the bottom of the tank. The dirt from the road really wore off the protective paint on the bottom of the tank. The gal at the paint store store said that glossy Rustoleum (or equivalent) has a harder enamel than matte Rulstoleum. The harder enamel will help resist the dirt and debris of the road.14. Make note of the position of the float plug. There should be a notch at the top of the plug. The gauge has a plastic tab that fits in this notch. Rotating the tank so the fill valve and other valves are all vertical you can now unscrew the float plug. Once the plug is freed from the threads you will need rotate the plug accordingly to get the float out.15. Apply new Teflon tape and thread compound (make sure both are LP rated - yellow packaging usually indicates gas rated.)Do all above steps in reverse order to remount your tank to the chassis.After that, I did go to a LP bulk fill station and got the tank purged and filled.A couple of interesting points from that trip:1. The LP guy said that if the tank only needs to be purged if it is exposed to air for multiple days.2. I asked about the purging process and if the LP was heavy enough to force the air out through the spit valve when filling the tank, thus not needing the purge. He said, "Yes and No". I asked if he could elaborate on his "Yes and No" answer and he responded. "Nope." So, I am still not sure if one *needs* to get their tank purged after disconnecting it and working on it.3. The purging process was pretty much fill the tank with LP vapors (not liquid IIRC) and then bleed it out. They performed this step 3 times.That pretty much finished up getting my LP leak fixed and the rig back in working order.Let me know if you have questions or comments.-m 4 Likes
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