Propane gas line

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Propane gas line

Postby Shadow Catcher » Thu Dec 08, 2011 8:01 am

Now that I have the Bullfinch gas point I am bumping up against the gas line. One of the problems with Compass Rose is the gas line from the front of the trailer. They followed the RVIA standard and used black steel line under the trailer. Unfortunately it was a half assed job, There is a drop that sticks three or four inches below the axle, it is the lowest point of the trailer and just waiting for a rock to come along and do a lot of damage. On top of this it provides a place for water to accumulate. It gets worse, from there as they used copper line up through the floor and the hole is not sealed and the copper is kinked/crimped where they tried to bend it with out using a spring or tubing bender.
RVIA standards or not the black steel is as far as I am concerned a goner, and that leaves two choices polyethylene (the yellow pipe used by utilities) or copper. Polyethylene seems to be A, difficult to install and B, only UV stabilized for three to five years so I guess this means copper.
I am suspecting that RVIA standards call for black steel because of home standards. Sulfur in natural gas will cause the inside of conventional copper to flake.
I have not worked with copper before other than to test for leaks so I am looking for insight :thinking:
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Postby bobhenry » Thu Dec 08, 2011 8:37 am

Tommy is there anything stopping you from taking the black pipe up and over the axle rather than down and under?

I have permanently fixed gas only on the chuckwagon and this was my first experience with running a dedicated gas line in my 4 builds. I treated mine just like a house line it run the length of the trailer hugging the floor to just inside the galley where with a 90 fitting it pops thru the floor and a standard gas line compressionfitting was installed then a standard flex line was ran from there to the stove, just like in my home. I came from the chemical industry and did a million miles of plumbing in iron pipe. copper. PVC. CPVC. kynar. (an exotic plastic) and yes even glass. With road debris and the concerns you have voiced I would be most trusting of black pipe properly installed and secured. While I have seen your 1st trailer I am not familiar with what you may be up against with your new one but surely there is a way to redesign and salvage the black pipe with some intelligent redesigning.

Just my 2 cents worth !
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Postby bdosborn » Thu Dec 08, 2011 8:59 am

I used gas rated copper on my trailer without any issues. It's harder to work with than you would think as it work hardens when you bend it. I tucked all my piping behind the frame to protect it. I used flare fittings which are harder to work with than compression. Every commercial trailer I've looked under used copper piping at some point to transition from black pipe.

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Postby Shadow Catcher » Thu Dec 08, 2011 6:04 pm

Bob there is maybe a 1/4 inch between the axle and a frame cross member. A picture is worth...

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I will go for the copper and protect it, and Bob I am familiar with the flare fittings but do not have a flare tool large enough, or maybe I do.
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Postby Cdash » Thu Dec 08, 2011 7:25 pm

I would suggest drilling a hole in that cross member above the axle and route it up through there - problem solved! You could even offset it and use all the fittings that are already there. Would just need to apply new dope to the threads.

Just an idea......
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Postby Shadow Catcher » Thu Dec 08, 2011 8:27 pm

I am extremely reluctant to drill a hole in a major structural element, particularly as big as this would be.
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Postby eamarquardt » Thu Dec 08, 2011 8:42 pm

You might consider using "marine" grade hose. Propane on a boat is a much more serious thing than propane on the underside of a trailer. Boats typically have no holes in the bottom for leaked propane to escape from so the propane pools and goes boom at a most inconvenient time (like miles from the nearest shore). Soooo, IMHO, if it's good enough for a boat, it's good enough for a trailer if proper anti chaffing steps are employed.

http://www.pridemarine.com/index.cfm?ca ... 9749000167

Re drilling through a cross member. It looks like your cross members are aluminum tubing. Most of the strength comes from the top and bottom surfaces not the vertical surfaces connecting the two together. Look at ribs/frames for aircraft structures. Very little material in the center of the rib/frame as the flanges are the important part. All the material in the center does is connect/hold the flanges in place. I wouldn't be concerned with drilling a hole big enough for the propane line and some chafe material. If you provide me with the specs for your frame I can have #1 son, with the $100K ME degree that I paid for, run some calculations to tell you how little you've effected the strength of the beam. Also, the closer you drill to the outside of the frame the less it will matter as the stress there is less than in the center of the beam.

Another approach might be to put a shim between the axle and frame (if possible) to give you more clearance between the two and route the pipe through there. It would change the height of your trailer a little bit but might be a viable option.

I agree that the iron pipe was done haphazardly.

There you have it: "More World According to Gus".

Hope this helps.

Cheers,

Gus
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Postby bdosborn » Fri Dec 09, 2011 9:47 pm

eamarquardt wrote: If you provide me with the specs for your frame I can have #1 son, with the $100K ME degree that I paid for, run some calculations to tell you how little you've effected the strength of the beam.


I'd be interested in seeing that. Intuitively I would guess that a hole in the side would weaken it more than the top but I didn't spend that much on my degree. :lol:

Bruce

P.S. Why not replace just the portion of pipe below the axle with flexible tubing?

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Postby Treeview » Fri Dec 09, 2011 11:00 pm

If strength loss is critical there are ways of running the gas line through the aluminum.

Find a piece/sleeve of aluminum tubing with an ID larger than the black iron. Drill a hole in the frame tubing the same as the OD of the sleeve. Have the sleeve welded into place. Leave a generous air gap between the al and black iron so they don't rub. Secure the black iron with hangers to allow fore/aft movement but not vertical.

Whoever did the original installation must have not gotten ANY education! That is terrible work!

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Postby Corwin C » Fri Dec 09, 2011 11:23 pm

bdosborn wrote:
eamarquardt wrote: If you provide me with the specs for your frame I can have #1 son, with the $100K ME degree that I paid for, run some calculations to tell you how little you've effected the strength of the beam.


I'd be interested in seeing that. Intuitively I would guess that a hole in the side would weaken it more than the top but I didn't spend that much on my degree. :lol:

Bruce

P.S. Why not replace just the portion of pipe below the axle with flexible tubing?


Actually the center (vertically) of the frame member will have the smallest loads. If that member is holding up the floor, the top is under compression and the bottom is under tension. The center has very little force applied to it at all. This is why an "I" beam works so well. The center web actually carries very little load.

I wouldn't be happy with that setup either. It's hard to tell from the picture. It appears that the frame components are a 3" box beam or even 3" channel stock. Drilling a 1" or even a 1 1/2" hole wouldn't weaken the structure significantly if it was done properly. If it's angle stock, I'd move it toward the corner of the "L" a little from center. If all that member is holding is the floor, I wouldn't have any issues whatsoever drilling a hole if it was mine. If you go with copper, it looks like a 3/4" hole would be large enough. Don't forget to protect them from touching. Dissimilar metals are a magnet for corrosion issues.
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Postby Shadow Catcher » Sat Dec 10, 2011 7:58 am

Gus, the frame is 3.00 X 1.5 X .110" actual measurement. I kind of like the aluminum sleeve idea as the frame is more or less sealed so leaks are a concern inside the frame.
I picked up the 15 MM Whale to Pex fittings at West Marine so I am ready to install. Ryan (Lefty Originals) has moved into a much larger facility so I may be able to work on CR in comfort. I am doing his web site, truly awesome teardrops.
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Postby eamarquardt » Sat Dec 10, 2011 11:31 am

bdosborn wrote:I didn't spend that much on my degree. :lol:

Bruce



Neither did he, but his mother and I did and he "graduated" in June but doesn't have his diploma due to a "paperwork" glitch. We're not happy with him and he's working to get the "glitch" taken care of.

Cheers,

Gus
The opinions in this post are my own. My comments are directed to those that might like an alternative approach to those already espoused.There is the right way,the wrong way,the USMC way, your way, my way, and the highway.
"I'm impatient with stupidity. My people have learned to live without it." Klaatu-"The Day the Earth Stood Still"
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Postby Cdash » Sat Dec 10, 2011 8:14 pm

bdosborn wrote:
eamarquardt wrote: If you provide me with the specs for your frame I can have #1 son, with the $100K ME degree that I paid for, run some calculations to tell you how little you've effected the strength of the beam.


I'd be interested in seeing that. Intuitively I would guess that a hole in the side would weaken it more than the top but I didn't spend that much on my degree. :lol:

Bruce

P.S. Why not replace just the portion of pipe below the axle with flexible tubing?

Hose Linky


The stiffness is calculated by summing I+A*D(squared) A is the area of the part and D is the distance from the centroid of the part to the centroid of the whole piece. The I value is calculated as width*height(cubed). This would be done for each side and top and bottom. If you consider the sides, the A*D(squared) is zero since D=0.

I probably didn't explain it well enough, but the impact of a hole is minimal. The cross member is more of a brace, which lessens the impact of a hole even more.
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Postby eamarquardt » Sun Dec 11, 2011 12:54 am

bdosborn wrote:Intuitively I would guess that a hole in the side would weaken it more than the top.......lol:

Bruce



Actually your intuition is exactly the opposite of the reality of the situation. I'll have #1 son do some calcs. I believe he uses "Solidworks".

Cheers,

Gus
The opinions in this post are my own. My comments are directed to those that might like an alternative approach to those already espoused.There is the right way,the wrong way,the USMC way, your way, my way, and the highway.
"I'm impatient with stupidity. My people have learned to live without it." Klaatu-"The Day the Earth Stood Still"
"You can't handle the truth!"-Jack Nicholson "A Few Good Men"
"Some people spend an entire lifetime wondering if they made a difference in the world. The Marines don't have that problem"-Ronald Reagan
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Re: Propane gas line

Postby backstrap bandit » Sun Sep 27, 2015 1:46 pm

U could use pro flex for your gas line it is the corrugated gas line Home Depot sees it very flexible and easy to use and coated
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