How to hang gas line under rv and when to paste before or after hanging

[59as]

Hi, I'm going with black pipe and have about four sections should I put the dope on and seal before or after I hang the pieces, I'm afraid that if I do it before they will leak from movement to get it up etc. but if I do it when connected to the underside it will be difficult to make turns and get all of the fitting lined up correctly underneath. Hope this makes sense and I'm going with a paste and not yellow tape since I've read here that it seems to be the new standard. Also do I need to put hose between hangers and pipe and underside aluminum?

Love you all and hope to God that I leave my driveway in this thing one day!

[HowieE]

Dope is the preferred method for black pipe. You are working with low pressure gas so it is unlikely you will move a given joint while placing the system up under the trailer so dope before.

How are you going up into the trailer? Flared copper is the correct method.

[wahoonc]

FWIW my trailer is plumbed with copper LP lines. they are put together with flare fittings and are held to the underside of the belly with rubber lined p-clamps.

Aaron

[perryg114]

Black pipe would not be my first choice. I would go with copper. Black pipe is expensive and heavy. Also joints are more prone to leak than flared copper. I prefer Teflon tape for pipe joints. I have never been able to get paste to seal. If Teflon tape is used properly it won't leak at all.

Perry

[Protagonist]

I believe RVIA code calls for copper, because it will flex as your trailer flexes. As for hanging it, the bare minimum is one hanger at each joint or each change in direction of the tubing if you bend the tubing to form elbows.

[wahoonc]

Originally Posted by Protagonist

I believe RVIA code calls for copper, because it will flex as your trailer flexes. As for hanging it, the bare minimum is one hanger at each joint or each change in direction of the tubing if you bend the tubing to form elbows.

RVIA Code doesn't specify, only that joints be accessible for inspection. I have seen black pipe, copper as well as rubber hoses used for plumbing the LP systems. Look under some of the new SOB's and you will see that they are using rubber hoses with fittings attached with zip ties.

I am old school and my first choice is going to be copper.

Aaron

[Lets travel]

I would not use black pipe to much vibration, copper would be much better.

[HiHoAgRV]

My '63 had the main manifold run with black, copper ran up and into the shell. I went back with all copper, it was much easier in my opinion.

[perryg114]

The black iron pipe of today is made in China and tends to be porous.

Perry

[r carl]

Originally Posted by perryg114

The black iron pipe of today is made in China and tends to be porous.

Perry

Just like their tires.

[A W Warn]

When I had to make a repair, I used flexible copper and flare type brass compression fittings. I slid each piece of the copper pipe inside a slightly shorter length of PEX pipe before making the flare, so that the PEX would act to protect the copper from road debris. This way the flare fittings are accessible and there is no wear on the copper pipe from the hangers.
I used this type of hanger, slightly larger than the diameter of the PEX.




add edit:
If you decide to use the black iron pipe, don't forget to use a dielectric adapter fitting at every location where iron transitions to brass/copper. If you do not use these fittings, galvanic action will corrode the pipe quickly. These fittings just slow the process down. There will still be corrosion at these dissimilar fittings.

[Panama Red]

I went straight copper, flair fittings, all the way. It held up for 40 years, and I'll be dead before another 40 rolls around...

-Red

[J. Morgan]

I needed a 3/4" supply line to run my on demand hot water heater, so I used black pipe secured about every foot.

I built it in place with pipe dope.