Author Topic: (Revised) Gas line schematic(s)... please review and comment  (Read 6359 times)

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Offline NM_Shooter

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(Revised) Gas line schematic(s)... please review and comment
« on: September 01, 2010, 06:39:53 AM »
Okay... here is the simple schematic I drew up for this thing.  

Keep in mind that as far as you or the state are concerned, this is a storage building out in the middle of the woods.  Not a cabin.  Nope.  

So... I am using RV appliances for this thing.  Originally I was going to do everything in 3/8 copper, but I think the 1/2" black pipe will be a lot more durable since most of the lines will be exterior to the cabin.  I like Don's system of having valves for each appliance, but I have not decided if I am going to use them or just keep it simple.  I like simple so far.  

Okay.. here is the sketch.  Everything vertically drawn is vertical, same for horizontal.  I'm hoping that it is somewhat readable.  The black pipe to flare connectors will also be outside of the cabin, but under the cabin or under the eave and out of the weather.  This way I will only have the appliance connections inside the cabin.  

Er.... I mean shed.  Not cabin.  Strike that cabin part.

Comments please?

« Last Edit: September 02, 2010, 04:29:28 AM by NM_Shooter »
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Offline NM_Shooter

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Re: Gas line schematic... please review and comment
« Reply #1 on: September 01, 2010, 06:43:59 AM »
Couple more questions (that didn't take long)

What can I use to secure this pipe to the outside of the building?  I'd rather not use uni-strut.  

For the part under the cabin, is there a way to hang it somewhat so that it is suspended a couple of inches below the joists but still secure?

Should I assemble this somewhat in free air and then attach it to the building, or should I secure it to the building and assemble as I go?  Seems like it might be difficult to screw on fittings if the previous piece was attached to the, um, shed.  
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Offline glenn kangiser

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Re: Gas line schematic... please review and comment
« Reply #2 on: September 01, 2010, 07:19:51 AM »
There are wire hangers that you can get - just a simple U with short sharpened L's on the ends that you drive into the joists with a hammer - cheap and quick.

I like the pipes hanging in side and exposed for the Industrial look common in the high class eating establishments - but that's me... [ouch]

I use the flex stainless gas tubes rather than the copper coming off the gas cock - just that I don't trust flared copper although I assume 99.9999% of the time there is no problem with it.
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Offline bayview

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Re: Gas line schematic... please review and comment
« Reply #3 on: September 01, 2010, 09:41:05 AM »

   Please   check all fittings for leaks before using the appliances. . . . .

   I use about 1/3 dishwashing soap, then fill with water in a spray bottle.   Spray on all fittings.

   Any "flexible" lines should be inside and not out in the elements.  Especially copper.   They have a tendency to corrode and get pinhole leaks.

/.
    . . . said the focus was safety, not filling town coffers with permit money . . .

Offline Redoverfarm

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Re: Gas line schematic... please review and comment
« Reply #4 on: September 01, 2010, 09:46:32 AM »
Frank I secured mine on the joist.  Starting at one end and working to the other. You don't have to secure it until you have the fittings going in the right direction and tight.  Just loose fit(jhanging) with 3/4" perforated hanging straps and drywall screws.   I didn't use copper. I used 1/2" BI stubs off of my 3/4" BI supply.  Once I went up through the floor I put a cut off.  Then used the flex stainless gas line off of the valve to the appliance. 

Offline JRR

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Re: Gas line schematic... please review and comment
« Reply #5 on: September 01, 2010, 09:56:17 AM »
I would want a short piece of flex, even if it is a piece of "S" shaped copper, to connect to the tank assembly ... all tanks move a bit, especially if they are bottles.  It will make hooking up a bit easier.  If a short piece of flex corrodes ... just plan to replace it every few years.

Offline MountainDon

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Re: Gas line schematic... please review and comment
« Reply #6 on: September 01, 2010, 10:12:40 AM »
1. Shut offs at or near each appliance take off?  I used pipe thread type and transitioned to the flex that I used after them. You could do the same to the 3/8 copper tubing.  Even though the 3/8" copper tubing has worked well for years in the RV I used flex connectors in the cabin to make connecting easier. Since there's no code inspection up there you could use copper direct from the iron to the appliance, as in an RV, with no issues I'd think.

2. I preassembled some of my pieces as it was easier handling the small pieces in a pipe vice (at home) than to wrestle with them at the cabin.

3. I used some of the perforated strapping for hanging. Two screw pipe straps in a couple places. If you want more secure than that use a couple blocks of wood to space it away from the cabin floor, wall.

4. The drip pipe in the lower left of the schematic may be unnecessary.

5. Some liquid soaps contain substances that promote copper corrosion. I noticed that on some fittings (lots of green crud) under the RV a few years back. I now use a bubble test liquid I bought from an RV dealer. The copper where I've used it has remained free of any corrosion for years.

6. I wouldn't worry about having copper exposed unless they was a danger of it being crushed from impacts. RV's have all sorts of copper tubing running around under them and that's subject to whatever is on the road.  Again, I say that because I know there are no code folks being involved. Different story in your back yard back home.

7. I imagine you are using the RV type flex rubber hose connectors from the regulator to the cylinders.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline MountainDon

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Re: Gas line schematic... please review and comment
« Reply #7 on: September 01, 2010, 10:17:44 AM »
One last thought of mine.... I used an iron pipe union in the pipe below the regulator. That was to make initial installation as well as removal and re-installation of the regulator easier as my iron pipe was only a fraction of an inch off the cabin wall. (Not enough space to allow the regulator to turn to thread/unthread it)  I also have a spare regulator, pre-mounted on a section of black iron pipe with a uniob on the end in case I have to perform a replacement. For some reason I have had some cold weather problems with the RV propane system in the past. This was to help in case that happened with the cabin.
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline NM_Shooter

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Re: Gas line schematic... please review and comment
« Reply #8 on: September 01, 2010, 01:21:43 PM »
Thanks to all for the great advice. 

I'm switching to coated stainless flex lines.  Adding a union below the regulator. 

Found some hangers at Lowes. 

I had planned on running the copper through the floor and up to the appliance, but now I am thinking about running a nipple up through the floor and taking off of the nipple via FPT to flare to the stainless.  That gives me two more joints per appliance in the cabin though....

Hmmmm... maybe I can simplify my setup a bit. 
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Offline NM_Shooter

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Re: Gas line schematic... please review and comment
« Reply #9 on: September 01, 2010, 01:23:27 PM »
How tight do the fittings need to be?  I'm planning on using Rectorseal teflon paste.

-f-
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Offline MountainDon

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Re: Gas line schematic... please review and comment
« Reply #10 on: September 01, 2010, 01:40:07 PM »
How tight do the fittings need to be?  I'm planning on using Rectorseal teflon paste.

-f-

You know, I've been meaning to ask ScottA this very question as he is a real plumber and I am not. 

But, FWIW here goes with what I've done for years. I'll state here that as long as I used a paste like rectorseal, and not tape, I have never had a leak, nor have I twisted off a pipe.

First I make sure the pieces will actually thread together before applying any sealant. Then I apply sealant to the male thread, never the female part. Finger tighten the part. Then turn one full turn but not more than two.

If there is a need to turn a fitting more for proper alignment I let the parts 'downstream' absorb some of the movement after removing or repositioning the anchor pipe wrench.

When I had the cabin gas pipes all fitted I closed the gas valves and used an air pressure adapter that I have for blowing out the RV lines to pressurize the piping to 60 pounds, way more than what the propane will subject the lines to. . It held the air pressure 100% overnight. I also bubble checked the lines before leaving it overnight. Paranoia!

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline davidj

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Re: Gas line schematic... please review and comment
« Reply #11 on: September 01, 2010, 04:33:27 PM »
For pressure testing, you can buy 3/4"->car tire valve adapters with 15psi gauges attached for $10 or so at h/w stores.  Note that regulated propane is a pretty low pressure - more like 1/2 psi - so testing to 15psi still gives a good margin (and, I believe, is in the range they ask for at the inspection).

I guess I don't have Don's talents - my gas system still isn't passing a pressure test.  I pretty much did it as Don said - teflon paste and 1-2 turns.  The first leak was a big one - I couldn't find it with the soapy gas leak detector because I kept checking from one end or the other - the leak was so big the system would be deflated by the time I got to the middle where it was located.  Having my wife man the compressor made it trivial to find - I could hear it!

Now I've got a leak that drops maybe 2 psi/day (starting at 15psi).  I've bought a plug to replace the 15psi gauge and I'm gonna knock it up to more like 50psi and hope it leaks faster so I can find it.  Failing that I guess I just tighten every joint.  Are there any other tricks in this situation?

Offline Shawn B

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Re: Gas line schematic... please review and comment
« Reply #12 on: September 01, 2010, 05:18:01 PM »
NMshooter,

I would used the U shaped hangers that glenn already described or the 2 hole strap hangers. The minerlac (sp) style one hole with a bolt/nut for tightening work well though.

Make sure and keep any of your gas lines well secured and out of the way of any snow dumping off the roof. We had a job a couple winters ago where snow slid off a roof and snapped the nipple off of the gas regulator. Some LP found it's way inside the basement and ignited off the furnace pilot lite. The explosion blew the windows and siding off the front of the house 50 feet into the forest. Thank God it was a flash explosion and nothing ignited in the house except for a few storage boxes, and some Romex wire was badly burnt. We did not originally plumb the gas, but was called in for a re-plumb.

Also the drip leg in the bottom right corner is not correct. There is no change in direction of gas flow. The one in the bottom left is correct but not needed.  Most of the stainless gas connectors stop at 3'.

Buy or borrow a proper pressure test adapter, Lowes usually has them. They screw onto 3/4" male pipe threads and have the air valve stem and gauge already installed. Price is usually around $10. Pump the system up to 15 pounds for at least 30 minutes. Make sure and disconnect the regulator before applying pressure, they are not designed for this much pressure.

Hope this helps
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Offline NM_Shooter

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Re: Gas line schematic... please review and comment
« Reply #13 on: September 02, 2010, 04:28:48 AM »
OK... updated schematic.  You're right, I could only find 3' length coated stainless. 

Some iron now inside the cabin. 

And I'm spooked about leaks.  I'll get a pressure tester today.  Can I hook up appliances and pressure test, or will 15psi ruin the gas solenoids?



Or possibly this one below, depending on how I do the spacing for the appliances...

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Offline MountainDon

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Re: (Revised) Gas line schematic(s)... please review and comment
« Reply #14 on: September 02, 2010, 05:36:06 AM »
Myself, I would do the first where the tee splits to 2 appliances, with a shut off before the split. Then you can pressure test to the valve without danger of damaging any equipment. Then use the bubble stuff on the flex pipe connections.   Or, like you say, the second one if the appliances are more than five or so feet apart.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Shawn B

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Re: (Revised) Gas line schematic(s)... please review and comment
« Reply #15 on: September 02, 2010, 06:51:32 AM »
The first schematic is acceptable per "usual" code. The second one is not because the oven does not have it's own drip leg. However since you are not going to be inspected and you have provided a larger drip leg at the tank regulator I personally would not worry about it, if you have to choose option 2.

Always disconnect all gas appliances and the main regulator when pressure testing. Gas appliances work at pressure levels measured in w.c. (water column). The normal incoming line pressure to a L.P. appliance is 14" w.c., this is less than 1/2 P.S.I. Greater pressure can blow out the diaphragms in the gas valves.

Due as MtDon suggests and bubble check the connections that were not pressure checked.

Also don't worry too much about leaks. Use a good thread sealant like Rectorseal or Gastight etc, cut good clean threads, and tighten the joints snug, pressure and bubble test.
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Offline Redoverfarm

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Re: (Revised) Gas line schematic(s)... please review and comment
« Reply #16 on: September 02, 2010, 11:26:24 AM »
Frank use a 1/2" threaded cap and pressure test to it.  Then when you attach the valves or line then you can bubble check it with the gas on.  Just remember to shut off the gas before breaking any lines open .  I would strongly suggest a main shut off valve and one for for each appliance. If any one of them have to be serviced you might be without two appliances if you only have either the main valve or shared by two appliances.  I think I paid about $8 a valve for the low profile ones.

Offline FrankInWI

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Re: (Revised) Gas line schematic(s)... please review and comment
« Reply #17 on: September 02, 2010, 04:17:39 PM »
This is another one of the posts I'll have to keep handy.  I never knew there was such science to running gas lines.  I just used common sense and will have to go back with a more critical eye on what I did so far.   Thanks!
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Offline NM_Shooter

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Re: (Revised) Gas line schematic(s)... please review and comment
« Reply #18 on: September 02, 2010, 04:34:57 PM »
Whoops.  Just noticed that my last two schematics still call out copper flare in the upper left corner.... this is obviously a typo. 

Thanks to all for the input.  I think I have the pcs accounted for!
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Offline davidj

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Re: Gas line schematic... please review and comment
« Reply #19 on: September 22, 2010, 07:23:51 AM »

I guess I don't have Don's talents - my gas system still isn't passing a pressure test.  I pretty much did it as Don said - teflon paste and 1-2 turns.  The first leak was a big one - I couldn't find it with the soapy gas leak detector because I kept checking from one end or the other - the leak was so big the system would be deflated by the time I got to the middle where it was located.  Having my wife man the compressor made it trivial to find - I could hear it!

Now I've got a leak that drops maybe 2 psi/day (starting at 15psi).  I've bought a plug to replace the 15psi gauge and I'm gonna knock it up to more like 50psi and hope it leaks faster so I can find it.  Failing that I guess I just tighten every joint.  Are there any other tricks in this situation?

Once I got the pressure up to 50psi it was trivial to find the leak - it practically spit the soapy water back in my face!  And it was in exactly the same place as before.   Another turn and it's held pressure for 3 weeks now (+/- 1 PSI or so for temperature changes).

So my comments, based on one gas pipe job:
  • Most fittings don't need huge torque to seal, but some need quite a bit more
  • Even when the connection is tight, there's still another turn in it if you need it
  • Dab-on leak detector is better than spray-on, and a small mirror helps a lot
  • Testing at high pressures is the way to go
  • Get everything cut and in built takes a while, but once the system is built it generally doesn't take long to unscrew a few connections so that you can tighten something even if it's pretty much in the middle of the who setup

Offline NM_Shooter

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Re: (Revised) Gas line schematic(s)... please review and comment
« Reply #20 on: September 22, 2010, 08:22:01 AM »
I noticed that the Lowe's threads also did not seat as deeply as the factory cut threads.  Frequently I could only put 1 to 1.5 turns on the pipe before I had to get the wrenches on it.
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