gas pipes

[davidj]

I'm just about to start on the gas pipes for my 20x30 and it's my first time using steel pipe for anything non-trivial (although it's still a pretty small job - 1 x on-demand water heater, stove and refrigerator).

What's the best way of getting the right length for the pipe?  Is it essential to get a pipe threading tool?  Or is it reasonable to get the h/w store to cut it for me where necessary and just use the appropriate length nipples for tweaking the small runs?

Also, I'm gonna need 3/4" for the water heater.  Should I just do 3/4" everywhere (given the stove and fridge are pretty much on the way between the propane tank and the w/h)?  Or should I really do 1/2" for the rigid vertical stubs to the kitchen (but size the valves and flexible connections appropriately)?

Any other hints and suggestions?  Start from the end and work back to the entry point or start from the entry point and work to the end?

Thanks.

[glenn kangiser]

I generally get by fine using the proper length nipples.

I use coated pipe underground with all connections taped with 10 mil tape until out of the ground.  I use a good coat of PTFE paste recommended for gas on all connections.  I no longer ever use Teflon tape.  Too many leaks with it.

Make sure it is full size to the appliances that need it - I reduce the rest to 1/2" as needed.

[MountainDon]

I'd say there is no sense in using oversized pipe where not necessary. But make sure the size is correct for the appliance and length of run.

Rectorseal makes a great paste that approved for water and gas use. I'm with Glenn on the teflon tape. The only leaking threaded couplings I've ever had were made with teflon tape.

[Shawn B]

First let me say that I have been browsing this site for a few weeks now. Mostly reading owner/builder stories....WOW!! there are lot's of excellent ideas and quite a few true craftsman here.


davidj:  I would ask if you are using LP or Natural Gas? But I see you list a refrigerator, so will assume you are using propane? Also you mention a on demand water heater. This can use upwards of 170,000 Btu's when in use. 3/4 black iron pipe when using propane at 30 feet is at least 300,000 btus. 1/2 black iron pipe for propane at 30' is 150,000 btu. These would have to be devalued some for high altitude. These are "rules of thumb" that I use. But if you check they will be within specs. Without seeing your piping diagram for appliance branches or lengths I would recommend starting with 3/4 inch black pipe, add a 3/4 inch tee for future use cap or plug the tee outlet. Also check to see if the water heater will need a 3/4 inch line to it. The range and refrigerator can be serviced off the same 1/2 branch line. Actually the whole cabin MIGHT be able to be serviced by 1/2 but the water heater is the wild card. For small jobs like these you should be able to do some rough measuring and have the hardware store cut some custom nipple lengths. I have found that 12', 18", and 24" nipples come in handy with a standard nipple tray. Also you might consider renting a pipe vise and hand threader (meaning manually powered) to make nipples on sight. Hope this helps.

[rick91351]

Welcome Shawn 

Thanks, sounds as if you have installed propane lines before.  We are sort of thinking going with some propane when we start our build.  Can I drop you a line if we have some questions away from a salesman?