Home Studio Topics — plumbing for fuel gas

Writers note: this is an expansion on an earlier “quick and dirty” article “Plumbing Propane for the Glassworking Torch“.

As we all know (or at least I hope we all know by now), it is illegal to keep more than two one-pound cannisters of propane in your house or garage at any given point in time. If you are using a 20# propane tank (the kind most often found on bbq’s), this of course means it must be kept outside.

If you disconnect your fuel gas line (standard “T” grade welding hose) at the end of every session, a loophole in the NFPA code allows the line to be routed through an open door or window. This is considered a temporary connection, and as long as you religiously disconnect the line every day, this type of connection is permitted under code.

A more permanent connection requires wall penetration of some kind. There is nothing in the code that requires the wall penetration to actually be through the wall however. A window or a door can be used, provided that that the requirements of the code are followed. That may sound like a contradiction to what I just wrote above but stick with me for a bit.

If you are already using a window or door for your ventilation system, this usually means that you have blocked the opening, usually with a piece of plywood to which your intake or exhaust duct is mounted. Since this is considered a more or less permanent blockage, there is nothing prohibiting this same piece of plywood from acting as your wall penetration point.

Ah-ha!!! (can you see the light bulb alight over your head?)

NFPA code requires that any “permanent” wall penetration be done with metallic pipe, but does not state what kind of pipe must be used. Here are your basic choices: stainless steel, so-called “black” pipe (which is actually iron), galvanized, or copper (typically soft wall). Personally, I prefer to use galvanized. You do not need special left hand threads, the standard right hand thread is sufficient for our purposes.

You will need the following items (I suggest that you use 1/2″ pipe):

  • 1 each – straight 10″ (this will provide enough length if you have 6″ outer wall studs)
  • 2 each – ball type shut off valve rated for fuel gas (check with the hardware people, don’t purchase a valve rated only for water or air)
  • 1 each – 1/2″ male NPT (national pipe thread) to 1/4″ barbed hose connector
  • 1 each – 1/2″ male NPT (national pipe thread) to standard fuel gas flare fitting

Note: you may need to purchase additional couplings and/or fittings to achieve the end result, show this list (along with the picture below) to the guy (or gal) at the hardware store, and if he/she has any knowledge at all, he/she should be able to get you what you need.

Also required: either a spool of teflon pipe thread tape –OR– fuel gas rated pipe sealant compound.

Also required: outdoor rated hole sealant – this can be either the pressurized cannister type of expanding foam or the moldable putty. This is used to seal the opening around the pipe and the plywood.

Drill a hole in the plywood 5/8″ in diameter to allow for the pipe to slide through the hole.

Apply pipe sealant or teflon tape to one end of the long pipe and the male barbed fitting. Thread shut off valve onto the pipe and the barbed fitting into the the other end of the shut off valve. Using pipe wrenches, tighten the valve and barbed fitting as tightly as possible. Use a rag to clean up any excess pipe sealant.

Push the pipe through the hole in the plywood and have a helper hold the pipe in place with a pipe wrench. Go outside and repeat the process: apply pipe sealant to the pipe and the the flare fitting, attach the valve to the pipe and the flare fitting to the valve, tighten with pipe wrench. Use a clamp to hold the pipe in place so that it cannot move.

Use sealant to fill around the opening in the plywood.

Attach a flexible metal fuel gas hose to the flare fitting on the pipe. and your “T” grade fuel gas hose to the barbed fitting.

To make the connection to your regulator, you are going to need a special “B” to 1/4″ pipe thread adapter, which is available at most welding supply houses — your hardware store **WILL NOT** have this fitting. (Western Enterprises Part # 33, 1/4″ NPT to LH “B”)

I strongly recommend the use of a regulator side quick disconnect to make changing out of the propane tank easier.

Attach the main part of the quick disconnect to the regulator. The the “B” to 1/4″ NPT fitting will attach to the removable piece of the quick disconnect. You may need several adapters to get from the 1/4″ NPT fitting to the flare fitting required for the flexible fuel gas line, attach as necessary, but note that “B” fittings and flare fittings do not need and you should not use pipe sealant of any kind. The only time pipe sealant is required is when using NPT threads.

One note on the pictures below: you will see that I do not have a shut off valve on the outside, this is because the fuel tank itself is 10 feet or less from the point of entry through the wall (actually a slab door). Code permits this provided there is an easily accesible shut off valve on the tank. Since there is both a shut off valve AND the regulator can be turned off, this meets the requirements of the NFPA code.




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