Propane hoses & Barb fittings plus hose clamps

[surftom]

So I'm replacing the alcohol stove with a LPG one (from West marine) and the dropped-ship stove looks great... but has a barbed fitting for connection.
In reading a little - AYBC - it seems that either copper hose or rubber hose is acceptable - but must have a "permanent" connection at the end of the hose. Nigel Calder does not rank a hose clamp as a permanent connection

so here's my question(s)
- why doesn't copper hose have the same problem as solid copper wire - i.e. work-hardens with vibration and eventually cracks - even if well supported. Seems that the appropriate rubber hose is way better in this regard.

- What's a "permanent" connection on the end of a rubber hose? Even the "factory" crimped ones are like a barbed fitting with a hose clamp(s).

Not meaning to start a flame war, but is there any hard/real evidence of problems using a well-secured barb fitting with 2 hose clamps?

This is all on the low pressure side of the propane regulator remember

Thanks for your considered opinions

Tom

[Maine Sail]

Here's just some of what the ABYC A-1 LPG says:

A-1.9 FUEL LINES

A-1.9.1 As installed, the fuel supply line system and
its components shall be compatible with LPG, and shall
withstand the stresses and exposure of the marine
environment.

A-1.9.2 LPG fuel supply line shall comply with the
construction, performance, manufacturing and test, and
marking requirements of UL 21, LP Gas Hose, or

A-1.9.2.1 be corrosion resistant metallic tubing such
as annealed copper tubing, standard type, Grade K or L,
conforming to ASTM B88-75a, Specifications for
Seamless Copper Water Tube, with a wall thickness of not
less than 0.032 inches (0.815 mm).

A-1.9.3 Flexible LPG supply line shall be equipped
with permanently attached end fittings, such as a swaged
sleeve or sleeve and threaded insert.

A-1.9.4 Metal tubing shall be connected by means of
flare fittings
NOTE: “Long nut” flare fittings should be used. The
short nut type fitting used in refrigeration systems can
precipitate fatigue failure due to vibration.

A-1.9.5.2 A flexible LPG fuel line section shall be
used to allow free swing of gimbaled stoves.

A-1.9.5.4 Fuel supply lines shall be protected by close
fitting grommets, sleeves, or sealant of non-abrasive
material wherever they pass through decks or watertight
bulkheads, and the method used shall be watertight.

A-1.9.5.5 Fuel supply lines passing through bulkheads
that need not be watertight shall be installed so that the
bulkheads will not cut, abrade, or damage the line.

A-1.9.5.6 Fuel supply lines shall be continuous lengths
of tubing, piping, or hose from the regulating device,
solenoid valve, or leak detector to the appliance, or to the
flexible section at the appliance.


Considering that I have personally had annealed copper fail, due to fatigue, in my refrigeration system, I personally would NEVER use it on a marine LPG system. I'm amazed that the ABYC still has not made the move to LPG hose... Don't get me wrong properly installed (key word properly) annealed copper is fairly durable but just not for me...

The factory technician for Sea Frost personally did the install on my boat and still I had a tube fail right at the end of the flare nut after only 5 years so I don't trust that "longer" flare nuts will work all that much better. ANY tubing failure on LPG is very, very dangerous luckily for me it was R134 refrigerant and not LPG... I fixed that tube and supported it better and as of yet no issues...

[surftom]

Halehai...
That's the same passages I read.. It's the A-1.9.3 section that had me questioning the conformity of using hose clamps. How the heck would a "threaded insert" work on a rubber hose anyway

I'd much rather use the LPG rubber hose than the copper for the very reason you mention above!

Tom

[Maine Sail]

The term "threaded insert" refers to a fitting that has been permanently swaged to the end of the hose, at the manufacturer, and has either a male or female NPT threaded fitting to which you make your connection using gas type yellow teflon tape or gas rated pipe dope..

It is far simpler to order a pre-made LPG hose that meets the UL requirements. ABYC A-1 does not mandate UL approved and listed hose just that it meets the requirement set forth under the UL LPG hose guidelines..

[Gary1]

I did a quick search and found that Defender.com has a 25 foot, pre-terminated gas supply line. Maybe that would fill your need.

For what it's worth, Breeze has a couple of rubber flex lines in the propane system with 1/4 copper the rest of the way. The copper will work harden if you bend it often enough but if all you're doing is uncoiling it and then running it in a fairly straight line to the stove, that shouldn't be a problem.

If you want or need a longer or shorter, custom-made gas line, go to any good welding supply shop and they can make it for you. There's almost always an Air-Gas shop in every decent sized town in the US. They could also probably sell you just the fittings to do a 'hand swage' on the hose.

[sailingdog]

The real problem with copper LPG lines on a boat is that the copper work hardens and fatigues from vibration. So, unless it is very well supported, it can become a serious problem. The copper line on my LPG stove is all of four inches long...the rest is flexible hose.