My neighbour had a new boiler this last year. He is outside (in the freezing cold) fitting lagging to the gas pipe. The piping was installed by BG: should they have lagged them; do regs require it; is it actually necessary?
I assume it is because LPG may turn to liquid or even freeze: at what temperatures for normal gas supply pressures?
He is daft! Lagging will only slow down the rate of escape of existing heat from the pipe and where is the heat source from a gas tank? There is none. The gas will be colder than ambient as a result of the latent heat of evaporation as it leaves the tank so the insulation will help to keep it colder than ambient along the pipe run. Totally futile exercise. I suppose there could be a slight benefit to lagging the pipe run INSIDE the house to stop condensation forming on the outside on its way to the boiler?
IIRC Butane liquifies around 3C ...
Wikipedia gives -1 to 1 (at atmospheric pressure), a surprisingly large uncertainty I would have thought. I don't think it's going to freeze in there (below -130 C) but I guess it could liquify particularly in weather conditions where the pipe gets colder than the tank (not impossible if the tank is sheltered while the pipe sees clear sky) but, as others say, as gas is evaporating it will cool the liquid in the tank, reducing the gas overpressure.
Bottom line is that I'm inclined to say it is better left unlagged because most of the time it will act as an evaporator, bringing heat into the house.
LPG != Butane!!!
Oops yes, I was just following the OP. My assumption is that UK LPG is a propane/butane blend and probably, as in the US, the blend will vary with the season. (I wonder how pure the "propane" in my gas torch cylinder is).
Doesn't change the logic, though: there could be scope for butane condensation in the pipework.
quote from wikipedia
Varieties of LPG bought and sold include mixes that are primarily propane (C3H8), primarily butane (C4H10) and, most commonly, mixes including both propane and butane. In winter, the mixes contain more propane, while in summer, they contain more butane.[1][2] In the United States, primarily two grades of LPG are sold: commercial propane and HD-5. These specifications are published by the Gas Processors Association (GPA)[3] and the American Society of Testing and Materials (ASTM).[4] Propane/butane blends are also listed in these specifications.
Is he lagging it because there's been a problem, or is he lagging it because "Well, it's a pipe outside, so it needs lagging"?
We've got external LPG piping - both at the house end and the tank end. The house end was, I presume, fitted by FloGas, whilst the other end was fitted 18mo ago by Calor, who also looked closely at the house end. Neither end is lagged.
Our old house had external mains gas piping, fitted by BG, unlagged.
Mostly methane, though: BP -160C.
so what happens in subzero weather?
NT
does he even have LPG?
Jim K
Good point
I was going to say, if he lived in Alaska then they lag the whole lot, tank and all, and as has been said, the evaporation due to the drop in pressure is going to cool it anyway to some extent.
I'd have thought boxing it in so it does not look so ugly might have been time better spent, and that would save it from accidental damage from flying objects in the next gale as well. Brian
Indeed. My reading of this is that his neighbour has normal mains gas, the OP was only offering a suggestion of why he might have been lagging it. Natural gas liquifies at about -160 centigrade.
Tim
You don't use butane. Simples.
Tim
Quite. Even if it's LPG, it's mostly propane, which boils at -42C. Although LPG can contain traces of butane, which might just condense out in exposed pipes at sub-zero temperatures, I suppose. But even liquid butane has a vapour pressure, meaning that small amounts of condensate would soon 'dry out' and disappear.
Maybe the guy just wanted an excuse to get out of the house for a while.....
Are you sure he is lagging the gas pipe and not the condensate pipe?
amateur expressed precisely :
Butane can and does freeze, but it will be propane. No need to lag any pipes anyway, it will not help.
The butane refuses to boil. One solution that I found to this problem was to put the canister in the bottom of my sleeping bag so that I could have hot tea in the morning. :-)
Lpg is a description which includes both Butane and Propane. The normal LPG used in the UK for domestic heating fed from a tank is PROPANE because of the winter temperatures. To the OP there is no point lagging the pipe in the UK
All the caravans with blue gas bottles get cold ;)
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