We get asked this question regularly… and understandably, given the amount of emergencies caused by burst water pipes our engineers have to deal with, and the fast answer is no, it is highly unlikely unless the gas line itself is faulty.
Gas, as it is delivered to the typical home, is too dry to cause any concern about it freezing. For a gas mains supply or externally mounted gas pipe to freeze, there would need to be water in the gas line, where it can accumulate in a low spot before there might be any possibility of freezing. Such a presence of water would have had to be left there during the installation process or by improper repair of the line by the utility company.
Mains supply pipes are highly pressured and so they are made to be resilient. A pipe containing natural gas would have to get extremely cold to freeze – actually about 296.7° degrees Fahrenheit – and would need to be struck with a sledgehammer before there would be any possibility of it breaking. So, freezing gas is probably not a worry, even in the UK’s worst winters!
In terms of home appliance piping, ideally all gas pipes that have been set into walls should be protected from the effects of corrosion caused by concrete, or setting plaster with a barrier of some kind.
However, any condensation waste pipes leading from boilers (usually a 22mm white plastic pipe or larger 32mm black /grey/white waste pipe) should be protected with proprietary pipe lagging, due to the presence of water.
Gas can leak for many reasons though. Make sure all your gas appliances are installed properly and serviced regularly, and never try and tackle any repairs or pipe connections yourself. Do not delay in contacting a properly registered engineer if you suspect a leak in your home.