On 10/10/2019 20:14, Brian Gaff wrote:
Well one way is that in many older systems the gas pipes are knackered. When
they dug up our road after reports of gas it transpired that our clay soil
was all that was containing a lot of the gas supplies, since the pipes had
rusted away, indeed as they disturbed the pipes gas started to bubble up in
peoples gardens and killed some plants, including one of my roses. They have
since used plastic pipes to replace them all, but as I have no gas
installed, they just left a stop end here ready in case its needed in
future.
I was amazed that they let it go this far, but apparently its not uncommon
for water leaks to get into the clay and leach out in the gas supply, even
to cut it off on low spots.
Both gas and water have extensive contracts going on replacing the now very
old pipes, in the case of gas because they are obviously steel and rusting
away, and in the case of water mainly due to them being made of lead, which
although probably safe after all this time does deteriorate of course.
Brian

Lead pipes in soft-water areas never get a coating and remain soluble.
The water companies use phosphate dosing to prevent the water dissolving
small quantities of lead (I designed some of the dosing rigs in this
area). Other than that, lead pipes can last hundreds of years, as lead
is very stable.

SteveW