All the windmills in the UK are not supplying enough electricity to charge one I phone in every house in the country

[tony sayer]

I remember back a long while ago they had an open day of sorts where you could go on or in a section of pipe to see how it was welded and inspected;!..

[Jethro_uk]

send robotic pigs through empty pipes to check for corrosion. They had to notify the CAA when venting the pipes, as it made the air above too thin for safe flight !

[The Other Mike]

All major gas venting sites are marked on aircraft navigation charts with a minimum advised height.

No idea why they would ever need to inform the CAA as I can't ever recall them being in a NOTAM (notice to airmen) as they are regarded as a fixed hazard just like TV masts and chimney stacks.

Example of one near Duxford mentioned previously and the key from a CAA supplied chart.

[Jethro_uk]

AFAICR the location of pipes and offtakes was kept as secret as possible (with the exception of pipes crossing rivers, which had to be marked) as you really wouldn't want to see what a few pounds of HE could do there.

[geoff]

In message , Clive Page writes

Keep up at the back there ...