tony sayer wrote:

In article , Jethro_uk

When I worked for British Gas "Central Control", we'd vent cubic
*kilometres* of gas from offtakes when undertaking pigging runs. The CAA
had to be informed, as planes flying overhead could conceivably crash ...

What's a "pigging run" please?...

http://en.wikipedia.org/wiki/Pigging

"Pigging in the context of pipelines refers to the practice of
using pipeline inspection gauges or 'pigs' to perform various
maintenance operations on a pipeline. This is done without
stopping the flow of the product in the pipeline.

These operations include but are not limited to cleaning and
inspecting the pipeline. This is accomplished by inserting the
pig into a 'pig launcher' (or 'launching station') - a funnel
shaped Y section in the pipeline. The launcher / launching
station is then closed and the pressure-driven flow of the
product in the pipeline is used to push it along down the pipe
until it reaches the receiving trap – the 'pig catcher' (or
'receiving station')."

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.