Sorry TnC2,I should have been more specific in that I had 30...

Sorry TnC2,I should have been more specific in that I had 30 plus years working in a specialist areas related to mine design and safety of underground workings but have no experience in anything to do with valves. Never met any of the deplorables you mention apart from some of the Mine Managers working for British Coal in the Thatcher years. They certainly considered themselves to be a privileged few compared to any of the mine management we dealt with in other countries. Some had personal saunas while the workforce struggled to feed their families. The massive upheaval in the U.K. coal industry came about because mining technology there was about 100 years behind Australian technology with the U.K. unions resisting change in mining methods for generations. As a consequence instead of gradual progressive change they had to advance 100 years in only a few so it had a massive social impact. We all have to wait a while (<100 years) before any Hyundai reports see the light of day so enjoy the roller coaster.DYOR and hang on tight. Cheers DYOR.