on 2003-09-17 01.06, Michael Payne at [EMAIL PROTECTED] wrote:
> 
> It might surprise you to know that the common copper plumbing pipe sold in
> the US is actually hard metric, cannot remember exactly, I think the 1/2"
> is 15 mm and the 3/4" is 22 mm, it's just called inch size for the benefit
> of Americans, no idea when it happened, but it's definitely hard metric.

Dear Michael,

Same here � sort of. The other day, I had occasion to measure a 'half-inch'
pipe. It had an internal diameter of 10 millimetres and an external diameter
of 12 millimetres, giving it a wall thickness of 1 millimetre.

Not a 12.7 mm anywhere!

I'm not sure if this was a 'standard' pipe or a 'special'. I will
investigate further.

Cheers,

Pat Naughtin LCAMS
Geelong, Australia

Pat Naughtin is the editor of the free online newsletter, 'Metrication
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