I need to replace a bit of central hearing oil pipe which measures 10mm OD.
If I get some pipe and fittings which are quoted as being 10mm, will I get what I want, or might I get something that is (say) 10mm ID, 12mm OD? What's the standard terminology? Most adverts seem very reluctant about making such things clear.
I note that plastic and rubber pipes seem to be referred to by their ID, and usually both ID and OD are quoted.
mETRIC SIZES are tubes, the outside diameter is the controlled dimension. Imperial sizes are pipes, the internal diameter identifies the pipe size.
I assume it's copper. Asking for 10mm should get the right fittings. Browse the BES catalogue on line, they stock nearly everything.
That's a slight over-simplification!
Imperial copper pipes are indeed designated by the *nominal* bore - so that, for example a "half inch" pipe is very similar in size to a metric
15mm tube. However, all 1/2" copper pipes have the same standardised OD- so that fittings will fit(!) - and the *actual* bore can be different, depending on the wall thickness.
Yes, that is why I said the "internal diameter identifies the pipe size", because 1/2" pipe may not be exactly 1/2" bore, but it is still called 1/2" pipe.
because 1/2" pipe may not be exactly 1/2" bore, but it is still called 1/2" pipe.
And not all 1/2" pipes have the same bore as each other - which is why I referred to "nominal" bore.
Let me say thanks for the advice. I'm sure that these quirks are obvious and second nature to those in the know, but for those DIYers who aren't, I guess that caveat emptor applies.
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