Mortimer Schnerd, RN wrote:
....

So what to do? I cut the line with a tubing cutter and was going to solder in
another ported quarter turn valve... only this time to the outside of the water
line shutoff. When I tried to fit the valve on the now open piping, no amount
of stuffing and grunting would get the job done. A visit to the local borg
revealed plenty of 1/2" fittings, only they would fit the thinner M type piping.
I assume I've got L tubing which is just a little thicker.
....

K, L and M are same OD, extra wall thickness comes from ID, not OD.

You have either a non-standard tubing or fittings if they don't fit. A
"real" plumbing supply should be able to supply what you need.

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