copper tube


Copper pipe is used both by plumbers and for air conditioning (ACR), and the two fields have different ways of sizing the pipe.

Pipe for residential plumbing, or “plumbing tube,” is sold in nominal sizes which are 1/8 inch less than the actual outside diameter. There are three series (plus DWV):

Wall thickness varies with nominal size. The resulting inside diameter is always within a few hundredths of an inch of the nominal size.


Types K and L are available in two tempers:

Flare fittings may be installed on annealed temper pipe, but not on drawn temper; both types can be soldered or brazed.

The table below shows all available K, L and M sizes to 2 inches. Sizes 2½, 3, 3½ and 4 are also made.

Size Actual
outer diameter,
Actual inner diameter, inches
3/8 1/2 0.402 0.430 0.450
1/2 5/8 0.528 0.545 0.569
5/8 3/4 0.652 0.668 0.690
3/4 7/8 0.745 0.785 0.811
1 1 1/8 0.995 1.025 1.055
1 3/8 1.245 1.265 1.291
1 5/8 1.481 1.505 1.527
2 2 1/8 1.959 1.985 2.009
in these forms 
drawn temper 20-foot
annealed temper 60-foot, 100-foot,
and 200-foot coils
60-foot, 100-foot,
and 200-foot coils
not made


A fourth type, DWV (for drain waste vent) is sold only in drawn temper and in sizes from 1¼ inch to 8 inches. It comes in 20-foot lengths. The sizes usually used are 1¼ inch, 1½ inch, 3 inches, and 4 inches.


Pipe for use in air conditioning and refrigeration is designated ACR. It is sized by the actual outside diameter and comes in lengths of 20 feet in hard temper and coils of 50 feet in soft temper.

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