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K, having the heaviest walls, typically used for underground burial.
L, used for most purposes.
M, with the lightest walls, used for drainage and other low-pressure applications. (Some plumbing codes do not permit M.)

Type K
Nominal Size
(inches) Actual Outside Diameter
(inches) Tolerance on Outside Diameter
(inches) Wall Thickness
(inches)
Annealed1) Drawn2) Nominal Tolerance
1/4 3/8 0.375 0.002 0.001 0.035 0.0035
3/8 1/2 0.500 0.0025 0.001 0.049 0.005
1/2 5/8 0.625 0.0025 0.001 0.049 0.005
5/8 3/4 0.750 0.0025 0.001 0.049 0.005
3/4 7/8 0.875 0.003 0.001 0.065 0.006
1 1 1/8 1.125 0.0035 0.0015 0.065 0.006
1 1/4 1 3/8 1.375 0.004 0.0015 0.065 0.006
1 1/2 1 5/8 1.625 0.0045 0.002 0.072 0.007
2 2 1/8 2.125 0.005 0.002 0.083 0.008
2 1/2 2 5/8 2.625 0.005 0.002 0.095 0.010
3 3 1/8 3.125 0.005 0.002 0.109 0.011
3 1/2 3 5/8 3.625 0.005 0.002 0.120 0.012
4 4 1/8 4.125 0.005 0.002 0.134 0.013
5 5 1/8 5.125 0.005 0.002 0.160 0.016
6 6 1/8 6.125 0.005 0.002 0.192 0.019

Tubes of Type K are used for domestic water-, service and distribution-, fire protection-, solar-, fuel and oil-, HVAC-, compressed air-, natural gas-, LPG gas-, snow melting- and vacuum-systems.

Type L
Nominal Size
(inches) Actual Outside Diameter
(inches) Tolerance on Outside Diameter
(inches) Wall Thickness
(inches)
Annealed1) Drawn2) Nominal Tolerance
1/4 3/8 0.375 0.002 0.001 0.030 0.003
3/8 1/2 0.500 0.0025 0.001 0.035 0.004
1/2 5/8 0.625 0.0025 0.001 0.040 0.004
5/8 3/4 0.750 0.0025 0.001 0.042 0.004
3/4 7/8 0.875 0.003 0.001 0.045 0.004
1 1 1/8 1.125 0.0035 0.0015 0.050 0.005
1 1/4 1 3/8 1.375 0.004 0.0015 0.055 0.006
1 1/2 1 5/8 1.625 0.0045 0.002 0.060 0.006
2 2 1/8 2.125 0.005 0.002 0.070 0.007
2 1/2 2 5/8 2.625 0.005 0.002 0.080 0.008
3 3 1/8 3.125 0.005 0.002 0.090 0.009
3 1/2 3 5/8 3.625 0.005 0.002 0.100 0.010
4 4 1/8 4.125 0.005 0.002 0.114 0.011
5 5 1/8 5.125 0.005 0.002 0.125 0.012
6 6 1/8 6.125 0.005 0.002 0.140 0.014

Tubes of Type L are used for domestic water-, service and distribution-, fire protection-, solar-, fuel and oil-, HVAC-, compressed air-, natural gas-, LPG gas-, snow melting- and vacuum-systems.

Type M
Nominal Size
(inches) Actual Outside Diameter
(inches) Tolerance on Outside Diameter
(inches) Wall Thickness
(inches)
Annealed1) Drawn2) Nominal Tolerance
1/4 3/8 0.375 0.002 0.001  
3/8 1/2 0.500 0.0025 0.001 0.025 0.002
1/2 5/8 0.625 0.0025 0.001 0.028 0.003
5/8 3/4 0.750 0.0025 0.001  
3/4 7/8 0.875 0.003 0.001 0.032 0.003
1 1 1/8 1.125 0.0035 0.0015 0.035 0.004
1 1/4 1 3/8 1.375 0.004 0.0015 0.042 0.004
1 1/2 1 5/8 1.625 0.0045 0.002 0.049 0.005
2 2 1/8 2.125 0.005 0.002 0.058 0.006
2 1/2 2 5/8 2.625 0.005 0.002 0.065 0.006
3 3 1/8 3.125 0.005 0.002 0.072 0.007
3 1/2 3 5/8 3.625 0.005 0.002 0.083 0.008
4 4 1/8 4.125 0.005 0.002 0.095 0.010
5 5 1/8 5.125 0.005 0.002 0.109 0.011
6 6 1/8 6.125 0.005 0.002 0.122 0.012

Tubes of Type M are used for domestic water-, service and distribution-, fire protection-, solar-, fuel and oil-, HVAC-,  snow melting- and vacuum-systems.

1 in (inch) = 25.4 mm
1) Annealed tube is suitable for use with flared or compression fittings, and with solder-type fittings, provided rounding and sizing of the tube ends is performed where needed.

2) Drawn temper tube is suitable for use with solder-type fittings. Types A and B tube, in the drawn temper, are suitable for use with certain types and sizes of compression fittings. The standard length for drawn tubes are 20 ft (6.096 m).

The B88 specification covers seamless copper water tube suitable for general plumbing, similar applications for the conveyance of fluids, and commonly used with solder, flared, or compression-type fittings. The type of copper water tube suitable for any particular application is determined by the internal or external fluid pressure, by the installation and service conditions, and by local requirements. Means of joining or bending are also factors that affect the selection of the type of tube to be used.

This specification is the imperial companion of Specification B 88M.