ASTM B88 Copper Tubes | Types K, L, M Copper Tubes

ASTM B88 copper tubes are seamless copper water tubes suitable for general pluming, similar applications for the conveyance of fluids. These tubes are available in nominal or standard size 1/2″ through 12″, and are classified into three types according the wall thickness: Type K, Type L, and Type M. They shall be marked with different color codes: green for Type K copper tubes, blue for Type L copper tubes, and red for Type M copper tubes. ASTM B88 seamless copper tubes can be made from commercially pure copper grades UNS C10200, C12000, or C12200. They are commonly used with solder, flared, or compression-type fittings depending on its end connection types.

Chemical Composition Requirements

The chemical composition by product analysis for each ASTM B88 copper grade shall be in accordance with:

• UNS C10200: Copper≥99.95%; Phosphorus: not applicable.
• UNS C12000: Copper≥99.90%; Phosphorus: 0.004-0.012%.
• UNS C12200: Copper≥99.90%; Phosphorus: 0.015-0.040%.

Tempers & Mechanical Properties

ASTM B88 copper tubes shall be manufactured by the seamless process involving hot-working, cold-working, and annealing processes as to produce a uniform wrought structure in the finished tube. The tubes may be furnished in either coiled or straight length. They are generally furnished in three tempers which are listed below along with mechanical property requirements and product forms:

• Temper designation: O60, known as “soft anneal”; Product form: straight lengths or coils; Rockwell hardness (Scale F): ≤ 50; Tensile strength: ≥ 30 ksi; Average grain size: ≥ 0.040 mm.
• Temper designation: O50, known as “light anneal”; Product form: straight lengths or coils; Rockwell hardness (Scale F): ≤ 55; Tensile strength: ≥ 30 ksi; Average grain size: ≤ 0.040 mm.
• Temper designation: H58, known as “drawn”; Product form: drawn; Rockwell hardness (Scale 30T): ≥ 30; Tensile strength: ≥ 36 ksi; Average grain size: N/A.

Tests & Inspection

Visual inspection, dimensional examination, chemical analysis, tensile test, hardness test, expansion test, flattening test, microscopical examination for susceptibility to hydrogen embrittlement, eddy current test, grain size examination.

Sizes, Dimensions, Tolerances & Weight

N.S.	O.D. inch	Tolerance of O.D. Annealed inch	Tolerance of O.D. Drawn inch
1/4"	0.375	0.002	0.001
3/8"	0.500	0.0025	0.001
1/2"	0.625	0.0025	0.001
5/8"	0.750	0.0025	0.001
3/4"	0.875	0.003	0.001
1"	1.125	0.0035	0.0015
1-1/4"	1.375	0.004	0.0015
1-1/2"	1.625	0.0045	0.002
2"	2.125	0.005	0.002
2-1/2"	2.625	0.005	0.002
3"	3.125	0.005	0.002
3-1/2"	3.625	0.005	0.002
4"	4.125	0.005	0.002
5"	5.125	0.005	0.002
6"	6.125	0.005	0.002
8"	8.125	0.006	+0.002 -0.004
10"	10.125	0.008	+0.002 -0.006
12"	12.125	0.008	+0.002 -0.006

*Table I: Nominal sizes (N.S.), actual outside diameters (O.D.), tolerances for O.D. of tubes in annealed condition, tolerances for O.D. of tubes in drawn condition, applicable to ASTM B88 seamless copper water tubes of Type K, Type L, and Type M.

N.S.	Type K W.T. inch	Tolerance of W.T. inch	Weight lb/ft
1/4"	0.035	0.0035	0.145
3/8"	0.049	0.005	0.269
1/2"	0.049	0.005	0.344
5/8"	0.049	0.005	0.418
3/4"	0.065	0.006	0.641
1"	0.065	0.006	0.839
1-1/4"	0.065	0.006	1.04
1-1/2"	0.072	0.007	1.36
2"	0.083	0.008	2.06
2-1/2"	0.095	0.010	2.93
3"	0.109	0.011	4.00
3-1/2"	0.120	0.012	5.12
4"	0.134	0.013	6.51
5"	0.160	0.016	9.67
6"	0.192	0.019	13.9
8"	0.271	0.027	25.9
10"	0.338	0.034	40.3
12"	0.405	0.040	57.8

*Table II: Wall thicknesses (W.T.), tolerances for wall thicknesses, and unit weight of ASTM B88 Type K copper tubes. It is the thickest of the three types. Type K copper tubes are mainly used in underground installations, where the tube needs to withstand higher pressure or resist potential external damage.

N.S.	Type L W.T. inch	Tolerance of W.T. inch	Weight lb/ft
1/4"	0.030	0.003	0.126
3/8"	0.035	0.004	0.198
1/2"	0.040	0.004	0.285
5/8"	0.042	0.004	0.362
3/4"	0.045	0.004	0.455
1"	0.050	0.005	0.655
1-1/4"	0.055	0.006	0.884
1-1/2"	0.060	0.006	1.14
2"	0.070	0.007	1.75
2-1/2"	0.080	0.008	2.48
3"	0.090	0.009	3.33
3-1/2"	0.100	0.010	4.29
4"	0.110	0.011	5.38
5"	0.125	0.012	7.61
6"	0.140	0.014	10.2
8"	0.200	0.020	19.3
10"	0.250	0.025	30.1
12"	0.280	0.028	40.4

*Table III: Wall thicknesses (W.T.), tolerances for wall thicknesses, and unit weight of ASTM B88 Type L copper tubes. It is the intermediate thickness, thinner than Type K but thicker than Type M. Type L copper tubes are commonly used for general plumbing and heating systems, including both residential and commercial buildings.

N.S.	Type M W.T. inch	Tolerance of W.T. inch	Weight lb/ft
1/4"	-	-	-
3/8"	0.025	0.002	0.145
1/2"	0.028	0.003	0.204
5/8"	-	-	-
3/4"	0.032	0.003	0.328
1"	0.035	0.004	0.465
1-1/4"	0.042	0.004	0.682
1-1/2"	0.049	0.005	0.940
2"	0.058	0.006	1.46
2-1/2"	0.065	0.006	2.03
3"	0.072	0.007	2.68
3-1/2"	0.083	0.008	3.58
4"	0.095	0.010	4.66
5"	0.109	0.011	6.66
6"	0.122	0.012	8.92
8"	0.170	0.017	16.5
10"	0.212	0.021	25.6
12"	0.254	0.025	36.7

*Table IV: Wall thicknesses (W.T.), tolerances for wall thicknesses, and unit weight of ASTM B88 Type M copper tubes. It is the thinnest of the three types. Type M copper tubes are used in low-pressure applications such as residential water supply and distribution where local codes permit.

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