What are the dimensional requirements for jis h3300 copper alloy tube?

When you buy seamless copper or copper alloy tubes to JIS H3300, the dimensional requirements are the first thing to pin down. Get the outside diameter, wall thickness, and length right, and the tube will fit, expand, and perform as designed. Get them wrong, and you are looking at rework, leaks, or a failed pressure test.

JIS H3300 is the Japanese Industrial Standard for wrought copper and copper alloy seamless tubes with a round cross-section. It covers grades used in heat exchanger tube bundles, condensers, water supply piping, air conditioning and refrigeration systems, and marine piping. This article walks through the dimensional requirements you need to specify and the tolerances the standard allows.

The Dimensions You Specify

Under JIS H3300, an order is defined by four things:

Outside diameter (OD) or inside diameter (ID)
Wall thickness (WT)
Length
Straightness, for straight tubes

The standard also sorts tubes into two tolerance classes: Ordinary Class and Special Class. Ordinary Class is the default and the more economical choice. Special Class holds tighter tolerances and is worth it when fit-up is critical, for example when tubes are mechanically expanded into thick tube sheets.

Outside Diameter Tolerances

For most JIS H3300 tubes, the outside diameter tolerance depends on the size range and the class you ｓｅｌｅｃｔ.

OD or ID (mm)	Ordinary Class	Special Class
4 ≤ D ≤ 15	±0.08 mm	±0.05 mm
15 < D ≤ 25	±0.09 mm	±0.06 mm
25 < D ≤ 50	±0.12 mm	±0.08 mm
50 < D ≤ 75	±0.15 mm	±0.10 mm
75 < D ≤ 100	±0.20 mm	±0.13 mm
100 < D ≤ 125	±0.27 mm	±0.15 mm
125 < D ≤ 150	±0.35 mm	±0.18 mm
150 < D ≤ 200	±0.50 mm	-
200 < D ≤ 250	±0.65 mm	-
250 < D ≤ 350	±0.4%	-

Wall Thickness Tolerances

Wall thickness tolerance depends on both the OD range and the nominal wall thickness. The table below shows the Ordinary Class values in millimetres.

OD (mm)	WT 0.25–0.4	WT 0.4–0.6	WT 0.6–0.8	WT 0.8–1.4	WT 1.4–2	WT 2–3	WT 3–4	WT 4–5.5	WT 5.5–7	WT >7
4 ≤ OD ≤ 15	±0.06	±0.07	±0.10	±0.13	±0.15	±0.18	-	-	-	-
15 < OD ≤ 25	±0.07	±0.08	±0.10	±0.15	±0.18	±0.20	±0.30	±0.40	±0.45	-
25 < OD ≤ 50	-	±0.09	±0.11	±0.15	±0.18	±0.20	±0.30	±0.40	±0.45	±8%
50 < OD ≤ 100	-	-	±0.15	±0.18	±0.22	±0.25	±0.30	±0.40	±0.45	±8%
100 < OD ≤ 175	-	-	-	±0.22	±0.25	±0.30	±0.35	±0.42	±0.45	±9%
175 < OD ≤ 250	-	-	-	-	±0.30	±0.35	±0.40	±0.45	±0.50	±9%
250 < OD ≤ 300	-	-	-	-	-	±0.40	±0.45	±0.45	±0.50	±10%
300 < OD ≤ 350	-	-	-	-	-	-	±0.50	±0.50	±0.60	±12%

Standard Dimensions for General Piping and Water Supply Tubes

For general piping and water supply tubes, JIS H3300 defines standard nominal sizes with a fixed outside diameter and a choice of wall thickness types, K, L, and M. The tolerance shown is the allowable difference between the average of the maximum and minimum OD at any cross-section and the standard OD.

Nominal Size (A)	Nominal Size (B)	Standard OD (mm)	K Type WT (mm)	L Type WT (mm)	M Type WT (mm)
8	1/4	9.52	0.89	0.76	-
10	3/8	12.70	1.24	0.89	0.64
15	1/2	15.88	1.24	1.02	0.71
-	5/8	19.05	1.24	1.07	-
20	3/4	22.22	1.65	1.14	0.81
25	1	28.58	1.65	1.27	0.89
32	1-1/4	34.92	1.65	1.40	1.07
40	1-1/2	41.28	1.83	1.52	1.24
50	2	53.98	2.11	1.78	1.47
65	2-1/2	66.68	-	2.03	1.65
80	3	79.38	-	2.29	1.83
100	4	104.78	-	2.79	2.41
125	5	130.18	-	3.18	2.77
150	6	155.58	-	3.56	3.10

Heat Exchanger Tube Tolerances

Heat exchanger tubes in grades C4430, C6870, C6871, C6872, C7060, C7100, C7150, and C7164 get a separate set of outside diameter tolerances, expressed as plus-zero / minus values.

OD (mm)	Ordinary Class, WT ≤ 1.1 mm	Ordinary Class, WT > 1.1 mm	Special Class
5 ≤ D ≤ 10	+0 / −0.15 mm	+0 / −0.10 mm	+0 / −0.10 mm
10 < D ≤ 20	+0 / −0.25 mm	+0 / −0.20 mm	+0 / −0.17 mm
20 < D ≤ 30	+0 / −0.40 mm	+0 / −0.30 mm	+0 / −0.22 mm
30 < D ≤ 50	+0 / −0.60 mm	+0 / −0.40 mm	+0 / −0.30 mm

Length and Straightness

Straight tubes are supplied in standard lengths, and JIS H3300 includes tolerances on the bend of straight tubes, in other words straightness. For long tube runs, cumulative deviation becomes a real concern, so confirm the required length and straightness with your supplier before production.

Ordinary Class or Special Class?

Ordinary Class covers most projects and keeps cost down. Special Class is the right call when you need precise fit-up for mechanically expanded tubes, very long tube lengths, or designs with tight cumulative tolerances. If you are not sure which class your design needs, ask your supplier to check the drawing against the JIS H3300 tables before you commit.

Grades Covered by JIS H3300

JIS H3300 covers a broad range of grades, from phosphorus-deoxidized copper C1220 and tough pitch copper C1100 to brasses such as C2801, aluminum brass C6870, and copper & nickel alloy tubes in C7060 and C7150. Each grade brings its own mechanical properties, corrosion behaviour, and typical applications, so the grade and the dimensions go hand in hand.

How to Specify Dimensions When Ordering

To avoid delays, put these details on your inquiry:

Standard and grade, for example JIS H3300 C1220T
Outside diameter and wall thickness, or the nominal size for piping tubes
Length, and whether you need straight tubes or coils
Tolerance class (Ordinary or Special)
Temper (O, OL, 1/2H, H)
Quantity and any additional testing requirements

Get the Right JIS H3300 Copper Alloy Tube

EZ Steel Industrial Co., Ltd. has supplied seamless copper and copper alloy tubes for more than three decades. We produce JIS H3300 copper alloy tube in grades such as C1220, C2801, C7060, and C7150, and we can hold the dimensional tolerances your design calls for, in Ordinary or Special Class. Every order passes through more than 12 quality checkpoints, with hydrostatic and eddy current testing available on request. Send us your dimensions and we will confirm the right grade, temper, and tolerance class for your application.