Welded tubes & pipes (ERW, SAW) · Size & tolerance table

Black and galvanized pipe for threading (EN 10255, formerly BS 1387 and DIN 2440)

Standard: EN 10255 (series M and H) formerly BS 1387 (medium and heavy), DIN 2440 (medium), DIN 2441 (heavy)

These are the welded "water and gas" tubes threaded with ISO 7-1 (BSP taper) threads and supplied black or hot-dip galvanized, the standard pipe for plumbing, fire-fighting, gas and general services in the GCC. EN 10255 replaced BS 1387 and DIN 2440/2441 and kept their dimensions: series M is the old BS 1387 Medium (blue band) and series H the old Heavy (red band).

Pipe is specified by DN or inch size and series, for example "EN 10255 M, DN 25, galvanized, screwed and socketed". The outside diameter is set by a maximum and minimum rather than a single figure, so that the thread can be cut on any tube within the range.

Series M (medium) and H (heavy)

Size		Outside diameter		Series M			Series H
DN	Size in	Max mm	Min mm	t mm	Plain end kg/m	Screwed & socketed kg/m	t mm	Plain end kg/m	Screwed & socketed kg/m
10	3/8	17.4	16.8	2.3	0.839	0.846	–	–	–
15	1/2	21.7	21.1	2.6	1.21	1.22	3.2	1.44	1.45
20	3/4	27.2	26.6	2.6	1.56	1.57	3.2	1.87	1.88
25	1	34.2	33.4	3.2	2.41	2.43	4.0	2.94	2.96
32	1 1/4	42.9	42.1	3.2	3.10	3.13	4.0	3.80	3.83
40	1 1/2	48.8	48.0	3.2	3.57	3.61	4.0	4.38	4.42
50	2	60.8	59.8	3.6	5.03	5.10	4.5	6.19	6.26
65	2 1/2	76.6	75.4	3.6	6.43	6.55	4.5	7.93	8.05
80	3	89.5	88.1	4.0	8.37	8.54	5.0	10.3	10.5
100	4	114.9	113.3	4.5	12.2	12.5	5.4	14.5	14.8
125	5	140.6	138.7	5.0	16.6	17.1	5.4	17.9	18.4
150	6	166.1	164.1	5.0	19.7	20.3	5.4	21.3	21.9

Masses are for black tube; galvanizing adds about 3–8%, more on the smaller sizes.

BS 1387 Light series (brown band, withdrawn)

The light series of BS 1387 is still quoted by some mills for non-pressure and structural uses. It has no direct equivalent in EN 10255, whose light series L, L1 and L2 have their own walls and diameter limits; check the wall on the order.

DN	Size in	OD max mm	OD min mm	t mm	Plain end kg/m	Screwed & socketed kg/m
10	3/8	17.1	16.7	1.8	0.670	0.676
15	1/2	21.4	21.0	2.0	0.947	0.956
20	3/4	26.9	26.4	2.3	1.38	1.39
25	1	33.8	33.2	2.6	1.98	2.00
32	1 1/4	42.5	41.9	2.6	2.54	2.57
40	1 1/2	48.4	47.8	2.9	3.23	3.27
50	2	60.2	59.6	2.9	4.08	4.15
65	2 1/2	76.0	75.2	3.2	5.71	5.83
80	3	88.7	87.9	3.2	6.72	6.89
100	4	113.9	113.0	3.6	9.75	10.00

Notes

Threads per inch: 19 for DN 10, 14 for DN 15 and 20, 11 for DN 25 and larger (ISO 7-1 / BSP).
Standard length 6 m (also 6.4 m); bundle sizes follow the mill, typically 169 pieces of DN 15 down to 7 pieces of DN 150.
The DIN 2440 medium tube had slightly thinner walls (2.65 mm for DN 15, 3.25 mm for DN 25) than BS 1387 Medium; tubes made to it are still found in older installations.