BS 1387 HDG Steel Welded Tubes

The BS 1387 HDG steel welded tube refers to a long hollow steel cylinder of circular cross section made by a longitudinal welding process, which is then zinc coated by a hot-dipped galvanization (HDG) process. These tubes may be furnished with plain ends for welding, or screwed ends with a threaded socket (coupling). The screwed ends shall be machined in accordance with BS 21 pipe threads. The BS 1387 steel welded tubes have become a cornerstone of modern construction, playing a vital role in water distribution, fire protection, and structural support, etc.

Sizes, Thickness Series, Dimensions & Masses

BS 1387 hot-dipped galvanized (HDG) steel welded tubes are available in nominal sizes DN 8 to DN 150 in three series of thickness, designated light, medium and heavy. These technical parameters are presented in the tables below.

DN	NPS	OD max. mm	OD min. mm
8	1/4	13.6	13.2
10	3/8	17.1	16.7
15	1/2	21.4	21.0
20	3/4	26.9	26.4
25	1	33.8	33.2
32	1-1/4	42.5	41.9
40	1-1/2	48.4	47.8
50	2	60.2	59.6
65	2-1/2	76.0	75.2
80	3	88.7	87.9
100	4	113.9	113.0

*Maximum & minimum outside diameter of BS 1387 light duty steel tubes.

DN	W.T. mm	Mass-1 kg/m	Mass-2 kg/m
8	1.8	0.515	0.519
10	1.8	0.670	0.676
15	2.0	0.947	0.956
20	2.3	1.38	1.39
25	2.6	1.98	2.00
32	2.6	2.54	2.57
40	2.9	3.23	3.27
50	2.9	4.08	4.15
65	3.2	5.71	5.83
80	3.2	6.72	6.89
100	3.6	9.75	10.0

*W.T.: wall thickness, Mass-1: mass of plain end, Mass-2: mass of screwed end with a socket, for BS 1387 light series steel tubes.

DN	NPS	O.D. max. mm	O.D. min. mm
8	1/4	13.9	13.3
10	3/8	17.4	16.8
15	1/2	21.7	21.2
20	3/4	27.2	26.6
25	1	34.2	33.4
32	1-1/4	42.9	42.1
40	1-1/2	48.4	48.0
50	2	60.8	59.8
65	2-1/2	76.6	75.4
80	3	89.5	88.1
100	4	114.9	113.3
125	5	140.6	138.7
150	6	166.1	164.1

*Maximum & minimum outside diameter of BS 1387 medium duty steel tubes.

DN	W.T. mm	Mass-3 kg/m	Mass-4 kg/m
8	2.3	0.641	0.645
10	2.3	0.839	0.845
15	2.6	1.21	1.22
20	2.6	1.56	1.57
25	3.2	2.41	2.43
32	3.2	3.10	3.13
40	3.2	3.57	3.61
50	3.6	5.03	5.10
65	3.6	6.43	6.55
80	4.0	8.37	8.54
100	4.5	12.2	12.5
125	5.0	16.6	17.1
150	5.0	19.7	20.3

*W.T.: wall thickness, Mass-3: mass of plain end, Mass-4: mass of screwed end with a socket, for BS 1387 medium series steel tubes.

DN	NPS	O.D. max. mm	O.D. min. mm
8	1/4	13.9	13.3
10	3/8	17.4	16.8
15	1/2	21.7	21.1
20	3/4	27.2	26.6
25	1	34.2	33.4
32	1-1/4	42.9	42.1
40	1-1/2	48.8	48.0
50	2	60.8	59.8
65	2-1/2	76.6	75.4
80	3	89.5	88.1
100	4	114.9	113.3
125	5	140.6	138.7
150	6	166.1	164.1

*Maximum & minimum outside diameter of BS 1387 heavy duty steel tubes.

DN	W.T. mm	Mass-5 kg/m	Mass-6 kg/m
8	2.9	0.765	0.769
10	2.9	1.02	1.03
15	3.2	1.44	1.45
20	3.2	1.87	1.88
25	4.0	2.94	2.96
32	4.0	3.80	3.83
40	4.0	4.38	4.42
50	4.5	6.19	6.26
65	4.5	7.93	8.05
80	5.0	10.3	10.5
100	5.4	14.5	14.8
125	5.4	17.9	18.4
150	5.4	21.3	21.9

*W.T.: wall thickness, Mass-5: mass of plain end, Mass-6: mass of screwed end with a socket, for BS 1387 heavy series steel tubes.

Manufacture, Heat Treatment & H.D.G

The steel shall be produced by the electric or one of the basic oxygen processes and shall be fully killed. BS 1387 HDG steel welded tubes shall be manufactured by a longitudinal welding process. The longitudinal welding process involves preparing high-quality steel strips, forming them into cylinders, and using electric resistance welding (ERW) to create a continuous weld seam. These tubes are then sized, straightened, and cut to length. They shall be supplied in the annealed or normalized condition, the as-welded condition, or the as-welded condition with the weld zone heat treated. The tubes are then sized, straightened, and cut to length.

When BS 1387 steel welded tubes are supplied with hot-dipped galvanization coating, they shall first be thoroughly descaled, washed as necessary and then dipped in a bath of molten zinc, containing not less than 98.5% by mass of zinc, at a temperature suitable to produce a complete and uniformly adherent coating of zinc. Tubes which are to be screwed shall be hot-dip galvanized before screwing. When the zinc coating quality is required to be inspected, the HDG coated tube sample shall take the copper sulfate test.

Chemical Composition and Mechanical Properties

BS 1387 steel welded tubes shall meet the chemical composition requirements according to heat analysis: C≤0.20%; Mn≤1.20; P≤0.045%; S≤0.045%. The tensile strength shall be between 320 MPa and 460 MPa while the yield strength shall be no less than 195 MPa, with the elongation value no less than 20%.

Tests and Inspection

Visual inspection, dimensional examination, tensile test, bend test, flattening test, leak tightness test, bore test (for HDG coated tubes only).