G.I. Pipe is available as per IS : 1239.

DIMENSIONS OF GALVANISED STEEL TUBES AS PER IS : 1239 [PART1] / 1990
NOMINAL	CLASS	OUTSIDE DIAMETER		WALL THICKNESS		PLAIN ENDS		SCREWED AND SOCKETED
BORE (NBmm inches	abs	MINmm	MAmm	mm	SWG	Kg / Mtr	Mtrs / Tonne	Kg / Mtr	Mtrs / Tonne
15 (1/2")	L	21	21.4	2	14	0.947	1056	0.956	1046
	M	21	21.8	2.6	12	1.21	826	1.22	820
	H	21	21.8	3.2	10	1.44	694	1.45	690
20 (3/4")	L	26.4	26.9	2.3	13	1.38	725	1.39	719
	M	26.5	27.3	2.6	12	1.56	641	1.57	637
	H	26.5	27.3	3.2	10	1.87	535	1.88	532
25 (1")	L	33.2	33.8	2.6	12	1.98	505	2	500
	M	33.3	34.2	3.2	10	2.41	415	2.43	412
	H	33.3	34.2	4	8	2.93	341	2.95	339
32 (11/4")	L	41.9	42.5	2.6	12	2.54	394	2.57	389
	M	42	42.9	3.2	10	3.1	325	3.13	319
	H	42	42.9	4	8	3.79	264	3.82	262
40 (11/2")	L	47.8	48.4	2.9	11	3.23	310	3.27	306
	M	47.9	48.8	3.2	10	3.56	281	3.6	278
	H	47.9	48.8	4	8	4.37	229	4.41	227
50 (2")	L	59.6	60.2	2.9	11	4.08	245	4.15	241
	M	59.7	60.8	3.6	9	5.03	199	5.1	196
	H	59.7	60.8	4.5	7	6.19	162	6.26	160
65 (21/2")	L	75.2	76	3.2	10	5.71	175	5.83	172
	M	75.3	76.6	3.6	9	6.42	156	6.54	153
	H	75.3	76.6	4.5	7	7.93	126	8.05	124
80 (3")	L	87.9	88.7	3.2	10	6.72	149	6.89	145
	M	88	89.5	4	8	8.36	120	8.53	117
	H	88	89.5	4.8	6	9.9	101	10.4	96
100 (4")	L	113	113.9	3.6	9	9.75	103	10	100
	M	113.1	115	4.5	7	12.2	82	12.5	80
	H	113.1	115	5.4	5	14.5	69	14.8	68
125 (5")	M	138.5	140.8	4.8	6	15.9	63	16.4	61
	H	138.5	140.8	5.4	5	17.9	56	18.4	54
150 (6")	M	163.9	166.5	4.8	6	18.9	53	19.5	51
	H	163.9	166.5	5.4	5	21.3	47	21.9	46

Tolerances     Thickness :   Light tubes   : Not Limited   : - 8%   Medium & Heavy Tubes   : + Not Limited   : - 10%   Weight :   1. Single tube (Light Series)   : +10% - 8%   2. Single tube (Medium & Heavy Series)   : + - 10%   3. For quantities perload of 10 tonnes min (light Series)   : + - 5%   4. For quantities perload of 10 tonnes min. (Medium & Heavy Series)   : + - 7.5%   Length :   Light, Medium & Heavy tubes   : Random Length of 4 to 7 meters unless specified otherwise