British standard pipe BS 1387 : 1967 light

Nominal bore		Outside diameter				Thickness		Calculated weight of black tube
		max.	min	max.	min.			Plain End		Screwed and socketed
in	mm	in	in	mm	mm	in	mm	lb/ft	kg/m	lb/ft	kg/m
1/4	8	0.532	0.518	13.6	13.2	0.072	1.8	0.347	0.517	0.35	0.521
3/8	10	0.671	0.656	17.1	16.7	0.072	1.8	0.453	0.674	0.457	0.68
1/2	15	0.841	0.825	21.4	21	0.08	2	0.64	0.952	0.646	0.961
3/4	20	1.059	1.041	26.9	26.4	0.092	2.35	0.944	1.41	0.954	1.42
1	25	1.328	1.309	33.8	33.2	0.104	2.65	1.35	2.01	1.36	2.03
1 1/4	32	1.67	1.65	42.5	41.9	0.104	2.65	1.73	2.58	1.75	2.61
1 1/2	40	1.903	1.882	48.4	47.8	0.116	2.9	2.19	3.25	2.22	3.29
2	50	2.37	2.347	60.2	59.6	0.116	2.9	2.76	4.11	2.81	4.18
2 1/2	65	2.991	2.96	76	75.2	0.128	3.25	3.9	5.8	3.98	5.92
3	80	3.491	3.46	88.7	87.9	0.128	3.25	4.58	6.81	4.69	6.98
3 1/2	90	3.981	3.95	101.1	103.3	0.144	3.65	5.88	8.75	6	8.929
4	100	4.481	4.45	113.9	113	0.144	3.65	6.64	9.89	6.84	10.2