U Bolts BS 3974

U-bolts, hook bolts and overstraps shail be of the types detailed below and illustrated in Figure 1 and Figure 2 respectively.
1) U-bolt (not to grip the pipe), required where it is undestrable to restrict longitudinal movement (see Figure 1)
2) U-bolt (to grip the pipe),required where it is necessary to hold the pipe in all directions (see Figure 2)
3) Hook bolt, required where it is necessary to steady the pipe (see Figure 3)
Dimensions.The dimensions of U-bolts (not to grip the pipe) shall be in accordance with those given in Table 10. The dimensions of U bolts (to grip the pipe) and of hook bolts shall be in accordance with those given in Table 11

Dimensions of U-bolts (not to grip pipe)

Steel pipes
Nominal Pipe Size	Pipe o.d.	A dia.	N	M	K	S max.
15	21.3	8	40	45	25	10
20	26.9	8	45	55	30	10
25	33.7	8	50	60	30	10
32	42.4	8	60	70	30	16
40	48.3	10	65	85	40	16
50	60.3	10	80	100	40	16
65	76.1	12	95	120	50	19
80	88.9	16	110	140	55	19
100	114.3	16	140	165	55	19
125	139.7	16	165	190	55	19
150	168.3	20	195	225	65	19
175	193.7	20	220	250	65	19
200	219.1	20	250	275	65	19
225	244.5	20	275	300	65	19
250	273.0	20	305	335	75	22
300	323.9	20	355	385	75	22
350	355.6	24	390	425	80	22
400	406.4	24	440	475	80	22
450	457.0	24	495	525	80	22
500	508.0	24	545	575	80	22
550	559.5	24	595	625	80	22
600	610.0	24	645	675	80	22
Cast iron pipes
80	98	16	120	150	55	19
^a100	118	16	140	165	55	19
^a150	170	20	195	225	65	19
^a200	222	20	250	275	65	19
^a250	274	20	305	335	75	22
^a300	326	20	355	385	75	22
350	378	24	410	450	80	22
400	429	24	465	500	80	22
450	480	24	520	550	80	22
500	532	24	570	600	80	22
600	635	24	670	700	80	22
^aThese U-bolts are identical with the equivalent sizes for steel pipe.

Dimensions of points for metric socket set screws

Steel pipes
Nominal Pipe Size	Pipe o.d.	A dia.	N	M	K	S max.
15	21.3	8	30	50	25	7
20	26.9	8	35	60	25	10
25	33.7	8	45	65	25	10
32	42.4	8	55	75	25	10
40	48.3	10	60	90	35	16
50	60.3	10	75	100	35	16
65	76.1	12	90	130	45	19
80	88.9	16	105	150	50	19
100	114.3	16	135	175	50	19
125	139.7	16	160	200	50	19
150	168.3	20	190	235	55	19
175	193.7	20	215	260	55	19
200	219.1	20	245	295	55	19
225	244.5	20	270	310	55	19
250	273.0	20	300	350	60	22
300	323.9	20	350	400	60	22
350	355.6	24	385	440	65	22
400	406.4	24	435	500	65	22
450	457.0	24	485	540	70	22
500	508.0	24	540	600	70	22
550	559.5	24	590	650	70	22
600	610.0	24	640	700	70	22
Cast iron pipes
80	98	16	115	160	50	19
^a100	118	16	135	175	50	19
^a150	170	20	190	235	55	19
^a200	222	20	245	295	55	19
^a250	274	20	300	350	60	22
^a300	326	20	350	400	60	22
350	378	24	405	460	65	22
400	429	24	455	520	65	22
450	480	24	505	560	70	22
500	532	24	560	620	70	22
600	635	24	660	720	70	22
^aThese U-bolts and hook bolts are identical with the equivalent sizes for steel pipe.

ASTM A193 Grade B87 Specifications

U-bolts, hook bolts and overstraps

Dimensions of U-bolts (not to grip pipe)

Dimensions of points for metric socket set screws

ASTM A193 Grade B8C Fastener Coatings