Contents - Bufab

Tightening torques and forces for Bumax unions
Table 9
Pitch
of thread
Nominal stress
area mm2 Tightening torque M v , Nm / Ibf.ft 1), 3) Preload applied KN / Ibf ± 23% 2) Failure load KN Yield load KN
Lock 88
KN Ibf 109 88 Lock 88 109 88 Lock 88
88
KN Ibf
109
KN Ibf
Lock 88
Nm Ibf.ft
88
Nm Ibf.ft
109
Nm Ibf.ft
dim/class,
Bumax
0.5
0.7
0.8
1.0
1.25
5.03
8.78
14.2
20.1
36.6
3.2
6
9
13
23
3.2
6
9
13
23
4.5
8
13
18
33
4
7
11
16
29
4
7
11
16
29
5
8.8
14
20
37
472
809
1326
1888
3372
2.1
3.6
5.9
8.4
15
472
809
1326
1888
3372
2.1
3.6
5.9
8.4
15
652
3.6
1933
2698
4721
2.9
5.2
8.6
12
21
-
-
4.9
8.9
21.4
-
-
6.6
12
29
0.96
2.1
4.2
7.4
18.4
1.3
2.9
5.7
10
25
1.25
3
6
10.3
25
1.7
4.2
8.1
14
34
M3
M4
M5
M6
M8
1.5
1.75
2.0
2.0
2.0
2.5
58.0
84.3
115
157
192
245
37
54
74
100
123
157
37
54
74
100
123
157
52
76
92
125
154
196
46
67
92
126
154
196
46
67
92
126
154
196
58
84
115
157
192
245
5395
7868
10791
14613
17985
22931
24
35
48
65
80
102
5395
7668
10791
14613
17985
22931
24
35
48
65
80
102
7644
11016
13489
18210
22481
28776
34
49
60
81
100
128
39.8
69.3
-
168
-
326
54
94
-
228
-
442
34.7
60.5
95
146
203
284
47
82
129
198
275
385
48.7
84.8
62
183
254
355
66
115
162
248
344
481
M10
M12
M14
M16
M18
M20
3.0
3.0
3.5
4.0
20 th/inch
18 th/inch
16 th/inch
13 th/inch
11 th/inch
10 th/inch
9 th/inch
8 th/inch
353
459
561
817
226
294
359
523
226
294
359
523
-
-
-
-
282
367
449
654
282
367
449
654
-
-
-
-
40690
52830
64520
93970
181
235
287
418
40690
52830
64520
93970
181
235
287
418
-
-
-
-
-
-
-
-
564
-
-
-
765
-
-
-
490
709
966
1682
665
961
1310
2280
-
-
-
-
20.5
33.8
50.0
91.5
146.0
216.0
298.0
391.0
-
-
-
-
-
-
-
-
13.1
22.4
33.2
60.8
96.9
143.4
197.9
259.6
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
17.0
28.0
41.5
75.9
121.0
179.0
247.0
325.0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
8.0
13.2
19.5
35.7
56.9
84.2
116.2
152.5
1798
2967
4384
8026
12792
18929
26123
34283
8.0
13.2
19.5
35.7
56.9
84.2
116.2
152.5
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
8.1
16.2
28.8
70
139
243
389
582
11
22
39
95
188
329
527
789
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
M24
M27
M30
M36
1/4-20 UNC
5/16-18 UNC
3/8-16 UNC
1/2-13 UNC
5/8-11 UNC
3/4-10 UNC
7/8-9 UNC
1"-8 UNC
1) The tightening torque recommendations refer to fl at burr-free surfaces, lubricated with a high quality lubricant.
2) Preload applied is calculated as 65% of Rp 0.2, but in practice the value could be expected to vary between around 50% and 80% of this.
3) The tightening torque recommendations are calculated according to a co-effi cient of friction of 0.16, which is equivalent to wax BSAB 1952V.
The stress is calculated as around 70% of the yield load but could in practice be expected to vary between around 60% – 80%.
51