38
CVHE-SVX005C-EN
Table 11. Flange screw torque recommendations for
O-ring and flat-gasket piping connections
Screw Size
Gasket Type
O-Ring
Flat
in. mm ft·lb N·m ft·lb N·m
3/8 9.5 25 34 12–18 16–24
1/2 13 70 95 33–50 45–68
5/8 16 150 203 70–90 95–122
3/4 19 250 339 105–155 142–210
Note: Screw size is determined by the diameter of the screw shank.
Flanges with 4, 8, or 12 Screws
Tighten all screws to a snug tightness, following the
numerical sequence for the appropriate pattern as shown
in the following figure. Repeat this sequence to apply the
final torque to each screw.
Figure 20. Flange screw tightening sequence (4, 8, or
12 screws)
1 3
4 2
1
3
4 5
7
8
2 6
1
3
4
10 11
9
5
7
8
12
26
4 screws 8 screws
12 screws
Flanges with 16, 20, or 24 Screws
Tighten only the first half of the total number of screws to a
snug tightness, following the numerical sequence for the
appropriate pattern as shown in the following figure. Next,
sequentially tighten the remaining half of the screws in
numerical order.
Figure 21. Flange screw tightening sequence (16, 20,
or 24 screws)
16 screws 20 screws
24 screws
1
5
9
20
2
3
4
6
7
8
10
19
18
17
16
15
14
13
12
11
1
24
5
9
20
2
23
3
4
22
6
7
8
10
19
18
17
21
16
15
14
13
12
11
1
5
9
2
3
4
6
7
8
10
16
15
14
13
12
11
Flanges with More than 24 Screws
Sequentially tighten the first 12 screws to a snug tightness,
following the numerical sequence as shown in the following
figure. Tighten the next 12 consecutively numbered screws
in sequence to the final torque. Then, apply final torque to
the first 12 screws and the screws not yet tightened (i.e.,
unnumbered screws in the following figure). Start with
screw “1” and move progressively around the flange in a
clockwise direction.
Figure 22. Flange screw tightening sequence (more
than 24 screws)
1
24
5
9
20
2
23
3
4
22
6
7
8
10
19
18
17
21
16
15
14
13
12
11
Evaporator Waterbox Covers
Ensure that the waterbox head rests tightly against the
tube sheet, and then snugly tighten the 26 bolts in
Installation: Water Piping
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