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18.5.1 General
18.5.1.1
The system piping shall be braced to resist both lateral and longitudinal horizontal seismic loads and to prevent vertical motion resulting from seismic loads.
18.5.1.2
The structural components to which bracing is attached shall be determined to be capable of resisting the added applied seismic loads.
18.5.1.3*
Horizontal loads on system piping shall be determined in accordance with 18.5.9.
18.5.1.4*
A shared support structure shall be permitted to support both the gravity loads addressed in 17.1.4.1 and the seismic loads addressed in 18.5.9.
18.5.1.4.1
When a shared support structure is used to support gravity and seismic loads, the structure shall be designed to support these loads for all pipe and distribution systems on the structure using either 18.5.9.3 or 18.5.9.4 with an importance factor, Ip, of 1.5 being applied to all of the distribution systems.
18.5.1.5*
If a shared support structure is used to support sprinkler pipe and other distribution systems per 17.1.4.1 and that structure does not provide seismic resistance as required in 18.5.1.4, the following shall be met:
  1. The sprinkler pipe shall be braced using the method in 18.5.6 with the zone of influence including the water-filled sprinkler pipe and all other distribution systems that are not independently equipped with seismic protection and attached to the shared support structure.
  2. The sprinkler sway bracing attachment shall be connected to the same building or structure as the shared support structure.
18.5.1.6
Bracing requirements of Section 18.5 shall not apply to drain piping downstream of the drain valve.
18.5.2 Listing
18.5.2.1
Sway bracing assemblies shall be listed for a maximum load rating, unless the requirements of 18.5.2.2 are met.
18.5.2.2
Where sway bracing utilizing pipe, angles, flats, or rods as shown in Table 18.5.11.8(a) through Table 18.5.11.8(f) is used, the components shall not require listing.
18.5.2.2.1
Bracing fittings and connections used with those specific materials shall be listed.
18.5.2.3*
The listed load rating shall be reduced as shown in Table 18.5.2.3 to determine the allowable load for installations where the brace is less than 90 degrees from vertical.
Table 18.5.2.3 Listed Horizontal Load Adjustment
Brace Angle Degrees from Vertical Allowable Horizontal Load
30 to 44 Listed load rating divided by 2.000
45 to 59 Listed load rating divided by 1.414
60 to 89 Listed load rating divided by 1.155
90 Listed load rating
18.5.2.3.1*
Maximum allowable horizontal loads shall be determined by testing at angles of 30, 45, 60, and 90 degrees from vertical and confirmed to be equal to or greater than those calculated using 18.5.2.3.
18.5.2.3.2
For attachments to structures, additional tests shall be performed at 0 degrees.
18.5.3 Component Material
18.5.3.1
Unless permitted by 18.5.3.2, components of sway brace assemblies shall be ferrous.
18.5.3.2
Nonferrous components that have been proven by fire tests to be adequate for the hazard application, that are listed for this purpose, and that are in compliance with the other requirements of this section shall be acceptable.
18.5.4 Sway Bracing Design
18.5.4.1
Sway braces shall be designed to withstand forces in tension and compression, unless the requirements of 18.5.4.2 are met.
18.5.4.2*
Tension-only bracing systems shall be permitted for use where listed for this service and where installed in accordance with their listing limitations, including installation instructions.
18.5.4.3
For all braces, whether or not listed, the maximum allowable load shall be based on the weakest component of the brace with safety factors.
18.5.5 Lateral Sway Bracing
18.5.5.1*
Lateral sway bracing shall be provided on all feed and cross mains regardless of size and all branch lines and other piping with a diameter of 21/2 in. (65 mm) and larger.
18.5.5.1.1
Where branch lines are not provided with lateral sway bracing, they shall be provided with restraint in accordance with Section 18.6.
18.5.5.2*
The spacing between lateral sway braces shall be in accordance with either Table 18.5.5.2(a) through Table 18.5.5.2(l) or 18.5.5.3, based on the piping material of the sprinkler system.
Table 18.5.5.2(a) Maximum Load (Fpw) in Zone of Influence (lb), (Fy = 30 ksi) Schedule 10 Steel Pipe
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (ft)
20 25 30 35 40
1 111 89 73 63 52
11/4 176 141 116 99 83
11/2 241 193 158 136 114
2 390 312 256 219 183
21/2 641 513 420 360 301
3 966 773 633 543 454
31/2 1281 1025 840 720 603
4 1634 1307 1071 918 769
5 2814 2251 1844 1581 1324
6 and larger* 4039 3231 2647 2269 1900
Note: ASTM A106 Grade B or ASTM A53 Grade B has an Fy = 35 ksi. An Fy = 30 ksi was used as a conservative value to account for differences in material properties as well as other operational stresses.
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(b) Maximum Load (Fpw) in Zone of Influence (kg), (Fy = 207 N/mm2) Schedule 10 Steel Pipe
Diameter of Pipe (mm) Being Braced Lateral Sway Brace Spacing (m)
6.1 7.6 9.1 11 12
25 50 40 33 29 24
32 80 64 53 45 38
40 109 88 72 62 52
50 177 142 116 99 83
65 291 233 191 163 137
80 438 351 287 246 206
90 581 465 381 327 273
100 741 593 486 416 349
125 1276 1021 836 717 601
150* 1832 1466 1201 1029 862
Note: ASTM A106 Grade B or ASTM A53 Grade B has an Fy = 241 N/mm2. An Fy = 207 N/mm2 was used also as a conservative value to account for differences in material properties as well as other operational stresses.
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(c) Maximum Load (Fpw) in Zone of Influence (lb), (Fy = 30 ksi) Schedule 40 Steel Pipe
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (ft)
20 25 30 35 40
1 121 97 79 68 57
11/4 214 171 140 120 100
11/2 306 245 201 172 144
2 520 416 341 292 245
21/2 984 787 645 553 463
3 1597 1278 1047 897 751
31/2 2219 1775 1455 1247 1044
4 2981 2385 1954 1675 1402
5 5061 4049 3317 2843 2381
6 and larger* 7893 6314 5173 4434 3713
Note: ASTM A106 Grade B or ASTM A53 Grade B has an Fy = 35 ksi. An Fy = 30 ksi was used as a conservative value to account for differences in material properties as well as other operational stresses.
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(d) Maximum Load (Fpw) in Zone of Influence (kg), (Fy = 207 N/mm2) Schedule 40 Steel Pipe
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (m)
6.1 7.6 9.1 11 12
25 55 44 36 31 26
32 97 78 63 54 45
40 139 111 91 78 65
50 236 189 155 132 111
65 446 357 293 251 210
80 724 580 475 407 341
90 1007 805 660 566 474
100 1352 1082 886 760 636
125 2296 1837 1505 1290 1080
150* 3580 2864 2346 2011 1684
Note: ASTM A106 Grade B or ASTM A53 Grade B has an Fy = 241 N/mm2. An Fy = 207 N/mm2 was used also as a conservative value to account for differences in material properties as well as other operational stresses.
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(e) Maximum Load (Fpw) in Zone of Influence (lb), (Fy = 30 ksi) Schedule 5 Steel Pipe
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (ft)
20 25 30 35 40
1 71 56 46 40 33
11/4 116 93 76 65 55
11/2 154 124 101 87 73
2 246 197 161 138 116
21/2 459 367 301 258 216
3 691 552 453 388 325
31/2 910 728 597 511 428
4* 1160 928 760 652 546
Note: ASTM A106 Grade B or ASTM A53 Grade B has an Fy = 35 ksi. An Fy = 30 ksi was used as a conservative value to account for differences in material properties as well as other operational stresses.
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(f) Maximum Load (Fpw) in Zone of Influence (kg), (Fy = 207 N/mm2) Schedule 5 Steel Pipe
Diameter of Pipe (mm) Being Braced Lateral Sway Brace Spacing (m)
6.1 7.6 9.1 11 12
25 32 25 21 18 15
32 53 42 34 29 25
40 70 56 46 39 33
50 112 89 73 63 53
65 208 166 137 117 98
80 313 250 205 176 147
90 413 330 271 232 194
100* 526 421 345 296 248
Note: ASTM A106 Grade B or ASTM A53 Grade B has an Fy = 241 N/mm2. An Fy = 207 N/mm2 was used also as a conservative value to account for differences in material properties as well as other operational stresses.
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(g) Maximum Load (Fpw) in Zone of Influence (lb), (Fy = 8 ksi) CPVC Pipe
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (ft)
20 25 30 35 40
3/4 15 12 10 8 7
1 28 22 18 15 13
11/4 56 45 37 30 26
11/2 83 67 55 45 39
2 161 129 105 87 76
21/2 286 229 188 154 135
3 516 413 338 278 243
Table 18.5.5.2(h) Maximum Load (Fpw) in Zone of Influence (kg), (Fy = 55 N/mm2) CPVC Pipe
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (m)
6.1 7.6 9.1 11 12
20 7 5 5 4 3
25 13 10 8 7 6
32 25 20 17 14 12
40 38 30 25 20 18
50 73 59 48 39 34
65 130 104 85 70 61
80 234 187 153 126 110
Table 18.5.5.2(i) Maximum Load (Fpw) in Zone of Influence (lb), (Fy = 30 ksi) Type M Copper Tube (with Soldered Joints)
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (ft)
20 25 30 35 40
3/4 16 13 10 9 8
1 29 24 19 16 14
11/4 53 42 35 28 25
11/2 86 69 56 46 41
2* 180 144 118 97 85
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(j) Maximum Load (Fpw) in Zone of Influence (kg), (Fy = 3207 N/mm2) Type M Copper Tube (with Soldered Joints)
Diameter of Pipe (in.) Being Braced Lateral Sway Brace Spacing (m)
6.1 7.6 9.1 11 12
20 7.3 5.9 5 4.1 3.6
25 13.2 10.9 8.6 7.3 6.4
32 24 19.1 15.9 12.7 11.3
40 39 31.3 25.4 20.9 18.6
50* 81.6 65.3 53 44 38.6
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(k) Maximum Load (Fpw) in Zone of Influence (lb), (Fy = 9 ksi) Type M Copper Tube (with Brazed Joints)
Diameter of Pipe (in.) Being Braced Lateral Sway Spacing (ft)
20 25 30 35 40
3/4 6 5 4 3 3
1 11 9 7 6 5
11/4 20 16 13 12 10
11/2 33 27 22 19 16
2* 70 56 46 39 33
*Larger diameter pipe can be used when justified by engineering analysis.
Table 18.5.5.2(l) Maximum Load (Fpw) in Zone of Influence (lb), (Fy = 9 ksi) Red Brass Pipe (with Brazed Joints)
Diameter of Pipe (in.) Being Braced Lateral Sway Spacing (ft)
20 25 30 35 40
3/4 34 27 22 19 16
1 61 49 40 35 29
11/4 116 93 76 65 55
11/2 161 129 105 90 76
2* 272 218 178 153 128
*Larger diameter pipe can be used when justified by engineering analysis.
18.5.5.2.1
Specially listed nonstandard pipe shall be permitted using the values in Table 18.5.5.2(e) and Table 18.5.5.2(f) or with values provided by the manufacturer.
18.5.5.2.2
Spacing shall not exceed a maximum interval of 40 ft (12 m) on center.
18.5.5.2.3
The maximum permissible load in the zone of influence of a sway brace shall not exceed the values given in Table 18.5.5.2(a) through Table 18.5.5.2(1) or the values calculated in accordance with 18.5.5.3.
18.5.5.2.4
When determining permissible loads in accordance with 18.5.5.2 or 18.5.5.2.1 on a main with varying sizes, the allowable load shall be based on the smallest pipe size within the zone of influence.
18.5.5.3
The maximum load (Fpw) in the zone of influence for specially listed pipe shall be calculated. (See Annex E.)
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