DS 2-8 Earthquake Protection for Water-Based Fire ... - FM Global

2-8 Earthquake Protection
Page 4 FM Global Property Loss Prevention Data Sheets
2. The omission of even a few of the critical components necessary for adequate earthquake
protection may result in impairment of the system or substantial water damage. The necessary
shutdown of the system to stop further water damage also creates a long-term fire protection
system impairment.
The recommendations in this data sheet are intended to: (1) greatly improve the likelihood that the fire
protection system(s) will remain in working condition after the earthquake, and (2) minimize potential water
damage from fire protection system leakage. For each type of fire protection system described in the
following sections, completion of all recommendations will maximize the probability of the system performing
as intended during an earthquake.
In general, recommendations are related to the following seven goals:
1. Bracing piping and equipment to minimize uncontrolled differential movement between these items
and the structure(s) to which they are attached.
2. Providing flexibility on piping systems and on other equipment where differential movement between
portions of those piping systems or equipment is expected. Except where large differential movement
occurs over a short distance, flexible couplings provide sufficient flexibility between portions of sprinkler
piping systems where needed.
3. Providing clearance between piping or equipment and structural members, walls, floors, or other objects
so that potential damage from impact is minimized.
4. Providing anchorage to minimize potential sliding and/or overturning.
5. Using appropriate types of pipe hangers and sway bracing, properly located and attached to the structure
to minimize the potential for pullout.
6. Using appropriate types of piping and pipe-joining methods to minimize potential pipe breaks.
7. Providing fire protection system plans and calculations with proper verification of design, and proper
verification that the completed installation is in accordance with the design as well as good installation
practices.
NOTE: See Section 2.3 for guidance on using other codes and standards to provide earthquake
protection of fire protection systems similar to that recommended in this data sheet.
2.2 Protection
2.2.1 Sprinkler Systems, Including In-Rack Sprinkler Systems and Small-Hose Piping Systems
2.2.1.1 Sway Bracing Locations
2.2.1.1.1 Lay out sway bracing locations (a) per Sections 2.2.1.1.2 through 2.2.1.1.5, unless closer spacing
is needed based on brace or attachment capacity limits, and (b) so that sway bracing locations will coincide
with the structural members to which the sway braces will be attached.
2.2.1.1.2 Brace all sprinkler system risers whether they are single or manifolded type, and regardless of size,
in accordance with the following guidelines.
A. Provide a four-way sway brace within 2 ft (0.6 m) of the top of the riser as shown in Fig. 1. For risers
located on the outside of the building, either Detail A or B of Fig. 1 may be used, with the brace attached
to a structural element. When possible, avoid the use of manifolded sway bracing at the top of multiple
adjacent risers. If used, limit the manifolded arrangement to two risers, and design bracing to carry the
total loads for both risers.
B. Provide intermediate four-way sway bracing at an interval not to exceed 40 ft (12.2 m). Where flexible
couplings are used, arrange this intermediate four-way sway bracing so a brace is provided within 2 ft
(0.6 m) of every other flexible coupling (adding four-way braces if necessary). In multistory buildings, lay
out bracing so a four-way brace is provided at each floor having a supply main; a four-way brace is
considered to exist when the riser passes through a structural floor, and clearances do not exceed the
minimums per Section 2.2.1.5.1.
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