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

2-8 Earthquake Protection
Page 48 FM Global Property Loss Prevention Data Sheets
• Changed the design coefficient “G” for FM Global 50-year, 250-year, and 500-year zones (Section
2.2.1.2.2).
• Modified information on attachments to concrete in Section 2.2.1.3.6.
• Added flexibility guidelines for unanchored suction tanks (Section 2.2.6.1.4).
• Added Section 2.3 regarding the use of other standards.
• Added references in Section 4.0.
• Added glossary terms to Appendix A.
• Relocated commentary to Appendix C.
• Updated Figs. 2-6, 8, 10, 12, 14-16, and 18-29.
• Revised brace capacities (Tables 2-7), wood through-bolt and lag-screw capacities (Tables 9-12) and
concrete anchor capacities (Tables 13 and 14).
• Made minor revisions to Tables 1, 8, and 15-19.
January 2001. This revision of the document has been reorganized to provide a consistent format.
The following major changes apply to May 1999 edition:
1. In certain cases, single diagonal sway bracing is now accepted without the need to address the net vertical
uplift force component resulting from the horizontal seismic load. When the single brace angle from the
vertical is such that one-half the weight of the piping within the zone of influence for that brace equals or
exceeds the net vertical uplift force component, a single diagonal sway brace will suffice. For a “G” factor of
0.5, sway brace angles of 45 degrees or more from the vertical will qualify for this approach. For higher “G”
factors, correspondingly higher sway brace angles from the vertical will be needed.
2. Tension-only sway bracing using brace members with an l/r = 300 or less is now accepted. In those cases
two opposing diagonal braces are needed, and additionally, a vertical brace is needed to resist any net
vertical uplift force component resulting from the horizontal seismic load.
3. Revised guidelines are provided for sway bracing for branch lines 2- 1 ⁄ 2 in. (65 mm) and larger. Previously,
sway bracing was recommended only for these branch lines on gridded sprinkler systems. Now, sway bracing
is needed for 2- 1 ⁄ 2 in. (65 mm) and larger branch lines on all types of systems. These revised guidelines
will apply to any branch lines or portion of branch lines that exceed 20 ft (6.1 m) in length for lateral sway
bracing, and 25 ft (7.6 m) in length for longitudinal sway bracing.
4. A reference to “C” and “Z” purlins has been added in Section 2.2.1.1.2, Step 4 to clarify that these structural
members also need to be evaluated for acceptability as attachment points for sway bracing.
5. Additional guidance has been provided in Sections 2.2.1.2.2 and 2.2.1.2.3 to clarify the use of flexible
couplings in multistory buildings or where piping passes through walls in relation to whether proper clearances
are provided.
6. Section 2.2.1.4.8 has been revised to clarify that piping passing between two buildings that are not attached
also needs a seismic separation assembly.
7. Section 2.2.1.4.1 has been revised to delete the recommendation for anchorage of riser stubs to
underground elbows.
8. Section 2.2.1.6.1, item 4, has been revised to disallow the use of c-clamp hangers on purlins with upward
lips.
9. Section 2.2.1.7 has been revised; it recommends against the use of non-metallic pipe in aboveground
installations.
10. Section 5.2.2 is added to provide guidance for determining loss expectancies for water damage in
multi-story buildings.
11. Tables C-5.2(a) through (d) have been simplified by clearly focusing on each deficiency for determining
scenarios.
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