Seismic Bracing

[jjmoore73]

AHJ wants seismic bracing per code, but says there must be bracing within 2 feet of every 90. The old school general rule is... ends, bends and change of direction need seismic bracing. When reading through Chapter 9, I do not see where it says bracing within 2' of changes in direction. Is this an old rule or is it somewhere in the code I am not seeing.

 

[Sdpaddler50]

I dont know who this AHJ is, or standard you are applying. If you are applying FM, 2-8 requires it at 90's and changes and direction, and it has to be within 2 ft of change of direction. It has been that way for FM, for many years.

 

[TravisMack]

I know that in order for the lateral brace to act as a longitudinal brace on the adjacent pipe that you have to be within 24" of the turn. You also must be within 6' of the end of the pipe being braced.

Strictly per NFPA 13, I don't believe the 2' from a turn is required if you are not using that same brace as a longitudinal for the adjacent pipe.

However, that old method of 40/80 and 4 way at change in direction, etc... that is long gone. Braces must be calculated. You have to meet specific requirements of the bracing components and for laterals, you have to take into consideration the size and schedule of the piping.

If you have not done bracing in a long time, you may want to spend a few hours in Chap 9 getting reacquainted. It is quite different.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com