Location of Hangers on mains

[eatapeach]

I can't find anywhere in the NFPA 13 that addresses the hanger locations at bends or change in directions. Are supports not required within a certain distance of a change of direction? All I see in NFPA 13 for 4" steel pipe is every 15'. I am in a seismic category B so 9.4 doesn't apply. I also was searching for a maximum length allowed for 3/8" threaded rod supporting steel pipe. I have seen stiffeners on threaded rod before but I cant find where its called out to be of a certain length before installing them. Can anyone help with these two questions.
Thanks

 

[TravisMack]

Seismic bracing is required at changes in direction. There is nothing about hangers being required at a change in direction. You just have to adhere to the distances, but there shall be a hanger on each section of pipe or between branch lines.

There is nothing I can see about the maximum length of 3/8" rod.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com