CPBe
Structural
- Nov 4, 2019
- 18
Looking for some input/interpretation on a somewhat vague paragraph in ASCE7 ch.13 - see excerpt below:
Suspended components that are installed in-line and rigidly
connected to and supported by the piping system, such as valves,
strainers, traps, pumps, air separators, and tanks, are permitted to
be considered part of the piping system for the purposes of
determining the need for and sizing of lateral bracing. Where
components are braced independently because of their weight but
the associated piping is not braced, flexibility shall be provided as
required to accommodate relative movement between the
components.
It's the "...because of their weight..." verbiage that creates confusion.
For a seismic design category "D" building w/risk group II piping 3" & less is exempt from seismic requirements, but a 3" in-line pump could weigh over 200 lbs; suspended non-structural components over 20 lbs require seismic bracing for D-II structures). If the pump needs to be isolated w/springs it makes sense to specify flex piping on each side of the pump & brace it independently, but if it's "...rigidly connected to & supported by the piping system..." what would be the cutoff? (sec. 13.6.6 includes a similar paragraph noting a 75 lbs weight limit for components in-line w/duct - would it make sense to adhere to the same limit? Or could/should it be scaled up for components in line w/piping systems?)
Any feedback is greatly appreciated.
Thank you in advance for your insight!
Suspended components that are installed in-line and rigidly
connected to and supported by the piping system, such as valves,
strainers, traps, pumps, air separators, and tanks, are permitted to
be considered part of the piping system for the purposes of
determining the need for and sizing of lateral bracing. Where
components are braced independently because of their weight but
the associated piping is not braced, flexibility shall be provided as
required to accommodate relative movement between the
components.
It's the "...because of their weight..." verbiage that creates confusion.
For a seismic design category "D" building w/risk group II piping 3" & less is exempt from seismic requirements, but a 3" in-line pump could weigh over 200 lbs; suspended non-structural components over 20 lbs require seismic bracing for D-II structures). If the pump needs to be isolated w/springs it makes sense to specify flex piping on each side of the pump & brace it independently, but if it's "...rigidly connected to & supported by the piping system..." what would be the cutoff? (sec. 13.6.6 includes a similar paragraph noting a 75 lbs weight limit for components in-line w/duct - would it make sense to adhere to the same limit? Or could/should it be scaled up for components in line w/piping systems?)
Any feedback is greatly appreciated.
Thank you in advance for your insight!
