Process Loads in Industrial Buildings

[BAGW]

Hi,

I am designing an Industrial Building with truss roof systems. There are pipes hung from the trusses and these make up the process loads. Should these loads be treated as dead load or live load? Does any part of the code talks about this?

Thanks

 

[DaveAtkins]

I would say this is dead load.

DaveAtkins

 

[BAGW]

@ DaveAtkins

These pipes can move around. They might pull the pipe off from an area and fix it somewhere else later in the day. So shouldn't this be a Live Load? I am trying to look through the codes if I can find anything, but no luck.

 

[dik]

Take maximum pipe load, pipe plus fluid x tributary length and apply one (or two or three) of these to any location on the joist and make that part of the design criteria. I do the same for PEMB's for both the purlins and the arches.

Dik

 

[TehMightyEngineer]

I would consider it a live load; industrial buildings will often adjust piping without regard for structural capacity. Or, if they do look at the capacity they'll be much happier with the added flexibility.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

http://www.americanconcrete.com

 

[Once20036]

I consider them to be a dead load. There are no dynamic effects or movement, and the load of an individual pipe is well defined.
I agree that the flexibility Teh mentions is important, but I provide that flexibility by applying a load (5psf, for example) across the entire building. If you want more flexibility, use a higher load, rather than a higher load factor.

 

[TehMightyEngineer]

My justification for including it in the live load is that it's similar to movable partitions for an office building; the load from movable partitions are relatively easy to nail down but their location and any associated effects are not. Thus, they're moved into a live load. However, partition loads are not required when you have a 80 PSF floor live load. I would imagine you could justify a similar exemption for a heavy capacity industrial floor where the likelihood of extreme piping loads combined with extreme floor loads are somewhat unlikely.

You could just make this all a moot point by using ASD and then it doesn't generally matter if it's dead or live load.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

http://www.americanconcrete.com

 

[SlideRuleEra]

If the pipes may be hydro tested for leaks, include the weight of the water used for testing in the piping load. This could be significant if the pipes are large and carry only a gas as part of the process. Also include the weight of any insulation (often calcium silicate) and metal lagging covering it.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[Leftwow]

I use the loads from the piping as a dead load, however If your piping is encountering wind... it is standard practice to use wind on empty pipe, and wind on full pipe.

Also, you normally will have pipe stress engineers who will tell you if pipe friction needs to be considered. If there is only a few hundred lbs of Force on the structure then no you will not need to consider it. If there is a couple thousand lbs of friction then you will be considering it. This also depends on the size of the piping because if you are supporting a 2" pipe you won't get a lot of normal force to create friction. Anything over an 8 inch pipe should have stress ran on the pipe and friction considered. Some small pipe supports will have a material that's friction factor is lower than ice skates on a skating rink. Pretty interesting that they can create a material that is practically frictionless. Of course that would have to be specified by mechanical and piping engineers.

As far as themighty, I agree that there would be some live load involved but should be negligible on small pipe supports, but on large pipe racks live load should be considered because of the fact of there will be people changing out pipe. If you are designing a large pipe rack, check out the structural requirements in the PIP structural criteria, it will tell you exactly what you need.

 

[BUGGAR]

Call them collateral loads and further define them as live or dead as necessary. One size may not fit all. You can get fancy and specify your own ASD/LRFD factors if you want (we do this for Navy work - it's not a NAVFAC Standard but it works well for unusual loads and conditions).

 

[WARose]

Definitely call it dead loads. For process buildings (and I've designed a bunch), I typically go with 100 psf (+equipment). But to be sure I'm not underestimating any uplift.....I typically have a minimal dead load case with about 20-40 psf.

I'd get with your piping group. You never know what they have in mind.

 

[JStephen]

Note that not all loads fit into the normal categories- see Buggar's post. But for example, if you consider the pipe and contents as dead load, then you're using the contents of the pipe to resist uplift in the building, and assuming the pipe will always be there and always be full, which is not necessarily a realistic assumption.