Allan, I think the unistrut problem orobably arises from the unistrut two piece strap not being listed. We just used the the short strap as shown in 13/2007 figure a 9.1.1--common types of acceptable hangers. If it's in the book the AHJ in question will buy it. This is a guy that wouldn't accept hand calcs because he can't trust the math but will accept any computer calc even if my monkey entered the data (he can't read these either). Unfortunately he prefers to mask his inadequacies by being the hardcore petty bureaucrat rather than working with people trying to work with him. Personally I think that this is pretty simple. Since we rely on standard hangers to thwart gravity and on bracing to conform with inertia then a pipe on the floor (or a block that's on the floor) takes care of the gravity part. Standard bracing then ought to conform with inertia. The problem then is finding adequate structure at the floor level. In the case of concrete you just need to run standard calcs against your bracing configuration. I think you may be over engineering this problem but please feel free to point out where my ideas fall short. I tend to look for simple solutions and sometimes under think things through.
On Mon, Jun 9, 2008 at 6:37 PM, Allan Seidel <[EMAIL PROTECTED]> wrote: > Thanks Ron. This is exactly the type of information I am looking for. In > this case the supports have to be engineered but it would be nice to defend > as few broken rules as possible. The spacing is 10 feet and 5 feet, so the > loads are low and the preliminary back of envelope stress numbers look just > fine, even for seismic. If push comes to shove we'll have one mocked up to a > 350 pound block and pick it up with a backhoe, though I am not sure the 250 > added load makes sense when the pipe sits on top of the beam. > > I am curious what strap was "listed" if it is a strap for unistrut? > > Thanks, > Allan Seidel > St. Louis, MO > > On Jun 7, 2008, at 2:17 PM, Ron Greenman wrote: > >> Allan, >> >> I just ran into this and was surprised. Typically what I've seen is >> drop-in anchor or red-head holding down the strut then a strut clamp >> for the pipe. Had an AHJ recently say that strut wasn't listed and low >> and behold it's not. you'll find a table that gives values in the case >> of trapeze so that you can calculate the material in accordance with >> 13 for trapezes but that's it. What we did was use a drop-in then a >> rodded up through the strut, through the holes of a pipe strap and >> then captured the strut and strap with a nut. This was OK to the AHJ >> since the strap was listed and the strut was merely a block. I >> suppose we could have used a treated 2x4 or one of those rubber blocks >> the plumbers used for the stand-off and done just as well or better. >> In fact there's a job with pipe on the roof that we plan on using the >> rubber blocks on. I'd check with your AHJ to see what he'll allow. >> This guy we had through me. Hope this helps. >> >> On Sat, Jun 7, 2008 at 10:28 AM, Allan Seidel <[EMAIL PROTECTED]> wrote: >>> >>> A sprinkler system, both mains and branch lines, will be supported >>> entirely >>> from below. There will be no hangers and supports will occur at least >>> every >>> ten feet. NFPA 13 does not seem to address this condition in any detail. >>> I >>> can think of many ways to support and anchor the piping. The problem is I >>> need to know what methods are not permitted. For example, is piping >>> strapped >>> to a unistrut, point-load style, technically not permitted? >>> >>> Thank you, >>> Allan Seidel >>> St. Louis, MO >>> _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >>> >>> To Unsubscribe, send an email to:[EMAIL PROTECTED] >>> (Put the word unsubscribe in the subject field) >>> >> >> >> >> -- >> Ron Greenman >> at home.... >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >> >> To Unsubscribe, send an email to:[EMAIL PROTECTED] >> (Put the word unsubscribe in the subject field) > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > > To Unsubscribe, send an email to:[EMAIL PROTECTED] > (Put the word unsubscribe in the subject field) > -- Ron Greenman at home.... _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
