Hanger Prefabrication

[sheetmetalman]

All,

I have a question in regards to pipe/plumbing hanger prefabrication.

Our field superintendents want all hangers exact, and I mean exact.
With rods set to the exact height when they arrive on site.

Is anyone else out there doing exact length rods, and having 96-100% success ratio?

Or are you guys sending rods a little longer and having the field trim to length?

I'm seeing too many elements that can cause rod lengths to be too long, which causes the field to cut them down, and apparently that's the end of the world for them.

We are maybe at 75% on the money perfect and the others need to be cut down a little.

Thoughts?

[Axl]

We can calculate the exact rod dimension but if for some of the common issues you run short just 1" that will be the end of the world for them and your budget, one inch of rod cost nothing even by the hundreds, but hundreds of replaced rod cost way more. We add 4" to each rod in case there is last minute change, I cannot see a 100% accurate rod length working in the real world.

I would calculate what it takes to cut the rods for them at exact length and what it takes to replace all the rods in case of a last minute change and present the numbers, what ever is cheaper.

[sheetmetalman]

That is exactly what I would do if it were up to me, give them enough material to complete the job.

Agreed, rod cost is minimal.

[edsharp]

Agreed

there are a ton of variables that would lead to disaster trying to hit spot on ...i have created 2 reports  one that rounds up to the closest 6" and one that rounds up to the closest foot... we do provide hanger list to the field super and he decides to order material and make them on site or send the list to the shop and have them fabricate them ...

 we tried the whole cut to fit but by the time you have a detailer make a hanger drawing, shop fabricate/tag hundreds of hangers, and then an field apprentice sort them, and hoping they installed the correct hanger... it actually became a loss

that was our experience..

 

[sheetmetalman]

I like that idea, we have a good programmer to set rods to an increment that we feel works well, 1" or nearest 2".

My thoughts are the shop then has an easier job since there are more hangers with the same rod length, same goes for the field, less to look thru.

For the shop it means more group cutting and less measuring.

[audiocycle]

At my previous company where were utilize Fabrication CADmep we setup a procedure that the field would spot check the DELTA from a 4'-0" benchmark to underside of the deck. We would utilize that DELTA and evaluate if we had enough play from the top hoop of the clevis hanger to the cross-bar in the hanger to take-up that adjustment (this also allows for rounding up/down). We would then break up the hanger fabrication packages accordingly and stretch the hanger rods per package to accommodate for that package rod-cut length. I hope that makes sense.

[Axl]

Our increments are the nearest 4" or nearest 6" this mean the shop produces huge batches of hangers with the same rod length (faster production), the field has an easier time sorting them (less mistakes), we also send a label that if the field scans it (location correction), it will take them to specific information that will tell them the batch, level and others (we still need to add more information still)

[APD-DB]

We prefab hangers for our customers and ship them directly to their jobsite.  We round to the nearest 1/2” to eliminate so many different rod cuts especially on slope pipe.  With all things figured our average time to build a hanger is 5 minutes, the time includes making a hanger map, bulk cutting rod, spray painting hangers with color from hanger map, applying a label, and organizing them in boxes. It’s all about having a streamlined process.

We usually run with about 98-100% success.  They basically work so well that we never hear about issues and we are always asking how things are going.  If the field is trimming hangers that is a failure in my book.  We always make sure we know exactly what the structure looks like. I believe hangers are the cheapest material on the job but if prefabbed are the most valuable, they really set the pace for installing pipe and will massively increase productivity in the field. 

Also your CAD hangers need to very accurate to what is being ordered.

[bitterfitter]

Here we have been prefabbing pipe hangers for about 12 years now.  We have tried every possible option over the years and seem to have it down.  We model them exactly, and we fabricate them rounded to the 1/2".  We have found that most clevis hangers are large enough to absorb any differences.  Trapeze are not an issue at all.  The smaller line sized clevis may be tight, but we always have the option to cut them if needed.  We looked at cutting rods in 6" lengths but then we are modeling exact lengths and forcing the field to cut 100% of the rods.  by using a smaller rounding value (1/2") we can use almost all of our hangers as is, and trim very few.  The field and shop are both onboard and I very very rarely get negative feedback.  I do also call the foreman on these jobs regularly to check in and get feedback.  I found if I don't call, then issues can happen and I never hear about it until much later.  If any issues do surface, they are looked into immediately until the problem is resolved and we look out for that in the future.

[sheetmetalman]

We prefab hangers for our customers and ship them directly to their jobsite.  We round to the nearest...

APD, thanks for your insight, are you modeling in Revit or CAD?

[APD-DB]

We model in Revit but we send our hangers to autocad as that is how our process is setup.  Seems that Revit is limiting on its reporting ability out of the box.

[jbechtle]

I have been fabricating hangers since I started modeling pipe (10 years now). I have a script that cuts the hanger rods to the section and then adjusts them per the insets in the deck. For instance, if we are using blue bangers, the script adjusts the rod height per the rod diameter.
So the short answer is yes it's possible and successful.

[sheetmetalman]

We are in Revit.

Revit can be very limiting, we have jobs that are slab on metal deck in some areas and metal deck with insulation in other areas and beams in others, so we have 3 ways of attachment. Sometimes more.

-From the metal deck (where we can be in a high flute or a low flute)
-From a beam, via beam clamp
-From supplemental steel

All of these items have different rod ending locations, heck even step inserts have different rod adjustments.

Also different hangers have different take-outs, per manufacturer.

[cjehly]

I have been fabricating hangers since I started modeling pipe (10 years now). I have a script that cuts the hanger rods to the section and then adjusts them per the insets in the deck. For instance, if we are using blue bangers, the script adjusts the rod height per the rod diameter.
So the short answer is yes it's possible and successful.

this is the correct answer, imho.  All hangers are set to soffit, and you post-process the exact hanger length with a script, depending on inserts used for that job.

 I also approve of cutting hangers at set lengths and letting the field trim them, because keeping track of each hanger is a b!sh for the shop, and the field... The slickest setup I've seen is having the hangers already placed on the fab, but that induces a shipping problem, and bent/unusable hangers, and not all fab has 2 hangers to independently support it. 

[dopefish]

I have been fabricating hangers since I started modeling pipe (10 years now). I have a script that cuts the hanger rods to the section and then adjusts them per the insets in the deck. For instance, if we are using blue bangers, the script adjusts the rod height per the rod diameter.
So the short answer is yes it's possible and successful.

this is the correct answer, imho.  All hangers are set to soffit, and you post-process the exact hanger length with a script, depending on inserts used for that job.

 I also approve of cutting hangers at set lengths and letting the field trim them, because keeping track of each hanger is a b!sh for the shop, and the field... The slickest setup I've seen is having the hangers already placed on the fab, but that induces a shipping problem, and bent/unusable hangers, and not all fab has 2 hangers to independently support it.

Just wanted to chime in here and say once we started using pypeserver with a material pusher and printer, tracking solved itself. We don't use any rounding but we do group like hangers with the same item number. We run a script to adjust to soffit as well as one that identifies if the rod is in or out of the pan deck and adjusts it. In revit we will go as far as to model the pan deck so the attach to structure function does the work for us.

When we did our testing and tracking we used a project with roughly 10k hangers and we were getting over 99% accuracy.