Author Topic: Stiffeners Defined Through Specifications vs Breakpoints  (Read 3296 times)

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Offline ashbTopic starter

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Stiffeners Defined Through Specifications vs Breakpoints
« on: Feb 21, 2023, 20:13:01 PM »
I don't believe this has been discussed previously, but if it has, please feel free to point me in the right direction.

Setting up specifications in our new database, I've found two different ways people define stiffener placement.

The first way is to set a stiffener for each spec, using the breakpoints to determine what size will have tie rods and how many. The second method I've seen is to have just two stiffener types set, one for two tie rods and one for a single tie rod, and simply assign the correct one to the sizes needed through the specifications.

Right now, I am doing both and while I'm fairly certain it's just overkill, I don't want to risk accidentally having the two methods contradict each other.

I would love to hear what other people have done when setting stiffeners in their specs.

This database will be used in both CADmep for use in Revit as well as in CAMduct to be fabricated in our new shop, if that helps clarify anything.


This topic has actually been talked about quite a lot over the years.

This post from this thread has been the most helpful in my searching so far:,3085.msg21202.html#msg21202

With internal reinforcements, (tie rods) we don't have any problems. It's all about database setup, which is extremely laborious. Assuming your pressure classes are set up to work to fitting lengths as well as size, you need to create a tie rod for each category in your pressure class.

For example; at 4" Smacna, a fitting that is 36" long with a 48x36 end size gets 1/2"+4 wg (3') tie rod. You have to actually get that in depth with the tie rods. If the same fitting is 48x48, it gets a 3/4"+4 wg (3') tie rod. You also have to use long side/short side set up in your specs.

To summarise,  you need a tie rod for each pressure class, each fitting length change within that pressure class, and for each tie rod diameter (we use 1/2" up to 36", 3/4" over that.) Then you have to plug the appropriate tie rod into the right place in your main spec. This was the only way we could get it to work consistently across all pressure class/size combinations. The guy that set this up now works for TSI, so it must be right! :D

I have no idea about external stiffeners; we try to stay away from them, and let the field install them.

I'm still working to make them as best as possible but creating specs using LS/SS Dimensions for the Breakpoint Style is important to get the most accurate tie rod associated with the different sizes.

I do not have stiffeners separated by spec anymore, but rather by what they are. I'm showing what I have currently under one of my specs to help better demonstrate what I mean. Doing it this way is by request of the shop and the name is visible on the stickers. Now they know from the stiffener called out what exactly a fitting gets.

I am still working on accurate hole placements, as well as leaving tie rods off connections such as flanges while remaining on for the rest of the piece.

The other struggle I have had so far is getting an accurate count and measurement of tie rods to produce a report for the shop. This thread has been helpful with that, though still not entirely working for me yet.,14030.msg95167.html#msg95167

The last thing I have not been able to do is add stiffeners to the decoiled output- but that is apparently just not possible in the program currently.

Hopefully, this is some help to others.

If you have any tips or see something that you do differently, I would love to hear it and learn more about all I'm doing wrong ;)
« Last Edit: Jun 07, 2023, 18:32:13 PM by ashb »