That should be controlled in mechanical settings>Pipe Settings>pipe fitting annotation size. You may have to select the fittings and select the "use annotation scale" in the properties box. You can select the fittings globally for the whole project or just the current view and change check the box too.
Has there been any progress on this issue? There looks to be some conflicting info in this thread.
I thought we had this issue resolved where I work. We had set the pipe rise/drop anno size to less than 1/8". That worked for plumbing. Turns out, our Fire Prot guys wanted the pipe drop to display a bit larger. Their views are scaled at 3/32" = 1'-0". The views in question are in the coarse, single-line detail-level. The WikiHelp lists: "specifies the plotted size. . . . size is maintained regardless of the drawing scale. The symbol measures differently, when you change the scale of the view (I guess it would have to, to appear the same size relative to the Arch).
Can we specify the symbol size based on scale? Seems like I've seen this discussed before. Seems like I had found some of those settings in 2012. Things have moved.
Eureka! You have to change the setting in two places.
Project Units > Piping > Pipe Size, set rounding to less than 1/8". (I set mine to 1/256")
Then, you can fine-tune the MEP Settings > Pipe Rise / Drop, to a fraction a bit less than 1/8". (21/256" for example)
This was for a 2013 project.