Touching on some structural

[cfee]

This is a drafting Q: more than and ACAD Q:. I'm helping the boss out with some drawings he got that are structural drawings of a platform some of our equipment is going on. Some of the deck supporting structure (trusses) are ROUND Structural Tubing. There are 3 different designators for the tubing in this drawing. One example is something like: 14d55 where the d is the "diameter symbol". Similarly, another is 16d88, another is 16d72, while still another is 16d.750 & another like that one is 16d.625. Ok, I get the decimal # (eg: .625)being a wall thickness. But here's 72 & .750. is the 72 Weight per foot ? I looked in my RYERSON book on-line, and their size only goes to 12", so before I express an opinion to the boss and we try to work with that, I'd like a higher confidence level.

Thoughts?

Tks-
C.Fee

 

[tr1ntx]

14" Sch40 pipe is 54.57 lb/ft (14" OD w/ 0.375" wall), so that sure seems like it would match the 14d55 callout.

Following that logic though, leads nowhere. 16d72 does not match a pipe size, nor does 16d88.

However, using inch fraction wall thicknesses, 16" OD x 7/16" wall (0.4375) is 72.79 lb/ft, and if you calculate it at the bottom of the tolerance range, you get below 72.5, so it rounds down. 16d88(lb/ft) would be 16" OD x 17/32" wall (0.53125). Maybe they use wt/ft on the "in between" frctions.

OR -
it could be D/t ratio (Diameter / thickness).
14d55 would be 14" OD x 0.255
16d72 would be 16" OD x 0.222
16d88 would be 16" OD x 0.182

Does it make more sense for the 16d88 to be thick or thin? You have other thick ones, so I doubt if 0.182 wall makes sense.

This is odd stuff no matter how you look at it. It's not converted from metric is it? Somebody might have screwed up the conversion calculation, or just stuck too closely to the value instead of rounding to the next inch fraction. 16d72 could mean 23/32" wall (0.71875 rounded to 0.72) and 16d88 could mean 7/8" wall (0.875 rounded to 0.88), but they left off the decimal. Freakin' drafters...

 

[cfee]

trintx- Thanks for the response. Normally "pipe schedules" are for smaller sizes (1-12"nom), and aren't suitable for structural work where the larger sizes are needed (14-16"+). The designations as provided were standard designations, so they have some standard meaning. You're probably right on, but you got to the same point I did which was to observe that (in the example you used) 16d88 COULD mean wall thickness (7/8"w) OR WPF (!) which makes overall interpretaation ambiguous. I'll work with what you provided to see if I can feret out a consistent clue, and I'll share results (if any) back here.

If anyone can contribute further, I'm sure trintx & I would both be grateful. I bet we're not the only ones !

Tks-
C.F.

 

[cfee]

For anyone interested, I found the answer-

for instance- callout: 16d73: 16"OD (as expected) WPF=72.86 (73) = a wall thickness of .438. SO if there's not a clear decimal callout like .625 & .750, a 2-# designation like in the example is the Wight Per Foot, rounded !

Thanks !
C.F.