What Happened to Schedule 40, 80 & "-" Pipe? 1

[BSVBD]

This is nothing more than an (semi-rhetorical) inquiry and, perhaps, history lesson(ette).

What happened to Schedule 40, 80 & "-" Pipe?

"Std" = Standard = Schedule 40. "XS" = Extra-Strong = Schedule 80. "XXS" = Double-Extra Strong = Schedule "-".

Why is XXS = Schedule "-"? Why didn't XXS get a "Schedule" designation?

What does "40" and "80" mean?

Sometime after AISC 9th, while still maintaining the "Pipe" designation, the industry introduced "Round HSS" which provided some "more economical" thinner walls than the 0.322" wall of "Std".

I'm just curious as to when, how, why the "schedule" designation evolved, what was its' purpose and intent, and why it was discontinued?

I notice that PEMB (Pre-Engineered Metal Building) Industry makes great us of the thinner wall HSS. Did they have influence to the use of either "Pipe", "Schedules" or "HSS Round"?

Is there a benefit, pro or con specifying "Pipe" versus "HSS Round"?

Is this an appropriate category to post this? I've considered posting this in "Where is Engineering Going..." but, should we consider a new category of "Where has Engineering Been?"

Thank you!

 

[Teguci]

I've seen schedule 120 listed before. Also, for larger diameters, schedule 40/80 and STD/XS are not necessarily synonymous (different thicknesses for schedule 40 to STD spec). History? Probably need SlideRuleEra here. Just chalk it under the #12 rebar clause (which apparently is available now on the internet - probably has an ignorance tax added).

 

[SlideRuleEra]

racookpe1978 has the best explanation of pipe sizes that I've seen.

I do know (most) of the rebar size logic:

#2 through #8 = Bar diameter in eighths of an inch.

#9 = Old 1" square rebar size = diameter set so that nominal area is 1.00 in²

#10 = Old 1 1/8" square rebar size = diameter set so that nominal area is 1.27 in²

#11 = Old 1 1/4" square rebar size = diameter set so that nominal area is 1.56 in²

#14 = Old 1 1/2" square rebar size = diameter set so that nominal area is 2.25 in²

#18 = Old 2" square rebar size = diameter set so that nominal area is 4.00 in²

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[mk3223]

My understanding is that the pipe size and schedule terms were developed in stages through the years. In the beginning, the simple SCHEDULE system was used for the pipe sizes. As the time progressing, a more complicated pipe sizes were needed and developed, which was intended to replace the old one. However, the old system is so popular that it is still used today.

Noted that there are only some pipe sizes with Std pipe = SCH.40 and XS pipe = Sch.80, not for all sizes.

 

[TLHS]

The schedule number is an approximate ratio between the design pressure and allowable stress of the pipe. It doesn't really hold given current codes, but it's still roughly true as an approximation. STD, XS, XXS are an older standard, but are also still used.

Schedule pipe is still a thing. It's just not what the steel handbook calls up, and we've introduced structural HSS tube that's more appropriate for our uses. Tolerances are different, materials are different and dimensions are different. Pressure pipe and structural HSS are trying to do different things, so now we've got products that target the specific applications.