Units for Pipe Measurements
 

Is it just me or are pipe nipple "inches" a different length than regular inches? Our team was measuring our 1 1/4" x 12" pipe nipples today for assembling our goal only to discover that no dimension on them was 1 1/4". The closest dimension was the ID which could be rounded down to 1 3/8". If they didn't screw into the flanges that are clearly labled 1 1/4, I would think we got the wrong pipe. What's going on here? Does anyone know what the OD of the pipes is supposed to be? I think this would be a pretty valuable number for any team to know since it's what we're going to be gripping on to, and in my experience it is NOT 1 1/4".

Design Tolerances
 

I wouldn't be surprised if the manufacturing tolerance on the pipe is +/- 1/8". In any event, if the pipe you have fits into a floor flange labelled 1 1/4", I would say it would be close enough for our purposes. Just be glad it's not +/- 1", the "standard" FIRST field blueprint design tolerance that I've seen in my 5 years with FIRST...

Pipe OD
 

According to the Mechanical Trades Pocket Manual, 1-1/4 inch pipe has an OD of 1.66 in. The bigger the schedule number, the thicker the wall.

Almost all pipe is measured as Inside Dimension, except for some tubings or specialty items. In addition, commercially available nipples are often severely reamed out at the ends by the machines that cut them. So, to measure the actual ID, you'd have to get relatively far inside.

(It's been over twenty years since I worked in a hardware store but I still remember some things.)

so that's why we couldn't find any diemsion on 1 1/4" pvc that was anything like 1.25"...

*shakes head*

<whine> and you know what sucks? each nipple costs £40 here... its basically impossible to get anything in 'english' units not custom ordered </whine>

-ankur