Originally Posted by Targos_2
So then I really shouldn't have problems with 1-1/4"ips schedule 40 aluminum for side rails and seat crossbars strength? I understand that the was thickness is increased from sch 40 to sch 80, so the tubing is stronger, but does the strength of the tubing also increase with and increase of isp?
Just went out to the shop and applied a micrometer to a piece of 1.25" NRS frame pipe— looks like schedule 40 to me: the wall is 9/64" or 0.141". (I'll post info for the generally used sizes below.)
The strength does
increase for larger diameter pipe, since there's more metal per given length. So schedule 80 pipe is both stronger and heavier— probably too heavy for the entire frame, unless you're hauling pianos down waterfalls.
The one spot I might use sch. 80 in a frame of NRS-size pipe* would be for a rowing seat mounted on a single bar, on a wide frame. Where a 250 lb. dude slamming his butt down could exert a pretty large load.
Here are specs (click for a readable size) for the sizes of aluminum pipe commonly used in raft frames from http://www.onlinemetals.com
(fair for price and excellent for info).
Schedule 40 aluminum pipe
Schedule 80 aluminum pipe
*Although we often call it frame tubing
, in the metals biz it is pipe
. Pipe is stiffer and stronger than the stuff sold as tubing (think lawn chairs