The nearest modern equivalent pipe to the ones described by Bob above is 3/4" nominal schedule 40 pipe. The differences in dimension (both OD and wall thickness) are less than 0.010" - close enough that I think it can be called a match.
One interesting observation - the pipes are made in three parts, two shorter at the ends and a longer in the middle, joined by threaded couplers. The ends of the couplers appear to be more rounded than modern equivalents, possibly a modification to make them less hard on the tarp? The construction of the pipe is such that I think it would have always been either fully installed or fully removed. I don't see how it could easily have been set up to allow only two of the three bows on a 15cwt box to be used as would have been possible with the shorter piles pictured above. Also, unlike the pipes shown above that mount to pins, these pipes seem to have been made to be fitted with carriage bolts (remnants of square holes). The ends of the pipes are slightly curved in the flattened section to wrap around the upright and reduce wear on the tarp. The sample pipes are also too long to fit the uprights of a 2B1 box.
However, most of these features (mounting style, single, full length pipe and longer overall length appear consistent with the body for a 8 cwt, which is what David Moore had.
|