9-thread

Updated: May 21, 2025

This trouble has been remedied by the 9-thread, taper-cut pipe of the present day, which is tested at the mill to 1,500 pounds pressure, while the average duty required is 1,200 pounds; as the iron used in the manufacture of this line-pipe will average a tensile test strain of 55,000 pounds per square inch, the safety factor is thus about one-sixth.

Various - Scientific American Supplement, No. 497, July 11, 1885