ASME B1.12 : 1987(R2013):R2018

This Standard provides dimensional tables for externaland internal plastic flow interference-fit (Class 5)
threads of modified National thread form in the coarsethread series (NC) in sizes 0.250 in. through 1.500 in.
This is not the ANSI B1.1 UN thread form. It is intendedthat designs conforming with this Standard willprovide adequate torque conditions which fall within thelimits shown in Table 8. The minimum torques are intendedto be sufficient to insure that externally threadedmembers will not loosen in service; the maximumtorques establish a ceiling below which seizing, galling,or torsional failure of the externally threaded componentsis reduced. This Standard provides for the maximumallowable interference.Appendices A, B, C, and D contain useful informationthat is supplementary to this Standard, such as reprintsof the obsolete tentative and alternate Class 5standards, U.S. Navy ship specifications for elastic interference-fit coarse thread series from 0.250 in. through2.000 in., U.S. Navy ship specifications for Class 5Modified which includes nickel-copper-aluminum alloyexternal threads, and an interference metal comparisonof standard to non standard interference-fit threads