This standard establishes the basic triangular profile forMJB thread form@ the design profiles@ standard pitches@ tolerance classes@ formulae for tolerances and dimensions@ tolerance tables@ and a system of designation. Because of the specialized application for buttress threads@ no preferred diameter-pitch series have been established for this standard and each application will require use of the thread formulae for dimensionsl and related tolerances given herein for deriving the thread dimensional requirements. Purpose This standard specifies the chacteristics of the MJB metric series of buttress srew threads based on 7?/45 form@ with width of truncation same as MJ screw the thread profile@ and with a controlled radiused root in the external thread.