Metric taper external and mating parallel internal screw threads - Dimensions, tolerances and inspection
|Publication Date:||1 June 1997|
|ICS Code (Metric screw threads):||21.040.10|
Scope and field of application
This standard specifies profiles, dimensions and methods of verification for general purpose metric taper external threads intended to be mated with parallel internal threads with a basic profile as specified in ISO/DIS 68-1
Taper external threads as specified in this standard are intended for self-sealing joints, such as those employed on pipe plugs, compression couplings and lubricating nipples. They can be used in all cases where a parallel threaded joint with washer is unsatisfactory for technical or economic reasons.
For fluids such as oils, other liquids and gases, no thread sealants are required for joints where the nominal size is small. For joints of greater nominal size, it is recommended that sealants be applied, since the leaktightness of such joints decreases as the diameter increases.
A short design taper external thread has been specified along with the standard design both to be mated with general purpose IS0 metric parallel internal threads of tolerance class 4H for the pitch diameter and 5H for the minor diameter (as in ISO/DIS 965-1).