Whitworth-pipe thread as per DIN 2999
Outer thread conical abbreviation R
Description:
The conical R-outer thread has the same plane of reference to core, flank and outer diameter as the Rp-inner thread so that, it can be screwed on by hand, up to this plane of reference. The application by means of tool increase the reach of a screw and with the aid of some suitable sealant (such as hemp o Teflon strip) seals the thread connection.
Compare with DIN / ISO 228:
The cylindrical Rp-inner thread DIN 2999 has the same nominal dimension of the thread diameter and the thread profile as the cylindrical G-inner thread DIN/ISO 228, however the core and flank diameter of the G-inner have only positive allowance (as opposed to DIN 2999 with +/- tolerance). Though of that, the DIN 2999-R-con outer thread can be possible to screw into the ISO228-G-cylindrical inner thread. But because of that, that the R-con-outer thread can be screwed in „one turn” more and because of the different tolerance of the either core dimensions, from the
G-thread side appear a greater distance between the threads tips with the results of which is greater leakage path.
Never combine: ISO 228-G-cylindrical outer thread in DIN 2999-Rp-cylindrical inner thread can be too tight.
Whitworth-pipe thrad as per DIN / ISO 228
Outer thread cylindrical abbreviation G (tolerance class A)
Description:
Pipe thread for connection where the thread does not seals. This thread is mainly used for the mechanical connection of fittings and valves. Sealing of the connection can be achieved by the pressing of two sealing surfaces against each other outside of the thread and by insertion of a suitable sealer.
American conical pipe thread as per ANSI/ASME
Outer thread NPT conical
Description:
The conical NPT-outer thread has on the beginning of thread the same plane of reference L1 to core, flank and outer
diameter as the NPT-inner thread, so that, it can be screwed in by hand, up to this plane of reference. The application
by means of tool increase the reach of a screw and with the aid of some suitable sealant (such as hemp o Teflon strip)
seals the thread connection.
As both, inner thread and outer thread are conical, it redound to more thread turns, they help to sealing and support
the fastening force. The small thread flattening causes lower leakage path.
Thread types