ISO 7-1:1994 Dimensions, Tolerances, And Designation

ISO 7-2:2000 Verification By Means Of Limit Gauges
The ISO 7 tapered Whitworth threads are equivalent to BS 21(EN10226-1) DIN 2999, & JIS B0203
Characteristics of ISO 7 tapered With worth threads are tapered thread 1o47”
truncation of roots and crests are rounded
55o thread angle pitch is measured in threads per inches
There is a distinction between jointing threads – sealing tapered/cylindrical threads for connections according to ISO 7-1 and/or EN 10226-1, BS 21
fastening threads – not sealing parallel cylindrical threads for connecting according to EN ISO 228-1, Diameter and pitches are same for ISO 7-1 and ISO 228 threads
ISO 7-1 is BSPT (R/Rp) – British Standard Tapered Pipe where
R – tapered male with external threads
Rp – cylindrical female with internal threads
Rc – tapered female with internal threads
G-threads have a parallel shape in accordance to the DIN-EN-ISO 228-1

Both female Rp – internal cylindrical threads – and Rc – internal taper threads – are used in combination with male R – external threads – to make sealed joints. Male G-threads (parallel) can only be screwed into female G-threads.
Male R-threads (tapered) can be screwed into female G or R-threads
DIN 2999 is the German version of BS 21 and BS 2779 which were the original British Whitworth screw thread pipe joint standards. DIN 2999 has been withdrawn, is obsolete and has been replaced with ISO 7 and ISO 228.
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