R / Pipe Threads are used in pipe assemblies where pressure tight joint is required on threads, without use of sealing compound.

Specification:
ISO Standard:       Basic Dimensions: ISO 7/1-1994 & Gauging Practice: ISO 7/2-2000,,
BS & European standard:  BS EN 10226-3 - 2005
Indian Standard:  Basic Dimensions:  IS 554 - 1999 & Gauging Practice: IS 8999-2003.  

Manufacturing Range: 
Taper Fullform Thread Plug - Gauge No.1
Taper Fullform Thread Plug with relief - Gauge No.2
Parallel Fullform Ring -  Gauge No. 3
Taper Plain Ring - Gauge No.4.
Taper Modified Thread form Check Plug - Gauge No.5
Parallel Modified Thread form Check Ring -  Gauge No. 6

Size Range covered is from pipe diameter 1/16" to 6".  Above 6" & up to 12" Diameter gauges are manufactured as per
JIS B 0253 -1985 specification.