Taper thread gauge are used for inspection of R(Rc,Rp) defined in JIS B 0253. Thread of workpieces R and PT are similar in dimensions but the gauging systems are different. It passes if the pipe or the end of the pipefittings is within the range of the length of the notch of the gauge.
Major Differences listed below
1. For the R thread gauge, the thread ring gauge and thread plug gauge are independent and for the thread ring gauge, the cpg (CP) is used.
2. For R thread gauge, the wear limit is specifild.