These are pipe threads where pressure-tight joints are not made on threads. Gauge dimensions are as per ISO 228-2.
|Therad Ring gauge||A' & 'B'|
|Therad Plug gauge||-|
Acceptance criteria for components:
The GO gauge when screwed by hand without using excessive force, should enter and pass the whole length of the workpiece thread. The NOT GO gauge when screwed by hand without using excessive force, should not enter the component by more than two turns of the thread from both ends.