The GO ring gauges for G BSPP parallel pipe threads are inspection tools designed to verify the functional acceptance of external parallel threads according to DIN ISO 228 part 1. They are used to check male fittings, nipples, adapters, threaded bodies, valve connections and mechanical components intended for non-pressure-tight threaded joints, where correct compatibility of the external thread is essential to ensure smooth assembly, proper mating and reliable functional performance.

These ring gauges perform the GO function and must screw correctly onto the external thread without forcing, confirming that the thread meets the minimum acceptance conditions required for mating with the corresponding female component. They are therefore suitable for quick and repeatable checking of external thread usability in production, quality control, final inspection, maintenance and incoming inspection. They do not replace the upper tolerance limit check performed by a NO GO gauge, but they are an essential tool for the initial functional inspection of the male threaded component.

G parallel pipe threads, also known as BSPP, use a 55° Whitworth profile and are employed in non-pressure-tight threaded connections. In these joints, sealing is generally not achieved by thread interference, but by gaskets, washers, flat seats, O-rings or other dedicated sealing systems. For this reason, checking the external thread is important to ensure proper screw-on capability, dimensional compatibility, absence of deformation and correct engagement with the internal thread of the receiving fitting or component.

The correct gauge must be selected according to the nominal G size, the pitch defined by ISO 228-1 and the function of the component to be checked. It is essential to distinguish these gauges from those for BSPT taper pipe threads, NPT, metric or other inch-based standards, because profile, mating function and inspection method are not interchangeable.

For reliable inspection, the GO ring gauge must be used on clean external threads, free from chips, burrs, oxides, dirt or machining residues. During checking, the gauge must be screwed on without forcing and with proper alignment to the thread axis, because misaligned or excessive use may affect the inspection result and damage both the gauge and the checked component. These ring gauges are suitable for mechanical workshops, fitting manufacturers, CNC departments, quality control, industrial maintenance, pneumatics, hydraulics, fluid power and plant engineering where conformity of external G BSPP threads must be checked simply, quickly and repeatably.