The GO / NO GO thread plug gauges for BSPP ISO 228 G parallel pipe threads are inspection tools designed to quickly and reliably verify the conformity of internal cylindrical Gas threads according to ISO 228. They are used for dimensional checking of female threads on fittings, valve bodies, pneumatic components, hydraulic parts, fluid power elements, mechanical parts and machined components where correct compatibility with BSPP / BSP parallel threads must be ensured.

The GO / NO GO configuration provides a practical and immediate thread inspection method. The GO side must screw correctly into the threaded hole, confirming that the internal thread meets the minimum acceptance conditions and can be used for assembly. The NO GO side, on the other hand, must not screw in beyond the specified limit, helping identify oversized, deformed, out-of-tolerance or non-conforming threads. This inspection method is particularly useful in quality control departments, production areas and incoming inspection, because it allows thread conformity to be checked without complex measuring procedures during every operational control.

BSPP / BSP ISO 228 parallel pipe threads use a 55° Whitworth profile and are widely used in industrial fittings, fluid systems, pneumatics, hydraulics and non-tapered connection systems. Unlike tapered pipe threads, G parallel threads do not normally achieve sealing by thread interference, but by means of gaskets, washers, shoulders or dedicated sealing elements. For this reason, correct inspection of the internal thread is essential to ensure proper engagement, assembly repeatability and compatibility with the intended male fitting.

The hardened steel construction with hardness 58 HRC ±2 provides high wear resistance, dimensional stability and long-term reliability, even under repeated inspection in production environments. The high manufacturing quality of the gauges supports accuracy and repeatability during checking, reducing the risk of accepting non-conforming components or rejecting correct parts due to unsuitable inspection tools.

The correct gauge must be selected according to G thread size, corresponding pitch, ISO 228 standard and required inspection function. It is important to correctly distinguish gauges for BSPP parallel pipe threads from gauges for BSPT tapered threads or other inch-based standards, because geometry, connection function and inspection method are not interchangeable. During use, the gauge must be screwed in without forcing, keeping it coaxial with the threaded hole and ensuring that the thread is clean from chips, burrs, dirt or machining residues. Forced or misaligned use may damage both the gauge and the inspected component.

These thread plug gauges are suitable for quality control, mechanical workshops, fitting production, industrial maintenance, inspection departments, CNC machining, hydraulics, pneumatics and fluid power applications. They allow simple and repeatable verification of internal BSPP parallel pipe threads, improving process control, connection reliability and final product quality.