The differential GO / NO GO plug gauges for taper GAS pipe threads are inspection tools designed to verify the conformity of internal threads for pressure-tight threaded connections according to DIN 2999. They are used for checking fittings, sleeves, valve bodies, pneumatic components, hydraulic parts, fluid power elements, manifolds, adapters and mechanical components where correct thread geometry is essential to ensure compatibility, engagement depth and reliable mating.

The differential GO / NO GO configuration allows the thread position to be checked quickly and functionally against the specified acceptance limits. The GO side must screw correctly into the threaded hole up to the inspection position, confirming that the thread meets the minimum required conditions. The NO GO side must not exceed the specified limit, helping identify threads that are oversized, deformed, out of tolerance, produced with incorrect depth or unsuitable for final assembly. This method is especially useful in quality control departments, production and inspection of fittings or components intended for fluid systems.

DIN 2999 taper GAS pipe threads are used in connections where sealing performance can be affected by the correct relationship between profile, diameter, taper and engagement depth. For this reason, inspection with a differential plug gauge is important not only to verify that the thread accepts engagement, but also to avoid excessive clearance, unstable mating, excessive screw-in depth or threads not compliant with the required standard. These gauges must be clearly distinguished from gauges for ISO 228 parallel GAS threads, American NPT threads or other inch-based threads, because profile, sealing function, geometry and inspection method are not interchangeable.

The correct gauge must be selected according to nominal thread size, DIN 2999 standard, inspection function required by the technical drawing and compatibility with the component to be checked. When inspecting taper GAS threads, correct standard identification is particularly important because apparently similar pipe threads may have different acceptance criteria.

For reliable inspection, the gauge must be used on clean threads, free from chips, burrs, oxides, dirt, coolant residues or visible deformation. During inspection, correct coaxial alignment with the threaded hole must be maintained and the gauge must screw in without being forced, because misaligned or excessive use may affect the inspection result and damage both the gauge and the checked component. These gauges are suitable for quality control, mechanical workshops, CNC departments, fitting manufacturers, industrial maintenance, pneumatics, hydraulics, fluid power and plant engineering where taper GAS pipe threads must be checked simply, quickly and repeatably.