Process of manufacturing and using gauges for verifying threads of

Abstract

A ring gauge is made from the box end of an authenticated precision threaded member and a plug gauge is made from the pin end thereof. The pin end is machined laterally and radially at its nose to ensure complete engagement of the threads. The box end is machined laterally and radially at its internal shoulder for a similar reason. A plunger-activated seal-diameter gauge operates through a radial hole in each of the ring gauge and plug gauge thus made, so that the plungers contact the sealing surface of a measured pin end or box end. Similarly, a plunger-activated standoff gauge operates through a longitudinal opening of the ring gauge and of the plug gauge, the plungers effectively providing a measurement of standoff between the tip of the pin end being measured and the internal surface of the ring gauge shoulder or comparable standoff of the box end. Tabulated measurements of seal diameter and standoff provide data for determining the optimum number of acceptable fits between the pin ends and box ends from a plurality of measured tubular members. Similar gauges, but segmented with a gap, are used to measure taper of the measured threads. The gap size in the gauge determines if the measured taper is slow or fast relative to nominal and, if calibrated, an absolute measurement of taper.