Measuring Screw Threads - Drain Plug

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Measuring Screw ThreadsExternal Threads - Drain PlugsMeasure the diameter over the thread using a caliper. The caliper reads directly in inches(fractions) and for the nominal size just above the 0 point on the caliper. Above diagram shows about 1/2 .Worn Threads are usually the pitch or TPI using the Screw thread gauges. Compare the O/D and pitch with the thread data chart to establish the Threads - Sump HolesUsing the caliper, measure the Minor Diameter. The pitch can be checked as shown. Again refer to the data HEREor READ HERENOMINAL O/DINTERNAL EXTERNALMINOR Popular thread SizesAmerican National Standard Taper Pipe Threads (NPT)NomialO/D TPIMinor DiameterThread Size(mm)(mm)written as-1/4" 18 11 1/4 - 18 NPT3/8"17 18 3/8 - 18 NPT1/2"21 14 18 1/2 - 14 NPT3/4" 14 3/4 - 14 NPT1"33 29 1 - NPT1 1/4"42 38 1 1/4 - NPT 1 1/2"48 44 1 1/2 - NPTBritish Standard Pipe Threads (BSP) may be tapered (BSPT)NomialO/D TPIMinor DiameterThread S

Measuring Screw Threads External Threads - Drain Plugs Measure the diameter over the thread using a caliper. The caliper reads directly in inches(fractions) and ...

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