NPT Helicoil Type Inserts
There are also NP parallel threads and the most common one is known as NPSM which stands for National Pipe Straight Mechanical.
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Metric (ISO) Tapped Hole Sizes Table
UNC Tapped Hole Sizes Table
UNF Tapped Hole Sizes Table
BSW/BSF Tapped Hole Sizes Table
BSPP/BSPF Tapped Hole Sizes Table
BA Tapped Hole Sizes Table
NPT Tapped Hole Sizes Data
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