BSPP Parallel Pipe Thread (G) · ISO 228-1 / DIN 259

G 1 5/8" Thread: Pitch, Tap Drill & Dimensions

G 1 5/8" is a BSPP Parallel Pipe Thread (G) (ISO 228-1 / DIN 259) size, with a major diameter of 52.883 mm, 11 threads per inch (2.309 mm pitch). The tap drill is 49.926 mm.

Profile shape (schematic, not to scale)
G 1 5/8" thread dimensions
Major Diameter (inch)2.082
Major Diameter (mm)52.883
Minor Diameter Nut (mm)50.566
Tapping Drill Size (mm)49.926
TPI11
Pitch (mm)2.309
Flank angle55°

Common questions

What size drill do I use to tap G 1 5/8"?

Use a 49.926 drill. This is the standard tap drill for G 1 5/8"; for hard materials or deep threads a slightly larger drill reduces tapping torque.

What is the pitch of G 1 5/8"?

The pitch of G 1 5/8" is 2.309, meaning the thread advances that distance in one full turn.

Where can I find other BSPP Parallel Pipe Thread (G) sizes?

The full BSPP Parallel Pipe Thread (G) table, with every size and a live filter, is on its standard page, and the Thread Finder searches all 73 standards at once.

Reference values; computed values use the ISO basic profile. Verify against the current standard before production use.

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