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Sizes · Pipe (NPT / BSPT / BSPP)

BSPP (G) — British parallel pipe

1-1/4-11 BSPP

1-1/4-11 BSPP pipe thread: 11 TPI, major Ø 41.91 mm.

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41.91 mm major Ø

Profile

Thread form & key diameters

Major Ø 41.91 mmP 2.309 mm55°Root Ø 39.077 mm · Pitch Ø 40.41 mm1-1/4-11 BSPP11 TPI · 55° form

Dimensions

Designation1-1/4-11 BSPP
Major (outside) diameter41.91 mm · 1.65"
Pitch2.309 mm · 11 TPI
Pitch diameter40.41 mm · 1.591"
Minor diameter (external)39.077 mm · 1.5385"
Minor diameter (internal)39.41 mm · 1.5516"
Recommended tap drill—

What tap drill do I need for 1-1/4-11 BSPP?

1-1/4-11 BSPP is a BSPP pipe thread running at 11 threads per inch on a 41.91 mm major diameter. BSPP (G) is a parallel thread sealed by a bonded washer or gasket, not by thread interference — so it has no tapered tap-drill sizing.

All values are generated from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables — not hand-entered. See the full reference.

Same diameter

Other 1-1/4" BSPP threads

1-1/4-11 BSPTTap 38.75 mmØ 41.91 mm · pitch 2.309 mm

Nearby sizes

More bspp (g) — british parallel pipe threads

1-1/2-11 BSPPTap —Ø 47.803 mm · pitch 2.309 mm1-11 BSPPTap —Ø 33.249 mm · pitch 2.309 mm3/4-14 BSPPTap —Ø 26.441 mm · pitch 1.814 mm2-11 BSPPTap —Ø 59.614 mm · pitch 2.309 mm1/2-14 BSPPTap —Ø 20.955 mm · pitch 1.814 mm3/8-19 BSPPTap —Ø 16.662 mm · pitch 1.337 mm1/4-19 BSPPTap —Ø 13.157 mm · pitch 1.337 mm1/8-28 BSPPTap —Ø 9.728 mm · pitch 0.907 mm