Dimensions, drill sizes and wrench sizes for 1-1/2-11 BSPT.
Designation
1-1/2-11 BSPT
Major (outside) diameter
47.803 mm · 1.882"
Pitch
2.309 mm · 11 TPI
Pitch diameter
46.303 mm · 1.823"
Minor diameter (external)
44.97 mm · 1.7705"
Minor diameter (internal)
45.303 mm · 1.7836"
Recommended tap drill
44.5 mm
Tightening torque estimate
Pipe threads are made up to a seal against the mating flanks, not tightened to a bolt preload, so no proof load or tightening-torque figure applies.
Put 1-1/2-11 BSPT on a job sheet
The bolt schedule collects the fasteners for one job onto a single sheet - tap drill, wrench size, grade and tightening torque on every line, taken straight from pages like this one. Free schedules hold 3 lines and are saved in this browser only.
1-1/2-11 BSPT is a BSPT pipe thread running at 11 threads per inch on a 47.803 mm major diameter. BSPT (R) is a 55° Whitworth tapered thread that seals on the flanks.
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.
Frequently asked questions
What drill size do I need to tap 1-1/2-11 BSPT?
Drill 44.5 mm before tapping 1-1/2-11 BSPT. BSPT (R) is a 55° Whitworth tapered thread that seals on the flanks.
Is 1-1/2-11 BSPT a tapered or parallel thread?
1-1/2-11 BSPT is tapered. BSPT (R) is a 55° Whitworth tapered thread that seals as the flanks wedge together, normally with thread sealant or PTFE tape.
How many threads per inch does 1-1/2-11 BSPT have?
1-1/2-11 BSPT runs at 11 threads per inch, a pitch of 2.309 mm, on a major diameter of 47.803 mm.
Is there a torque spec for 1-1/2-11 BSPT?
No. Pipe threads are made up to a seal against the mating flanks, not tightened to a bolt preload, so no proof load or tightening-torque figure applies.