Dimensions
| Designation | 1-11 BSPP |
|---|---|
| Major (outside) diameter | 33.249 mm · 1.309" |
| Pitch | 2.309 mm · 11 TPI |
| Pitch diameter | 31.749 mm · 1.25" |
| Minor diameter (external) | 30.416 mm · 1.1975" |
| Minor diameter (internal) | 30.749 mm · 1.2106" |
| Recommended tap drill | - |
BSPP (G) - British parallel pipe
1-11 BSPP
1-11 BSPP pipe thread: 11 TPI, major Ø 33.249 mm.
Tap drill
-
33.249 mm major Ø
Profile
Thread form & key diameters
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 1-11 BSPP 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.
What tap drill do I need for 1-11 BSPP?
1-11 BSPP is a BSPP pipe thread running at 11 threads per inch on a 33.249 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.
Frequently asked questions
What drill size do I need to tap 1-11 BSPP?
Drill - before tapping 1-11 BSPP. 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.
Is 1-11 BSPP a tapered or parallel thread?
1-11 BSPP is parallel. BSPP (G) threads do not seal on the thread itself; the joint seals on a bonded washer, gasket or O-ring at the face.
How many threads per inch does 1-11 BSPP have?
1-11 BSPP runs at 11 threads per inch, a pitch of 2.309 mm, on a major diameter of 33.249 mm.
Is there a torque spec for 1-11 BSPP?
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.
Same diameter
Other 1" BSPP threads
The pipe this thread runs on
NPS 1 pipe
NPS 1 pipe is 1.315 in across the outside whatever the schedule; at standard wall (std) the wall is 0.133 in and the bore 1.049 in.
Schedule 5ID 1.185"Schedule 10ID 1.097"Schedule 30ID 1.087"Schedule 40ID 1.049"Schedule 80ID 0.957"Schedule 160ID 0.815"
Full dimensions for the standard wall · every schedule in the chart
Nearby sizes