BSPP (G) - British parallel pipe

3/8-19 BSPP

3/8-19 BSPP pipe thread: 19 TPI, major Ø 16.662 mm.

Tap drill
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16.662 mm major Ø

Profile

Thread form & key diameters

Major Ø 16.662 mmP 1.337 mm55°Root Ø 15.022 mm · Pitch Ø 15.794 mm3/8-19 BSPP19 TPI · 55° form

Dimensions

Dimensions, drill sizes and wrench sizes for 3/8-19 BSPP.
Designation3/8-19 BSPP
Major (outside) diameter16.662 mm · 0.656"
Pitch1.337 mm · 19 TPI
Pitch diameter15.794 mm · 0.6218"
Minor diameter (external)15.022 mm · 0.5914"
Minor diameter (internal)15.215 mm · 0.599"
Recommended tap drill -

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 3/8-19 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.

Open bolt schedule

What tap drill do I need for 3/8-19 BSPP?

3/8-19 BSPP is a BSPP pipe thread running at 19 threads per inch on a 16.662 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 3/8-19 BSPP?

Drill - before tapping 3/8-19 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 3/8-19 BSPP a tapered or parallel thread?

3/8-19 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 3/8-19 BSPP have?

3/8-19 BSPP runs at 19 threads per inch, a pitch of 1.337 mm, on a major diameter of 16.662 mm.

Is there a torque spec for 3/8-19 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 3/8" BSPP threads

The pipe this thread runs on

NPS 3/8 pipe

NPS 3/8 pipe is 0.675 in across the outside whatever the schedule; at standard wall (std) the wall is 0.091 in and the bore 0.493 in.

Full dimensions for the standard wall · every schedule in the chart

Nearby sizes

More bspp (g) - british parallel pipe threads