A special BSPP tap is a tap that cuts British Standard Pipe Parallel (BSPP) threads, which are straight, non-tapered pipe threads, to a non-stock specification. If your part calls for an unusual size, pitch, hand or tolerance that catalogue taps can’t deliver, Taylor Tool builds custom parallel pipe thread taps at its Cambridge, Ontario facility. BSPP is among the specialty thread forms Taylor Tool manufactures, alongside the other special thread taps the company produces for demanding industrial work.
What Are Special BSPP Taps?
Special BSPP taps are taps made to cut BSP parallel (also called G thread) internal threads when a standard off-the-shelf tap won’t meet the job’s requirements. “Special” simply means the tap is built to your drawing or sample rather than pulled from a stock list.
BSPP threads are used wherever a fitting needs to screw into a port without the threads themselves forming the seal. They follow the Whitworth 55 degree thread form, with rounded crests and roots, and the thread diameter stays constant along its length. Taylor Tool lists BSPP among the specialty thread forms it manufactures, so a custom BSPP tap sits squarely within its core work as a Canadian tap manufacturer.
If your application uses the tapered version of this thread, see Taylor Tool’s related post on special BSPT taps, which covers custom tapered pipe thread taps.
BSPP vs BSPT: Parallel vs Tapered Pipe Threads
BSPP threads are parallel and seal through a bonded washer or O-ring at the fitting face, while BSPT threads taper and seal on the thread flanks themselves. Both share the Whitworth 55 degree thread form, which is why they’re easy to confuse on a print.
| Feature | BSPP (G thread) | BSPT |
|---|---|---|
| Thread profile | Parallel (straight) | Tapered |
| Sealing method | Bonded washer or O-ring seal at the face | Thread-to-thread seal, often with sealant |
| Tap type | Parallel pipe thread tap | Tapered pipe thread tap |
| Thread form | Whitworth 55 degree | Whitworth 55 degree |
| Typical use | Hydraulic ports, fittings with face seals | Pipe connections sealed on the thread |
So, do BSPP threads seal on the threads? Not on their own. Because the thread is parallel, the seal comes from the washer or O-ring compressed against a flat or counterbored surface. That makes the tapped hole’s thread quality, and the face or counterbore around it, equally important. For the tapered case, read Taylor Tool’s article on special BSPT taps.
When a Standard BSPP Tap Won’t Do
You need a special BSPP tap when your thread falls outside what stock taps cover: an unusual size or pitch, an oversize or large diameter, a left-hand thread, or a special tolerance or class. Materials and production volume can push you toward custom as well.
Common triggers for going custom:
- Unusual size or pitch. Taylor Tool builds taps for unusual pitches that general suppliers don’t stock.
- Oversize or large-diameter threads. Large-diameter parallel pipe threads are rarely on a distributor’s shelf.
- Left-hand threads. Reverse-threaded ports and fittings need a left-hand tap built to match.
- Multi-lead forms. Taylor Tool also manufactures taps for multi-lead threads.
- Special tolerance or class. If your application needs a tolerance different from a standard tap’s, specify it on your drawing and ask about it when quoting.
- Difficult materials or high volume. When tool life drives your cost per hole, a tap built for your material and your cycle can pay for itself.
Can BSPP taps be made left-hand or in oversize diameters? Yes. Taylor Tool’s engineering team builds left-hand and large-diameter taps to specification. For a broader look at how custom taps are scoped, see Taylor Tool’s overview of special purpose taps.
Choosing the Right Tap Style and Material
Match the flute style to your hole type and the tap material to your workpiece. Get those two choices right and most threading problems, from packed chips to premature wear, go away.
Flute style
- Spiral point tap: pushes chips forward, which makes it the usual choice for through holes.
- Spiral flute tap: pulls chips up and out of the hole, which suits blind holes and stainless steel.
- Form tap: forms the thread rather than cutting it, producing stronger threads with no chips in ductile materials.
So, should you use a spiral point or spiral flute tap for BSPP threads? Use spiral point for through holes and spiral flute for blind holes, then consider a form tap if the material is ductile and you want chip-free threading.
Material
- HSS taps are the general-purpose choice for most steels and non-ferrous work.
- Carbide taps deliver the wear resistance and rigidity needed for hardened steels, high-silicon aluminum and other abrasive materials, where tool life and consistency drive cost per hole.
- Powdered metal substrates offer a uniform, tough base for heavy machining.
What material should a BSPP tap be for stainless steel or aluminum? Stainless generally pairs well with a spiral flute geometry, while abrasive or high-silicon aluminum may call for carbide. Share your material when you request a quote and Taylor Tool can advise from there.
For more on the options, see Taylor Tool’s pages on special form taps and high performance spiral taps.
What to Send Taylor Tool for a Custom BSPP Tap Quote
Send a drawing or sample, plus the thread size, pitch, hole type, material and quantity. Taylor Tool’s engineering team works from your drawing or sample to deliver a tap that performs in your application.
A useful quote request includes:
- Drawing or physical sample of the part or thread
- Thread size and pitch
- Hand (right-hand or left-hand)
- Through hole or blind hole, and hole depth
- Workpiece material and hardness, if known
- Any special tolerance or class requirements
- Quantity, from a one-off prototype to repeat production runs
Taylor Tool handles everything from one-off prototypes to repeat production work. When you’re ready, use the contact page or the Request a Quote link on the site. You can also email sales@taylortool.com or call 519-658-9378.
Quality, Delivery and Support from a Canadian Manufacturer
Taylor Tool has manufactured taps in Cambridge, Ontario since 1918. Because it is a manufacturer rather than a reseller, it controls quality end to end, from the first conversation about your thread to the finished tool.
The company supplies customers from the smallest job shops to the largest industrial manufacturers in automotive, aerospace and power generation, and it offers fast, on-time shipments. For production-critical needs, ask about its 24-hour jet-tap service.
In Canada, Taylor Tool sells through a network of distributors, and its sales team can direct you to your nearest one. In the United States, the company is expanding its sales representation, so contact the team directly at 1-855-221-8277 for ordering information.
Frequently Asked Questions
What is a BSPP tap?
A BSPP tap cuts British Standard Pipe Parallel threads, which are straight, non-tapered pipe threads based on the Whitworth 55 degree form. A special BSPP tap is built to a non-stock specification, such as an unusual size, pitch, hand or tolerance.
What is the difference between BSPP and BSPT taps?
BSPP taps cut parallel threads that seal with a washer or O-ring. BSPT taps cut tapered threads that seal on the thread itself. Both use the 55 degree Whitworth form.
Is BSPP the same as G thread?
Yes. G thread is the common designation for BSP parallel threads, so a G-series port is a BSPP port. Confirm the exact standard on your drawing.
Do BSPP threads seal on the threads?
No. The thread is parallel, so the seal is made by a bonded washer or O-ring at the fitting face.
When do I need a special BSPP tap instead of a standard one?
Go special when you need an unusual size or pitch, oversize or large diameter, a left-hand thread, a special tolerance, or a tap suited to difficult materials or high-volume work.
Can BSPP taps be made left-hand or in oversize diameters?
Yes. Taylor Tool builds left-hand, oversize and large-diameter taps to your specification.
What material should a BSPP tap be for stainless steel or aluminum?
It depends on the alloy and volume. HSS suits general work, while carbide suits hardened or abrasive materials. Tell Taylor Tool your material when requesting a quote.
Should I use a spiral point or spiral flute tap for BSPP threads?
Use spiral point for through holes and spiral flute for blind holes and stainless steel.
What information do I need to request a custom BSPP tap quote?
Provide a drawing or sample, thread size, pitch, hole type, material and quantity.
Does Taylor Tool make custom BSPP taps?
Yes. BSPP is among the specialty thread forms Taylor Tool manufactures, and its engineering team builds taps to your drawing or sample.
Can I order Taylor Tool taps in the United States?
Yes. Contact the sales team directly for U.S. ordering information and distributor availability.
Ready to specify your tap? Contact Taylor Tool with your drawing and requirements to get a quote.