What Are BSPP & BSPT Fittings?

BSPP and BSPT are two thread standards developed in the United Kingdom and widely used in hydraulic and fluid power systems around the world. Both fall under the British Standard Pipe (BSP) specification, but they differ in how they seal and connect. At Gear House Hydraulics, we stock a full range of both types in carbon steel and stainless steel for industrial, mobile, and instrumentation hydraulic systems.

BSPP — British Standard Pipe Parallel

BSPP (also called G thread or BSP Parallel) uses a straight, non-tapered thread profile. The thread diameter stays consistent along the full length of the fitting. Because the thread itself does not taper to create a seal, BSPP fittings rely on a sealing element typically a bonded seal (Dowty seal), an O-ring face seal, or a soft-metal washer seated against a flat or chamfered face to achieve a leak-free connection.

Common BSPP Applications:

•       Hydraulic manifolds and valve bodies

•       Fluid transfer systems in manufacturing plants

•       Pneumatic equipment and compressed air lines

•       European and Asian OEM hydraulic machinery

•       Marine and offshore hydraulic systems

BSPT — British Standard Pipe Tapered

BSPT uses a tapered thread that gradually decreases in diameter along its length. When tightened, the taper creates an interference fit between male and female threads, forming a mechanical seal. PTFE thread tape or anaerobic thread sealant is typically applied to improve the seal and prevent galling. BSPT is the BSP equivalent of the American NPT standard both are tapered pipe threads, but they are not interchangeable.

Common BSPT Applications:

•       Pipe fittings and plumbing connections

•       Hydraulic pump and motor ports (ISO-standard equipment)

•       Agricultural and construction machinery

•       Oil and gas equipment imported from the UK, Europe, and Asia

•       Power generation and mining hydraulic systems

BSPP vs. BSPT — Side-by-Side Comparison

Use the table below to quickly identify which thread type you are working with and how each seals:

Feature	BSPP (G Thread)	BSPT (R Thread)
Thread Profile	Parallel (straight)	Tapered (self-tightening)
Also Known As	G thread, BSP Parallel	R thread, BSP Tapered
Seal Method	Bonded seal, O-ring, or face washer	Thread interference + PTFE tape or sealant
Thread Angle	55° Whitworth form	55° Whitworth form
Taper Rate	No taper (0°)	1:16 taper (3.58°)
Reusable?	Yes, seal can be replaced	Yes, with fresh sealant
Pressure Rating	High (seal-dependent)	High (thread-dependent)
Common Sizes	1/8" to 6"	1/8" to 6"
US NPT Compatible?	No — not interchangeable	No — different taper angle
ISO Standard	ISO 228	ISO 7-1

 

How to Identify BSP Thread Type

Confusing BSPP and BSPT is one of the most common mistakes in hydraulic fitting selection. Here is how to tell them apart quickly:

Visual Inspection

•       BSPP threads look uniform along the full thread length  the diameter does not change.

•       BSPT threads visibly narrow toward the end  you can see the taper when held at eye level.

•       A BSPP male thread will spin freely inside a BSPP female port; BSPT will tighten progressively.

Thread Gauge & Measurement

•       Use a thread pitch gauge to confirm the 55° Whitworth thread form this rules out NPT (60°) and Metric (60°) threads.

•       Measure OD at the first thread and again several threads in, if OD changes, it's BSPT.

•       Common BSP thread pitches: 1/4" BSP = 19 TPI, 3/8" BSP = 19 TPI, 1/2" BSP = 14 TPI, 3/4" BSP = 14 TPI.

Port Markings

•       Many European and Asian hydraulic components mark ports with a "G" (BSPP) or "R" (BSPT).

•       Check OEM equipment manuals the port thread type is always specified in maintenance documentation.

BSP vs. NPT — Are They the Same?

This is one of the most frequently asked questions from US-based buyers. The short answer: No, BSP and NPT are not interchangeable, even though both are pipe thread standards and some sizes appear physically similar.

Specification	BSP (BSPP / BSPT)	NPT (US Standard)
Thread Angle	55° Whitworth	60° National Form
Origin	British / ISO	American / ASME
Taper (Tapered version)	1:16 (3.58°)	1:16 (3.58° — same rate)
Thread Form	Rounded crests & roots	Flat crests & roots
Interchangeable?	No	No
Can they thread together?	Sometimes start — will leak / cross-thread	Not reliably

 

Warning: Never force a BSP fitting onto an NPT port or vice versa. The thread forms are different enough that they may partially engage but will not seal and will damage the port. Always use a proper BSP-to-NPT adapter if you need to connect these two standards.

BSPP & BSPT Fittings Available at Gear House Hydraulics

Gear House Hydraulics supplies a comprehensive range of BSP fittings and adapters for industrial and hydraulic applications across the United States. Our inventory includes:

Steel BSPP / BSPT Fittings

•       JIC to BSPT Straight Adapters (Series 7000)

•       JIC Swivel to BSPP Straight (Series 7022)

•       BSPP Swivel to JIC Swivel Straight (Series 7023)

•       BSPP to NPTF Straight Adapters (Series 7032)

•       BSPP to Female NPTF with Bonded Seal (Series 7042-BS)

•       Male JIC to Male BSPT 45° Elbow (Series 7100)

•       Male JIC to BSPP 45° Elbow with Bonded Seal (Series 7102)

•       Male JIC to Male BSPT 90° Elbow (Series 7200)

•       Male JIC to BSPP 90° Elbow with Bonded Seal (Series 7202)

•       Male BSPP to Male BSPP Union (Series 9022)

•       BSPP to Female BSPP Swivel Straight (Series 9024)

•       Male BSPP Hex Head Plug — 60° Seat (Series 9522-P)

•       Bonded Seal Buna-N for BSPP Fittings (Series 9900)

Stainless Steel BSPP / BSPT Fittings

All of the above configurations are also available in 316 stainless steel for corrosion-resistant applications in marine, food processing, chemical, and offshore environments. See the Stainless BSPP/BSPT collection on our website.

Sealing Methods for BSPP Fittings

Because BSPP threads are parallel, they require a separate sealing device. Here are the most common methods used with our fittings:

Seal Type	How It Works	Best For
Bonded Seal (Dowty Seal)	A metal-backed rubber washer seats against a flat face under the fitting head.	High-pressure hydraulics, 24/7 service
O-Ring Face Seal	An O-ring in a groove on the male face compresses against a flat female port.	Very high-pressure, zero-leak systems
Copper / Aluminum Washer	Soft metal deforms to fill thread gaps on the seating face.	Lower-pressure plumbing & general fluid lines
PTFE Thread Tape	Used on BSPT only — wraps tapered thread to fill voids.	Threaded pipe connections, low-to-medium pressure

 

Installation Best Practices

For BSPP Fittings

•       Always inspect the bonded seal or O-ring before assembly replace if cracked or deformed.

•       Hand-tighten first to ensure proper thread engagement, then torque to specification.

•       Do not over-torque BSPP sealing depends on the face seal, not thread crush.

•       Check the mating port face for nicks or scratches; a damaged face will cause leaks regardless of seal condition.

For BSPT Fittings

•       Apply 2–3 wraps of PTFE tape clockwise (as viewed from the male thread end) before installation.

•       For high-pressure or vibration-prone systems, use anaerobic thread sealant (e.g., Loctite 567) in addition to or instead of PTFE tape.

•       Tighten to approximately 2–3 turns past hand-tight, or to the manufacturer’s torque specification.

•       Allow thread sealant to cure per manufacturer instructions before pressurizing the system.

Why Choose Gear House Hydraulics for BSP Fittings?

Gear House Hydraulics is a specialized hydraulic fittings supplier based in Stockton, California, serving customers nationwide. Here’s why hydraulic professionals across the US choose us for their BSPP and BSPT needs:

•       Nationwide Shipping — Fast, reliable delivery to all 50 states

•       24/7 Emergency Service — We understand that downtime costs money

•       Over 20 Years of Experience in hydraulic components and fluid power

•       Carbon Steel & Stainless Steel Options in the same fitting configurations

•       Expert Technical Support — Call or email our team to confirm compatibility before ordering

•       Trusted Brands — We carry RYCO, New-Line, Tompkins, and other proven names

•       Serving Construction, Agriculture, Manufacturing, Oil & Gas, Mining, and Marine industries

Frequently Asked Questions

 

Can I use a BSPP fitting in a BSPT port?

No. BSPP is parallel and BSPT is tapered, so the thread engagement will be incorrect. In some cases they may partially thread together but will not seal reliably and can damage the port.

 

Are BSP fittings common in the United States?

BSP threads are not the US domestic standard (that’s NPT), but they are very common on imported equipment — especially machinery from Europe, the UK, Japan, and Australia. If you’re maintaining or repairing imported hydraulic equipment, chances are you’ll encounter BSP ports.

 

What is the difference between G thread and BSP?

"G thread" is the ISO designation for BSPP (British Standard Pipe Parallel). When you see a port marked "G1/2" on a hydraulic component, that means a 1/2-inch BSPP port. The two terms refer to the same thread standard.

 

Do you stock BSP-to-NPT adapters?

Yes. Our BSPP-to-NPTF adapters (Series 7032 and 7042) allow you to connect BSP-threaded imported equipment to standard US NPT ports. Browse those collections on our website or call our team for a recommendation.

 

How do I order BSP fittings from Gear House Hydraulics?

You can shop online at gearhousehydraulics.com, fill out our order form, or call us at +1 (209) 629-7113. For large or recurring orders, contact us for volume pricing.