Do BSPP threads create the seal?

No, this is a critical distinction. The parallel threads on a BSPP fitting only provide clamping force. The seal is created entirely by a bonded seal washer compressed between a shoulder on the male fitting and a flat face on the female port.

Can I use Teflon tape or pipe dope on BSPP threads?

Absolutely not. Since the threads do not seal, applying tape or sealant is ineffective and can introduce harmful contaminants into the hydraulic system. A bonded seal is the correct and only way to seal a BSPP connection.

A variety of forged steel BSPP hydraulic fittings on a factory table, highlighting the parallel G-threads and shoulders designed for use with bonded seals.

Steel BSPP (G Thread) Pipe Fittings

Q: What is the difference between BSPP and BSPT threads?

BSPP (G-thread) has parallel (straight) threads and requires a separate seal, like a bonded seal or Dowty washer, on a flat face. BSPT (R-thread) has tapered threads that create a seal by interference on the thread flanks. They are not interchangeable.

The International Standard for Parallel Thread Port Connections.

Understanding the G Thread and the Bonded Seal

If your team works on equipment from Europe, the UK, or much of Asia, you will encounter BSPP fittings. Standing for British Standard Pipe Parallel, and also known as a "G" thread, its defining feature is its sealing method. Unlike tapered threads (like NPT or BSPT), the parallel threads of a BSPP fitting do not create the seal.

The seal is achieved when a bonded seal (often called a Dowty washer) is compressed between a shoulder on the male fitting and a flat face on the female port. The threads simply provide the mechanical force to create this compression. This system provides an extremely reliable, reusable, and leak-free connection. We manufacture a complete line of steel adapters to help our North American partners correctly interface with the global standard. For corrosive applications, see our 316 Stainless Steel BSPP line.

BSPP Fitting & Adapter Catalog (Steel)

ORFS Male to BSPP Male Adapter (Eolastic Seal)

ORFS Male x BSPP Male Adapter (ES Seal)

Part #: 6002

Straight adapter connecting a female ORFS swivel to a female BSPP port. Male ORFS x Male BSPP (designed for sealing with Eolastic/Bonded Seal).

ORFS Male to BSPP Male Adapter Long (ES Seal)

ORFS Male x BSPP Male Adapter Long (ES Seal)

Part #: 6002L

Long version of the 6002 adapter (Male ORFS x Male BSPP with ES seal face) for extended reach.

ORFS Male to BSPP Male 45° Elbow (ES Seal)

ORFS Male x BSPP Male 45° Elbow (ES Seal)

Part #: 6058

45° adapter elbow connecting a female ORFS swivel to a female BSPP port. Male ORFS x Male BSPP (ES seal) ends.

ORFS Male to BSPP Male 90° Elbow (ES Seal)

ORFS Male x BSPP Male 90° Elbow (ES Seal)

Part #: 6059

90° adapter elbow connecting a female ORFS swivel to a female BSPP port. Male ORFS x Male BSPP (ES seal) ends.

BSPP Male Nipple / Union

Part #: 9000

Straight connector (union) with male BSPP threads on both ends for joining two female BSPP ports.

JIC Male x BSPP Male Adapter (ES Seal)

Part #: 9002

Straight adapter connecting a female JIC swivel/tube to a female BSPP port. Male JIC x Male BSPP (ES seal) ends.

JIC Male to BSPP Male Long Adapter (ES Seal)

JIC Male x BSPP Male Long Adapter (ES Seal)

Part #: 9002L

Long version of the 9002 adapter (Male JIC x Male BSPP with ES seal face).

JIC Male x BSPP Male Adapter

Part #: 9005

Straight adapter connecting a female JIC swivel/tube to a female BSPP port. Male JIC x Male BSPP ends (likely requires bonded seal).

SAE ORB Male x BSPP Male Adapter

Part #: 9006

Straight adapter connecting a female SAE ORB port to a female BSPP port. Male ORB x Male BSPP ends (requires bonded seal).

BSPP Male x NPTF Pipe Male Adapter

Part #: 9007

Straight adapter connecting a female BSPP port (using bonded seal) to a female NPTF port (seal on threads).

BSPP Male x Female BSPP Swivel Adapter

Part #: 9015

Straight adapter connecting a male BSPP fitting to a female BSPP port, featuring a swivel nut for alignment.

BSPP Test Port Tee

Part #: 9015TP

Tee fitting with BSPP connections, incorporating a dedicated test port (often M16x2 or similar) for pressure checking.

BSPP Male x Female JIC Swivel Adapter

Part #: 9021

Straight adapter connecting a male JIC flare fitting/tube to a female BSPP port (using bonded seal).

NPTF Male Pipe x Female BSPP Swivel Adapter

Part #: 9023

Straight adapter connecting a male NPTF pipe/fitting to a male BSPP fitting (seal on NPTF threads).

Female BSPP Swivel x Female BSPP Swivel Union

Part #: 9025

Straight union connecting two male BSPP fittings using female BSPP swivel nuts on both ends.

Female BSPP Swivel x Female JIC Swivel Adapter

Part #: 9027

Straight adapter connecting a male BSPP fitting to a male JIC fitting.

BSPP Plug (Hollow Hex Socket)

Part #: 9028

Seals a female BSPP port. Male BSPP thread with an internal hex drive. Requires bonded seal or similar.

BSPP Plug (Solid Hex Head)

Part #: 9030

Seals a female BSPP port. Male BSPP thread with external hex head. Requires bonded seal or similar.

BSPP Cap

Part #: 9033

Seals the end of a male BSPP threaded fitting. Female BSPP thread, usually with internal seal face or requires gasket.

BSPP Male x Female NPTF Pipe Adapter

Part #: 9035 / 9035S

Straight adapter connecting a male NPTF pipe/fitting into a female BSPP port (using bonded seal).

BSPP Male x Female ORB Adapter

Part #: 9036

Straight adapter connecting a male SAE ORB fitting into a female BSPP port (using bonded seal).

NPTF Male Pipe x Female BSPP Adapter

Part #: 9037

Straight adapter connecting a male BSPP fitting into a female NPTF port (seal on male threads).

BSPP Male x Female BSPP Bushing / Reducer

Part #: 9038 / 9039

Reducer bushing connecting different BSPP thread sizes. Male BSPP external, smaller Female BSPP internal.

BSPP Male x BSPP Male Bulkhead Union

Part #: 9040 / 9040L

Connects two female BSPP swivel fittings/hoses through a panel or bulkhead. Straight union with locknut.

Female BSPP x Female BSPP Union/Coupling

Part #: 9043

Straight union connecting two male BSPP fittings. Female BSPP threads both ends.

BSPP Male to Female BSPP Swivel 90° Elbow

BSPP Male x Female BSPP Swivel 90° Elbow

Part #: 9045 / 9060

90° elbow connecting a male BSPP fitting to a female BSPP port, featuring a swivel nut for easy alignment.

BSPP Male to Female BSPP Swivel 45° Elbow

BSPP Male x Female BSPP Swivel 45° Elbow

Part #: 9047 / 9048 / 9053?

45° elbow connecting a male BSPP fitting to a female BSPP port, featuring a swivel nut for easy alignment.

Female BSPP Swivel to Female BSPP Swivel 90° Elbow

Female BSPP Swivel x Female BSPP Swivel 90° Elbow

Part #: 9050

90° elbow connecting two male BSPP fittings using female BSPP swivel nuts on both ends.

BSPP Male x BSPP Male 45° Elbow

Part #: 9051

45° elbow connecting two female BSPP ports. Male BSPP threads on both ends.

BSPP Male x BSPP Male 90° Elbow

Part #: 9052 / 9055

90° elbow connecting two female BSPP ports. Male BSPP threads on both ends.

JIC Male to Female BSPP Swivel 90° Elbow

JIC Male x Female BSPP Swivel 90° Elbow

Part #: 9056

90° adapter elbow connecting a male JIC flare fitting/tube to a male BSPP fitting.

BSPP Male x BSPT Male 90° Elbow

Part #: 9057

90° adapter elbow connecting a female BSPP port (using bonded seal) to a female BSPT port (seal on threads).

JIC Male x BSPP Male 45° Elbow

Part #: 9058

45° adapter elbow connecting a female JIC swivel/tube to a female BSPP port.

JIC Male x BSPP Male 90° Elbow

Part #: 9059 / 9059L / 9065?

90° adapter elbow connecting a female JIC swivel/tube to a female BSPP port. (Standard/Long versions may exist).

BSPP Male to Female JIC Swivel 90° Elbow

BSPP Male x Female JIC Swivel 90° Elbow

Part #: 9061

90° adapter elbow connecting a male JIC flare fitting/tube to a female BSPP port (using bonded seal).

BSPP Male x NPTF Male 90° Elbow

Part #: 9070

90° adapter elbow connecting a female BSPP port (using bonded seal) to a female NPTF port (seal on threads).

Related BSPP Accessories

Bonded O-Ring Seal (Buna-N)

Part #: 9500 Series

Standard Buna-N (Nitrile) bonded seal (Dowty washer) used for sealing male BSPP fittings against flat surfaces.

Viton® Bonded O-Ring Seal

Part #: 9500V Series

Viton® (FKM) bonded seal for BSPP fittings, offering enhanced chemical and temperature resistance.

BSPP Bulkhead Locknut

Part #: 9041

Nut used to secure a BSPP bulkhead fitting (like 9040 series) to a panel or bulkhead wall.

Using BSPP G-Port Fittings with JIC, ORFS, NPT and BSPT

BSPP shows up wherever European and Asian equipment lands in a North American hydraulic system. The fittings above are designed to bridge G-ports to the standards your hoses, tubes and manifolds already use.

BSPP to ORFS hoses: use ORFS x BSPP adapters (6002 / 6058 / 6059 series) together with our ORFS hydraulic fittings when you want a leak-free hose connection on imported G-port valves and manifolds.
BSPP to JIC tube and hose ends: JIC x BSPP straight and elbow adapters (9002 / 9005 / 9058 / 9059 / 9061 series) let you land 37° JIC flare lines on BSPP ports using a bonded seal.
BSPP to SAE ORB ports: where the component has straight-thread O-ring bosses, combine this range with our SAE ORB fittings to keep port connections straight-threaded and serviceable.
BSPP to NPT/NPTF pipe threads: for legacy pipe work, use BSPP x NPTF adapters (9007 / 9035 / 9037 / 9070 series) with our NPT/NPTF pipe fittings instead of forcing an NPT part into a G-port.
BSPP vs BSPT: when the imported port is tapered instead of parallel, match it with our BSPT fittings. Never mix BSPP and BSPT in the same connection.
When corrosion is the limiter: mirror critical G-port connections in our 316 stainless BSP fittings while keeping the rest of the system in forged carbon steel.

Engineer's Guide to BSPP Connections

Understanding the key differences between BSPP and other common thread types is the first step to a leak-free installation.

BSPP vs. BSPT vs. NPT: The Critical Differences

BSPP (G Thread): Parallel 55° threads. Seals with a bonded washer on a flat face. Reusable and does not require thread sealant.
BSPT (R Thread): Tapered 55° threads. Seals by thread interference. Not interchangeable with BSPP.
NPT/NPTF: Tapered 60° threads. The North American standard. Absolutely not interchangeable with any BSP thread.

The Golden Rule: Never mix thread standards. Attempting to connect NPT and BSP fittings will damage both components and guarantee a leak. Always use a thread gauge to identify unknown threads.

The Sealing System: The Role of the Bonded Seal

The bonded seal is the heart of the BSPP system. It consists of a metal outer ring with a vulcanized rubber ring bonded to its inner diameter. When tightened, the rubber is compressed to create a high-pressure seal against the port face, while the metal ring prevents over-compression.

Installation Best Practices

Inspect Surfaces: Ensure the male fitting's shoulder and the female port's flat face are clean and free of scratches or damage.
Use a New Bonded Seal: Never reuse a bonded seal. Place a new, correctly sized seal over the male threads before installation.
Thread by Hand: Screw the fitting in by hand until the bonded seal makes firm contact with the port face.
Torque to Spec: Use a wrench to tighten the fitting to the manufacturer's recommended torque. The goal is to properly compress the seal, not to stretch the threads.

Straight Answers to Common BSPP Questions

What is the difference between BSPP and BSPT threads?

BSPP (G-thread) has parallel threads and requires a separate seal, like a bonded washer, on a flat face. BSPT (R-thread) has tapered threads that create a seal by interference. They are not interchangeable.

Can I use Teflon tape on BSPP threads to seal them?

No. The seal on a BSPP connection is not made by the threads. Using tape is ineffective and can introduce contaminants into the hydraulic system. The seal must be made with a bonded seal (Dowty washer) against a flat port face.

Is BSPP the same as NPT?

No. They are fundamentally different and must not be mixed. BSPP has a 55° thread angle and is parallel, sealing with a washer. NPT has a 60° thread angle and is tapered, sealing on the threads themselves.

The Right Fittings for Your International Equipment.

As a global manufacturer, we keep a deep inventory of BSPP / G-thread adapters to help our North American partners service equipment from around the world. For wholesale pricing on the parts you need to get the job done, talk to our team.

Get a Quote on BSPP Fittings Need Tapered BSP (BSPT)?