In hydraulic systems, thread compatibility determines whether a fitting can be installed correctly and maintain a reliable seal.

BSP and Metric are two widely used hydraulic fitting standards. They are often found on pumps, valves, cylinders, hydraulic machinery and fluid control equipment.

Although both systems are common in international markets, they are not interchangeable.

The main differences are found in:

• Thread diameter
• Thread pitch
• Thread angle
• Sealing method
• Connection structure
• Application region

HBFittings provides brass fitting solutions for different connection requirements, including brass adapters, hose barb fittings, compression fittings and threaded fittings. Its product range supports common thread standards such as BSP, BSPT, BSPP, Metric and customized thread specifications for OEM applications.

1. What Are BSP Hydraulic Fittings?

BSP means British Standard Pipe.

It is one of the most widely used thread systems in hydraulic and pneumatic equipment outside North America.

BSP fittings include two main categories:

BSPP (G Thread)

BSPP means British Standard Pipe Parallel.

Features:

• Parallel thread
• 55° thread angle
• ISO 228 standard
• Requires sealing through O-ring, washer or sealing face

Common applications:

• Hydraulic ports
• Pneumatic equipment
• Valves
• Pumps
• Pressure gauges

BSPT (R Thread)

BSPT means British Standard Pipe Tapered.

Features:

• Tapered thread
• 55° thread angle
• ISO 7-1 standard

Thread itself contributes to sealing

Common applications:

• Hydraulic adapters
• Pipe connections
• Industrial fluid systems

BSPP and BSPT are different connection systems and should be specified separately during purchasing.

2. What Are Metric Hydraulic Fittings?

Metric hydraulic fittings are based on metric dimensions and are commonly used in:

• European hydraulic equipment
• Construction machinery
• Automotive hydraulic systems
• Industrial machinery

Common metric hydraulic standards include:

• DIN 2353
• ISO 8434-1
• ISO 6149

Typical metric connections include:

• Metric male thread
• Metric female thread
• 24° cone fitting
• O-ring face seal
• Cutting ring connection

Metric hydraulic fittings are especially common in machinery designed according to European DIN standards.

3. BSP vs Metric Hydraulic Fittings Comparison Table

4. Thread Angle Difference

One of the biggest differences between BSP and Metric threads is the thread profile.

BSP Thread

• 55° thread angle
• Whitworth thread form

Metric Thread

• 60° thread angle
• ISO metric thread form

Although some sizes may look similar, the thread profile is different.

For example:

A BSP 1/2 fitting and a metric M20 fitting may appear close in diameter, but:

• Pitch is different
• Thread shape is different
• Engagement is different
• Sealing performance will not be reliable

5. BSP vs Metric Thread Marking

Correct marking is important for hydraulic fitting purchasing.

BSP Marking Examples

Metric Marking Examples

The thread specification should always include:

• Thread type
• Diameter
• Pitch
• Male/female
• Sealing structure

6. Sealing Method Comparison

BSP Hydraulic Fittings

BSPP

Uses:

• O-ring face seal
• Bonded washer
• Flat sealing surface

The thread mainly provides mechanical connection.

BSPT

Uses:

• Thread interference
• PTFE tape
• Thread sealant

The tapered thread creates the sealing effect.

Metric Hydraulic Fittings

Common sealing methods:

24° Cone

Used widely in DIN hydraulic systems.

Advantages:

• Metal-to-metal sealing
• High pressure capability
• Good vibration resistance

O-Ring Face Seal

Advantages:

• Reduced leakage risk
• Suitable for hydraulic systems
• Good for repeated assembly

7. Pressure Performance Comparison

Pressure capability depends on:

• Material
• Fitting design
• Size
• Sealing method
• Installation quality

BSP Hydraulic Fittings

Commonly used in:

• Hydraulic hoses
• Pumps
• Valves
• Pneumatic systems

Metric Hydraulic Fittings

Commonly selected for:

• High-pressure hydraulic equipment
• Mobile machinery
• Construction equipment

Metric cone fittings are widely used because the metal sealing structure provides reliable performance under vibration and pressure conditions.

8. BSP vs Metric Application Comparison

BSP Hydraulic Fitting Applications

Common in:

Industrial Equipment

• Pumps
• Valves
• Air compressors
• Hydraulic control systems

Pneumatic Systems

• Cylinders
• FRL units
• Air preparation equipment

Water and Fluid Systems

• Pumps
• Filters
• General piping

Metric Hydraulic Fitting Applications

Common in:

Construction Machinery

• Excavators
• Loaders
• Cranes

Agricultural Equipment

• Tractors
• Hydraulic attachments

European Machinery

• CNC machines
• Automation equipment
• Hydraulic power units

9. BSP vs Metric for Hydraulic Hose Connections

Hydraulic hose systems often require:

• Straight adapters
• 45° elbows
• 90° elbows
• Tees
• Reducers
• Bulkhead fittings

BSP hose fittings are common in international hydraulic markets.

Metric hose fittings are common in:

• DIN hydraulic systems
• European machinery
• OEM equipment
• Before replacement, confirm:
• Hose end standard
• Port thread
• Cone angle
• Seal type

10. BSP vs Metric Hydraulic Fittings: Installation Difference

BSP Installation

Important points:

• Confirm BSPP or BSPT
• Use correct seal
• Avoid over tightening
• Check thread engagement

Metric Installation

Important points:

• Confirm thread pitch
• Confirm cone angle
• Match tube size
• Tighten according to torque requirement

Metric fittings often require accurate matching because several thread sizes may have similar external dimensions.

11. BSP vs Metric Fittings for OEM Manufacturing

For OEM customers, choosing the correct thread standard affects:

• Assembly efficiency
• Spare parts compatibility
• Leakage prevention
• Production consistency

HBFittings supports customized brass fittings according to:

• Customer drawings
• Thread requirements
• Material specifications
• Application conditions

Possible customization:

• BSP adapter
• Metric adapter
• BSP × Metric adapter
• Custom brass hydraulic connector

12. Brass Material Selection for Hydraulic Fittings

Thread selection is only one part of fitting performance.

Material selection also affects service life.

Standard Brass

Suitable for:

• General hydraulic connections
• Pneumatic systems
• Water and air applications

CW617N Brass

Common in:

• Forged brass fittings
• Plumbing connections
• Industrial adapters

Advantages:

• Good strength
• Good corrosion resistance
• Good machinability

Lead-Free Brass

Suitable for:

• Drinking water
• Food-related applications
• Regulations requiring low lead content

13. BSP vs Metric Hydraulic Fittings Selection Guide

14. Common Purchasing Mistakes

Mistake 1: Confusing BSP and Metric

A fitting may screw in a few turns but still be incorrect.

Mistake 2: Ignoring Pitch

Example:

M18×1.5 and M18×2.0 are different fittings.

Mistake 3: Ignoring Sealing Structure

A BSPP fitting cannot simply replace a BSPT fitting.

Mistake 4: Selecting by Diameter Only

Thread diameter alone does not identify the fitting.

Mistake 5: Not Confirming Original Equipment Standard

Always check:

• Manufacturer drawing
• Existing fitting marking
• Thread gauge
• Equipment manual

15. HBFittings Brass Hydraulic Fitting Solutions

HBFittings provides brass fitting solutions including:

Brass Hydraulic Adapters

• Straight adapters
• Reducing adapters
• Male/female adapters

Brass Hose Barb Fittings

• Hose barb adapters
• Elbows
• Tees

Brass Threaded Fittings

• BSP fittings
• Metric fittings
• Customized thread fittings

Material options:

• Brass
• Lead-free brass
• DZR brass

Customization:

• CNC machining
• Thread processing
• Drawing-based production

16. Final Comparison: BSP vs Metric Hydraulic Fittings

Conclusion

BSP and Metric hydraulic fittings serve similar purposes, but they belong to different connection systems.

BSP fittings are widely used in international hydraulic, pneumatic and industrial fluid systems, especially where British pipe thread standards are applied.

Metric hydraulic fittings are mainly found in European-designed machinery and DIN hydraulic systems where metric dimensions and cone sealing structures are common.

For HBFittings customers, the correct selection should start from the existing equipment connection:

• BSP port → select BSP fitting
• Metric port → select Metric fitting
• Unknown fitting → confirm thread size, pitch and sealing method before ordering

For OEM projects, specifying the exact thread standard, material and sealing structure helps avoid installation problems and repeated replacement.