Hydraulic Adaptor Standards Explained

Hydraulic adaptor standards define thread forms, sealing methods, dimensions, and pressure capability. Selecting the correct standard for the job ensures compatibility, reduces leaks, and improves system reliability.

We’ve put together a concise breakdown of common threads and their respective international standards below, but here’s the general gist:

JIC offers simplicity and broad compatibility
ORFS prioritises leak-free performance under pressure and vibration
BSP remains widely used but requires careful identification
Metric DIN (L/S) provides structured pressure ratings and durability
Code Flanges deliver the highest reliability for large, high-pressure applications

JIC (37° Flare)

Standards:

SAE J514
ISO 8434-2

Defines:

37° flare geometry
UNF (Unified Fine) threads
Dimensions and tolerances

Seal type:

Metal-to-metal flare

Customer impact:

Widely available and interchangeable
Easy to assemble
Less resistant to vibration compared to ORFS

ORFS (O-Ring Face Seal)

Standards:

SAE J1453
ISO 8434-3

Defines:

Flat sealing face
O-ring groove and dimensions
Thread form

Seal type:

Elastomeric O-ring

Customer impact:

High leak resistance
Suitable for high pressure and vibration
Higher cost, O-ring condition critical to performance

BSP (British Standard Pipe)

Standards:

ISO 228-1
ISO 7-1
BS 5200

Defines:

55° thread form
Parallel vs tapered threads
Thread dimensions

Seal type:

BSPP: bonded seal/O-ring/seat
BSPT: taper thread interference

Customer impact:

Very common globally
Must correctly identify BSPP vs BSPT
Not interchangeable with NPT

Metric DIN (L&S Series)

Standards:

ISO 228-1
ISO 7-1
BS 5200

Defines:

55° thread form
Parallel vs tapered threads
Thread dimensions

Seal type:

BSPP: bonded seal/O-ring/seat
BSPT: taper thread interference

Customer impact:

Very common globally
Must correctly identify BSPP vs BSPT
Not interchangeable with NPT

Code Flanges (SAE)

Standards:

SAE J518
ISO 6162
ISO 6164

Defines:

Flange dimensions and bolt patterns
O-ring groove
Pressure classes (Code 61/Code62)

Seal type:

O-ring face seal

Customer impact:

Best for high pressure and large bore
Reliable, low leak risk
Requires more space and hardware

As you can see, choosing the correct thread is less about preference and more about application. Matching the fitting type to the system’s pressure, environment, and service conditions will directly impact safety, reliability, and long-term cost.

Incorrect selection or misidentification is a common cause of failure, so understanding these standards is a critical part of system performance and risk management. If you’re ever in doubt, reach out to our team and we’ll set you on the right path.