How to Identify Hydraulic Fittings Before Ordering: JIC, ORFS, BSPP, NPT & Metric 24°

You have a hydraulic fitting from an existing machine, but the original part number is missing. The thread looks familiar, the fitting dimensions seem close, and several replacement options appear similar.

How do you identify the correct connection before placing an order?

For industrial distributors, OEM buyers, and maintenance procurement teams, the most reliable starting point is the sealing interface—not just the thread size.

JIC 37°, ORFS, BSPP, NPT, and metric 24° connections are widely used in industrial hydraulic equipment. However, they rely on different connection geometries and sealing arrangements.

This guide explains how to distinguish these fitting types, what information to collect from an existing component, and how to prepare a clear RFQ for an alternative supplier.

1. Quick Hydraulic Fitting Identification Chart

Start by examining the connection end.

Important: This table is a preliminary identification guide. Final identification requires confirmation of the complete connection geometry, thread specification, and mating component.

For example, a parallel thread does not automatically indicate BSPP. JIC, ORFS, and many metric hydraulic connections also use straight threads.

2. Step One: Identify Where the Connection Seals

The first question should be:

Where does this fitting create its pressure seal?

Different hydraulic connections use different sealing interfaces.

JIC 37°: Conical Metal-to-Metal Contact

JIC fittings use a 37° flare connection.

The male fitting has a conical sealing surface that mates with the corresponding female flare seat.

The threads provide the mechanical force needed to bring the sealing surfaces together.

When identifying a JIC fitting, examine the cone and mating seat rather than relying on the thread alone.

A JIC 37° connection should not be confused with a 45° flare connection.

ORFS: Flat Face with an O-Ring

ORFS stands for O-Ring Face Seal.

A typical male ORFS fitting has a flat sealing face with an O-ring retained in a groove.

The mating female connection presents a compatible flat sealing surface.

This design is readily distinguishable from the conical sealing interface of a JIC fitting.

If the original O-ring is missing, inspect the face for the groove and confirm the connection using dimensions and documentation.

BSPP: Parallel Thread with a Separate Seal

BSPP connections use parallel pipe threads.

In hydraulic equipment, the sealing arrangement can vary with the fitting and mating port.

Examples include bonded seals, O-rings, metal sealing washers, and specified cone-seat arrangements.

The designation G identifies an ISO 228 parallel thread, but it does not by itself define the complete hydraulic sealing interface.

NPT: Tapered Thread Connection

NPT uses tapered pipe threads.

Unlike a typical ORFS or JIC connection, the tapered threaded joint itself participates in sealing.

Appropriate thread sealant and assembly requirements depend on the application.

NPT must also be distinguished from NPTF and other pipe-thread systems; similar appearance does not establish conformity to the same standard.

Metric 24°: Cone-Based Hydraulic Connection

Metric 24° connections are common in hydraulic tubing systems.

Depending on the specific design, the connection may use a cutting ring, another flareless arrangement, or a compatible soft-sealing component.

These connections should be identified using the relevant metric thread, tube OD, connection series, and 24° sealing geometry.

3. Step Two: Check Whether the Thread Is Parallel or Tapered

After identifying the likely sealing interface, inspect the thread.

A tapered thread changes in diameter along its length. A parallel thread maintains a substantially constant nominal diameter.

This distinction can help separate NPT from several other common hydraulic connections.

However, it is only one identification step.

A parallel thread could belong to:

• JIC 37°

• ORFS

• BSPP

• Metric 24°

• Another straight-thread hydraulic connection

Therefore, parallel versus tapered is not enough to identify a fitting by itself.

Where visual inspection is inconclusive, use suitable measurement equipment and the applicable dimensional reference.

4. Step Three: Measure the Thread Correctly

Use a caliper and thread pitch gauge to collect the relevant dimensions.

For an external thread, measure the major diameter. For an internal thread, the accessible minor diameter alone is not sufficient to establish the nominal thread designation.

Check the pitch in the appropriate units:

• Threads per inch (TPI) for applicable inch-thread systems

• Millimeters per thread for metric systems

Then compare the measurements with the dimensional tables for the suspected connection standard.

Avoid selecting a replacement simply because the measured diameter is close to a familiar nominal size.

Pipe-thread designations, straight-thread sizes, and tube outside diameters follow different naming conventions.

A nominal pipe size is not necessarily the actual measured thread diameter.

5. Step Four: Confirm the Tube or Hose Connection

A hydraulic adapter can have different connection types at opposite ends.

For example, one end may be a JIC connection while the other is a threaded port connection.

Similarly, a hose assembly may use a female swivel connection that differs from the fitting installed on the machine.

Identify each end separately.

Record:

1. Connection type

2. Thread designation

3. Male or female configuration

4. Sealing interface

5. Tube or hose size, where applicable

6. Any special swivel or port arrangement

For metric 24° connections, also identify the applicable series.

In ISO 8434-1 systems, light-series (L) and heavy-series (S) connections are distinct. A metric thread measurement alone does not establish which series is required.

6. Common Identification Mistakes

These errors are particularly relevant when replacing older components or sourcing products from different manufacturers.

A clear identification process reduces unnecessary quotation revisions and helps ensure that the proposed fitting matches the required interface.

7. How to Identify an Unknown Fitting from a Sample

When the original drawing is unavailable, follow a structured process.

First: Examine the Complete Component

Identify whether it is a straight adapter, elbow, tee, union, hose end, or another fitting type.

Photograph the entire component before focusing on individual threads.

Second: Inspect Both Connection Ends

Look for:

• Flat O-ring sealing faces

• Conical flare seats

• Tapered threads

• Parallel threads

• Metric cone geometry

• Separate washers or sealing components

Third: Record Measurements

Measure accessible thread dimensions and pitch.

Record relevant overall dimensions, especially where the replacement must fit within an existing machine.

Fourth: Check Existing References

Look for original equipment drawings, part numbers, hose assembly records, or previous purchasing documents.

These may establish the correct connection more reliably than appearance alone.

Fifth: Send the Information for Cross-Reference Review

A prospective supplier can use the measurements, photographs, and original references to identify available corresponding products.

If the connection remains uncertain, request further technical confirmation before approving the order.

8. What Should Buyers Include in a Hydraulic Fitting RFQ?

A complete RFQ helps suppliers prepare quotations for the correct product.

For repeat OEM or distributor orders, include the expected purchasing frequency where available.

If the requirement involves a special fitting or adapter, a dimensioned drawing is particularly useful.

9. Finding Alternative Hydraulic Fittings from Existing Part Numbers

Many buyers already have a list of original manufacturer part numbers.

These references are valuable when sourcing corresponding fittings from an alternative supplier.

Rather than identifying every connection from the beginning, buyers can submit the existing list together with quantities and any available drawings.

The supplier can review:

• Fitting configuration

• Connection standards

• Tube or hose sizes

• Material requirements

• Relevant dimensions

• Application requirements

• Available corresponding products

Different manufacturers may use different part numbering systems.

The purpose of cross-referencing is to establish the required specification and identify an appropriate proposed product—not to assume that all products with similar dimensions are identical.

For distributors and OEM buyers, this process can support multi-item quotations and ongoing purchasing programs.

10. Why Complete Connection Information Matters

A hydraulic fitting is selected as part of a connection system.

Even when the nominal thread size is correct, the mating geometry and sealing method must also be appropriate.

For example:

• A JIC connection requires the correct flare interface.

• An ORFS connection requires the correct mating face and seal.

• A BSPP port requires the specified sealing arrangement.

• A metric 24° connection requires the appropriate series and compatible components.

The finished product must also meet the application's material, pressure, temperature, and media requirements.

For this reason, buyers should evaluate the complete proposed fitting rather than approving a replacement based on one measurement.

11. Frequently Asked Questions

How can I tell whether a fitting is JIC or ORFS?

Inspect the sealing interface.

JIC uses a 37° conical flare seat. ORFS typically uses a flat sealing face with an O-ring groove on the male connection.

Confirm the thread and dimensions before ordering.

Is BSPP the same as NPT?

No. BSPP uses parallel threads, while NPT uses tapered threads. Their thread geometry and sealing arrangements differ.

Are all metric hydraulic fittings 24°?

No. Metric threads are used in several hydraulic connection systems. The presence of a metric thread does not establish a 24° connection.

What is the difference between metric L and S series?

They are different connection series within the relevant metric hydraulic fitting system. The appropriate series must be identified from the connection specification and dimensions.

Can I send photos of an existing fitting for quotation?

Yes. Clear photographs, thread measurements, and any original part numbers can help with preliminary identification.

A drawing or sample may still be needed for final confirmation.

Can I request an alternative to an existing international-brand fitting?

Yes. Provide the original part number, quantity, and relevant technical requirements so the supplier can review available corresponding products.

12. Request Hydraulic Fittings and Adapters from SAM-LOK

SAM-LOK supplies industrial fittings, adapters, and related fluid connection products for distributors, OEM manufacturers, and industrial procurement teams.

If you are sourcing a replacement fitting, preparing a multi-item BOM, or looking for an alternative supply source, send us the information you already have:

• Existing part numbers

• Technical drawings or clear product photographs

• Thread and connection specifications

• Material requirements

• Operating conditions

• Required quantities

Our team can review the information, identify available corresponding products, and prepare a quotation for the requested items.

Have a hydraulic fitting list or replacement requirement? Contact SAM-LOK with your BOM, drawings, or original part numbers for product review and quotation.