6J Adapter – JIC Male 74° Cone Bulkhead Hydraulic Adapter (SAE J514)

The 6J adapter is a straight bulkhead hydraulic tube fitting with a JIC 74° cone male end at each side, made to SAE J514. Its body passes through a panel, wall or frame and is locked in position by a bulkhead nut, so a hydraulic connection can be made from both sides of that wall. Both ends are male 74° cone stud ends, which makes the 6J adapter a stud with a bulkhead hex rather than a coupling.

Both connection ends must match their mating seat exactly in thread size, cone angle and seat condition, because that exact match is the precondition for eliminating leakage at the conversion point. The panel the body passes through carries no pressure, so the joint quality depends on the two cone seats and on the bulkhead nut holding the body square in the panel.

Sealing principle of this series: each end carries a 74° external cone that seats metal-to-metal on the 74° internal cone of the mating seat, with no elastomer in the sealing path. The 6J adapter is supplied as the stud only, so the nut and sleeve that complete each joint are ordered separately.

Core Advantages

• Bulkhead body that passes through a panel and is locked by a bulkhead nut, so a line connects from both sides of a wall or frame.
• JIC 74° cone male ends to SAE J514 on both sides, matched to the mating 74° cone seats.
• Two hex features printed as S1 and S2, so the body is held while the bulkhead nut and the tube nuts are tightened.
• 11 printed sizes from 7/16″x20 to 2.1/2″x12, all equal ended.
• Lock nut option ordered with the suffix LN, for example 6J-12LN.
• Carbon steel with trivalent chromium zinc plating, or 304 / 316 stainless steel for corrosive service.

1. What a 6J Adapter Does

A 6J adapter brings a hydraulic line through a wall, panel or frame and gives a working 74° cone connection on each side of it. The body sits in a hole in the panel, the bulkhead nut is run down on the body thread until it clamps the panel, and the two ends are then free to be made up from either side.

The bulkhead principle in full: the body is longer than the thread of either connection, so it can pass through a structural member. A shoulder or hex on one side of the panel and the bulkhead nut on the other side trap the panel between them. The panel is not part of the pressure path; it only positions the adapter. Because the two ends are independent, a tube assembly inside an enclosure and a second tube assembly outside it are joined at one fixed point instead of through a loose hose run.

That feature is why a bulkhead fitting is used wherever a line crosses a boundary: a cab wall, a machine frame, a tank wall or the bulkhead of a marine installation. The panel takes the routing load and the adapter takes the pressure.

Both ends are JIC 74° cone male stud ends to SAE J514 and every printed row is equal ended, so the same thread size appears on both sides of the panel.

The 74° cone joint is a metal-to-metal seat, so the condition of the cones governs the result: a nicked or flattened cone leaks no matter how much torque is applied afterwards.

2. 6J Specifications

The two ends are presented as mirrored blocks. Read the E block for the first side and the F block for the second, then confirm this JIC adapter against both mating assemblies.

2.1 Connection 1 – JIC 74° cone male end (E)

• Thread standard and family: SAE J514, JIC 74° cone seat family.
• Thread size range available at E: 7/16″x20 through 2.1/2″x12, in the steps printed in table 2.5.
• Gender: male stud end.
• Sealing method: 74° external cone seating metal-to-metal on the mating 74° internal cone.
• Mating port standard: SAE J514 74° cone seat, made up with the matching nut and sleeve for the tube.

2.2 Connection 2 – JIC 74° cone male end (F)

• Thread standard and family: SAE J514, JIC 74° cone seat family.
• Thread size range available at F: the same 11 steps as connection 1. Every row of the printed table is equal ended.
• Gender: male stud end.
• Sealing method: 74° external cone seating metal-to-metal on the mating 74° internal cone.
• Mating port standard: SAE J514 74° cone seat, made up with the matching nut and sleeve for the tube.

Connections 1 and 2 are the same family, the same sealing type and the same size; the only difference is which side of the panel they sit on.

2.3 Construction and Materials

The body is machined from bar stock on CNC lathes. Both cones, the thread forms, the bulkhead thread and the hex features are turned in one family of setups, so the two ends stay concentric with the body that passes through the panel.

• Body material: carbon steel as standard; 304 stainless steel, 316 stainless steel or brass on request.
• Plating: trivalent chromium zinc plating (Cr3+) for carbon steel as standard; zinc-nickel plating available. Plating thickness and corrosion performance are confirmed per order rather than published as a series figure.
• Seal material: the 74° cone joint is metal-to-metal, so this adapter fitting carries no elastomer in the sealing path. Where the same circuit uses elastomer-sealed components, NBR, FKM and EPDM are the available seal compounds.
• Machining process: bar-stock turning, thread form produced to the port standard, cone checked against the drawing, bulkhead thread gauged.
• Bulkhead features: the body is longer than either end thread, with two hex features printed in the table as S1 and S2, and a bulkhead thread that carries the lock nut when the LN option is ordered.

2.4 Pressure and Temperature

Working pressure for a 6J adapter is not set by the series code. It is governed by the thread size, the wall thickness of the stud and the tube, the sealing method and the material selected, and the panel fixing has to be checked at the same time. Working pressure for these sizes is confirmed per order by HENGHUA engineering, based on the thread size, sealing method and material selected.

Temperature is a material question and is stated here as a material fact. For NBR seals the working range is approximately -30°C to +100°C; for FKM (Viton-type) seals approximately -20°C to +200°C; for EPDM seals approximately -40°C to +120°C. These figures apply to the elastomer-sealed components of a circuit rather than to the metal cone joints of this series. Carbon steel with zinc plating suits general hydraulic service; specify 304 or 316 stainless steel for corrosive or offshore environments.

2.5 Part Number and Dimension Table

The table below is the complete printed size range of the 6J series. All length and hex dimensions are in millimetres.

What each column means

• PART NO. – the HENGHUA part number. The prefix 6J is followed by one size code, and a lock nut option is added as the suffix LN.
• E – the thread of connection 1, printed as diameter x threads per inch in the SAE style, for example 3/4"X16.
• F – the thread of connection 2, in the same notation. In every printed row E and F are identical, so the adapter is equal ended on both sides of the panel.
• A – the end length at the E end, in millimetres, measured from the cone end to the first hex feature.
• B – the longer length recorded from the E end to the far side of the bulkhead section, in millimetres, as marked on the series drawing.
• L – the overall length of the adapter from cone end to cone end, in millimetres. It must be long enough to pass through the panel and leave thread for the bulkhead nut and both tube nuts.
• S1 – the across flats width of the first hex feature on the body, in millimetres.
• S2 – the across flats width of the second hex feature on the body, in millimetres. In every printed row S1 and S2 are equal, so both hexes of this series take the same wrench size.

Thread size and dash chart

The dash code is the size step, and in this series it follows the nominal tube outside diameter in sixteenths of an inch.

Lock nut option. To order the adapter with a lock nut, add the suffix LN after the part number, for example 6J-12LN. The nut and sleeve that complete each tube joint are ordered separately: use nut NB200 with sleeve NB500 for metric tube, and nut NB200 with sleeve NB300 for inch tube.

3. How to Read a 6J Part Number

A 6J part number has two elements, plus an optional suffix: the series prefix, the size code and the LN option.

The prefix 6J identifies the family: a straight JIC male 74° cone bulkhead stud made to SAE J514, with a 74° cone at each end and a bulkhead hex body. A different prefix in the same catalogue identifies a different geometry, such as a straight stud, an elbow, a tee or a female seat version.

The size code is the SAE dash size and follows the nominal tube outside diameter in sixteenths of an inch: 04 is a 1/4″ tube size with a 7/16″x20 thread, 08 is a 1/2″ tube size with a 3/4″x16 thread and 12 is a 3/4″ tube size with a 1.1/16″x12 thread. Because the printed rows are equal ended, one code describes both sides of the panel.

The LN suffix marks the version supplied with a lock nut. Without it, the adapter is supplied as the stud only. If a suffix appears on your drawing, quote the full part number including it.

Worked example: 6J-12LN.

• 6J – straight JIC male 74° cone bulkhead stud, SAE J514.
• 12 – 1.1/16″x12 male 74° cone at both ends, for the 3/4″ tube size.
• LN – supplied with a lock nut.
• From the table: A is 21.9 mm, B is 44.5 mm, L is 78.5 mm and both hexes S1 and S2 are 36 mm, so one 36 mm wrench fits the body and the bulkhead nut.

A buyer ordering 6J-12LN receives a bulkhead stud with a 1.1/16″x12 cone end on each side, a 36 mm bulkhead hex, and a lock nut. The tube nuts and sleeves are still ordered separately, using nut NB200 with sleeve NB500 for metric tube or NB200 with NB300 for inch tube.

4. Installation and Fitment

A bulkhead joint on a JIC 74 degree cone adapter has one extra step compared with a plain stud: the body has to be fixed in the panel before either cone joint is made up. HENGHUA does not publish a single torque figure for the series, because the correct tightening depends on the nut and sleeve fitted, the tube material and the panel material. Follow the nut supplier’s recommendation, or confirm the figure with HENGHUA engineering per order.

Panel preparation. The hole in the panel has to clear the bulkhead thread, and the panel face under the bulkhead nut has to be flat enough for the nut to seat squarely. A body pulled into a distorted panel loads both cones on one side.

Bulkhead nut. Hold the body with the S1 hex on one side of the panel and run the bulkhead nut down on the other side with the S2 hex. Bring the nut up until it clamps the panel, then stop: the nut positions the body, it does not seal anything.

Cone joints. Keep both cones and both mating seats clean and free of nicks. Wipe them with a lint-free cloth and inspect them under good light. Run each tube nut up by hand until it is snug against the cone, then tighten in stages, and never use a pipe extension or an impact tool on a cone joint.

Thread preparation. JIC 74° cone threads are not the sealing element, so do not wrap them with thread tape or use sealant as a leak cure. A light oil on the threads lets the nut run up smoothly.

Reuse policy. The body with undamaged cones can be reused, and the bulkhead nut can be reused if its thread and faces are intact. The tube nuts and sleeves are the wear items, and a cone shows galling or a bright polished band is replaced rather than retightened.

Common fitment errors and their symptoms:

• Mixing a 37° flare with a 74° cone seat. Symptom: the nut runs up but the joint weeps at first pressure.
• Fitting the wrong dash size. Symptom: the nut will not start by hand, or starts and then bottoms out without contact on the cone.
• Leaving the bulkhead nut loose so the body turns. Symptom: the cone joint cannot be tightened and the line rotates with the wrench.
• Reusing a sleeve already compressed on another tube. Symptom: the joint leaks under vibration.

Six-step assembly

1. Confirm the part number against the line list and check that both ends match the mating tube assemblies.
2. Check the panel hole, the panel face and the body thread, and confirm that the adapter passes through far enough to take the bulkhead nut and the tube nut.
3. Inspect both cones and the mating seats for nicks, corrosion and previous overtightening marks.
4. Fit the body in the panel and run the bulkhead nut down until it clamps the panel, holding the body on the S1 hex.
5. Fit the nut and sleeve to each tube, bring each tube square to its cone by hand, then tighten in stages without an extension bar.
6. Pressurise the circuit, check both ends for weeping, and re-check the tightness after the first thermal cycle.

5. Applications and Industries

Application tags for this series: hydraulic systems, water jetting, oil and gas, industrial equipment, construction machinery, agriculture, marine, material handling. A JIC 74 degree cone adapter is specified by its thread size and its panel duty rather than by industry, so one part serves several sectors.

Lines through a wall or frame. This is the defining duty of the 6J adapter. A tube run inside a machine enclosure is brought through the frame and connected to the outside run at one fixed point, so the panel supports the routing load and the line stays organised.

Cab, tank and reservoir walls. A line that leaves a reservoir wall or a machine cab is connected with a bulkhead adapter so the wall carries the transition instead of a hose chafing against the opening.

Repair and replacement. Maintenance crews replace a damaged bulkhead stud on site, because the adapter is the part that wears when a line is repeatedly broken out at a wall. Because the table covers 11 sizes, the replacement is normally drawn from stock.

OEM assembly lines. For production programmes the series is supplied to a drawing-based specification with the material, plating and lock nut option fixed per line.

6. Replacement and Cross-Reference Guide

Cross-reference for this series is organised by standard and sealing method, never by brand. Two hydraulic tube fittings interchange only if the standard, the thread size, the seat angle, the seal type and the bulkhead dimensions all match.

A JIC adapter in this series is a SAE J514 bulkhead stud with a 74° cone at both ends. It is not interchangeable with a JIC 37° flare fitting, because a 37° flare seals on the conical flare face while a 74° cone seals on the wide cone face, and the two seats will not mate. It is also not interchangeable with an ORFS fitting, which seals a flat face against an elastomeric O-ring under SAE J1453, with an NPT fitting, which seals on the thread flanks under ANSI/ASME B1.20.1, or with a SAE O-ring boss stud end to SAE J1926-3 / ISO 11926-3, which seals with an O-ring and a lock nut on a straight thread.

To identify the correct replacement for a 6J adapter, measure three things.

1. Thread. Measure the outside diameter and pitch of the cone end thread: a 3/4″ end measures about 19.0 mm outside diameter with 16 threads per inch. Measure the bulkhead thread too, because two bulkhead adapters with the same cone ends can differ in panel fixing.
2. Seat angle. Use a seat angle gauge or a straight edge against the cone. A 74° cone is wide and shallow; a 37° flare is narrow and steeper. If the angles differ, the parts do not interchange however well the threads match.
3. Seal type. Confirm whether the joint relies on a metal cone, an elastomer O-ring or the thread itself. A 74° cone joint has no O-ring in the sealing path; a part with a captive O-ring or a flat face groove belongs to a different family.

Where the port standard is not SAE J514, a cross standard adapter of the same size is the correct part rather than a forced thread. Record the measurements with the part number so HENGHUA can match a printed size code.

7. Ordering, Packaging and Delivery

To order, give the following information:

• Series code: 6J.
• Full part number, for example 6J-12LN, taken from table 2.5.
• The thread size at both ends, read from the E and F columns.
• Lock nut requirement, expressed as the LN suffix.
• Nut and sleeve requirement, including the tube standard, because these are ordered separately from the adapter.
• Seal material for the elastomer-sealed components in the circuit: NBR, FKM or EPDM.
• Body material and plating, and the quantity and packing format required.

Packaging formats: bulk cartons for line-side consumption, small boxes for distributor shelves and labelled bags for service kits, each labelled with the part number, the thread size and the quantity. Sample orders and first-article parts are available for OEM programmes, including drawing-based manufacture of specials.

Lead time is confirmed per order and depends on size, material, plating, the lock nut option and quantity. As a hydraulic adapter manufacturer and hydraulic adapter supplier, HENGHUA can quote this hydraulic tube fitting, the lock nut, the nut and the sleeve as one matched kit.

8. FAQ

How does a bulkhead adapter work?

A bulkhead adapter carries a hex on one side of a panel and a bulkhead nut on the other, so the panel is clamped between them and the body is fixed in place. The panel carries no pressure; it only positions the body. Both ends then connect independently, from either side of the wall.

What is the difference between JIC 37° flare and ORFS, and which should I use?

A JIC 37° flare joint seals metal-to-metal on a 37° conical flare face under SAE J514. An ORFS joint seals a flat face against an elastomeric O-ring under SAE J1453. Choose the family that matches the port already on the equipment, because the two are not interchangeable. This JIC adapter is on the 74° cone side of SAE J514, so confirm the seat angle before ordering.

Can NPT and BSPT be interchanged?

No. NPT is a 60° taper pipe thread under ANSI/ASME B1.20.1, and BSPT is a 55° taper pipe thread under ISO 7-1. The form, angle and pitch differ, so the two will not seal even when a few threads start by hand. Use the thread the port is machined to, and order a cross standard adapter when the two sides differ.

How do I identify the correct 6J size?

Measure the thread outside diameter and pitch on the mating tube assembly, then read across the E and F columns of table 2.5 for that thread. In this series the two columns are always equal, so one measurement identifies the size. Check the panel hole and the bulkhead thread as well, because the body has to pass through the panel and take the lock nut.

What seal material should I select for my fluid and temperature?

For general mineral hydraulic oil within -30°C to +100°C, NBR is the usual choice. For higher temperatures up to approximately +200°C, or where the fluid attacks NBR, choose FKM (Viton-type). For water, water-glycol and many water-based fluids, EPDM is the option, with a working range of approximately -40°C to +120°C. The cone joint is metal-to-metal, so on a JIC 74 degree cone adapter the seal material applies to the elastomer-sealed parts of the circuit.

How is the working pressure of this adapter determined?

Working pressure is not fixed by the series code. It is governed by the thread size, the wall thickness of the stud and the tube, the sealing method and the material selected, and the panel fixing has to be checked at the same time. Working pressure for these sizes is confirmed per order by HENGHUA engineering, based on the thread size, sealing method and material selected.

What does the LN suffix mean and are the nuts included?

LN marks the version supplied with a lock nut, for example 6J-12LN. The tube nut and sleeve that complete each cone joint are always ordered separately: use nut NB200 with sleeve NB500 for metric tube and nut NB200 with sleeve NB300 for inch tube. Quote the tube standard with the order.

What is the minimum order quantity and can I get samples?

Minimum order quantity depends on the size code, the material, the plating and the lock nut option, so it is confirmed with the quotation rather than published as one figure. Samples and validation parts are available for OEM and distributor evaluation.

Send your requirement to HENGHUA

Send the part number, the thread size, the panel thickness and hole data, the lock nut and tube nut requirement, the material and plating, and the quantity. HENGHUA confirms the match to the printed table, the seal options and the delivery schedule, and quotes the 6J adapter that fits your panel.

Related series in the same family: the 1J adapter (straight) and the 8J adapter (lock nut). Browse the full Hydraulic Adapters range for the complete SAE J514 JIC, NPT, ORFS and ISO 6162 flange families.