Metric Male 74° Cone Bulkhead Adapter 6Q — 74° Cone Through-Panel Adapter

Why This Metric Male 74° Cone Bulkhead Adapter Passes the Compliance Gate

A bulkhead adapter carries two loads at once: the hydraulic pressure inside the bore and the mechanical load of the panel, the tube run and the vibration around it. If the stem is short, the locknut runs out of thread before it clamps; if the clamping shoulder is not square to the stem axis, the panel is loaded unevenly and the tube run starts to walk. Every 6Q metric male 74° cone bulkhead adapter is machined with both 74° cones cut in the same setup as their threads, the panel thread and the clamping shoulders checked for squareness, the stem length verified against the drawing, and the whole part dimensionally inspected before packing. Cones are measured for included angle and seat diameter on a profile projector, threads gauged go / no-go.

The fitting is a straight through-panel adapter with a metric male 74° cone connection on each side and the body passing through the panel, clamped by a locknut. The catalogue shows four versions of the same body: 6Q (the plain adapter), 6Q-LN (with lock nut), 6Q-RN (with sleeve and nut) and 6Q-LN/RN (with both).

Core Advantages

• Panel support and pressure containment in one part. The tube run is anchored at the bulkhead instead of hanging on its end connections.
• Two 74° cone ends. Both sides use the same wide metal cone seat, so the same tube ends and the same tools are used on either side of the panel.
• Vibration isolation. The panel carries the mass of the tube run and the vibration that would otherwise be transmitted into a port thread.
• Clean service split. The circuit can be opened on one side of the panel without disturbing anything on the other side.
• Four variants, one body family. Plain, lock-nut, sleeve-and-nut and combined versions cover different panel constructions and different tube ends.

Technical Specifications

What Is a 74° Cone Bulkhead Adapter?

It is a straight adapter whose body passes through a panel, bulkhead plate or bracket and is clamped on the far side by a locknut. Both connections are metric male 74° cone ends. The fluid path stays inside the body, so the panel joint is a mechanical clamp rather than a pressure seal — the panel does not have to be a sealing surface, only clean, square and strong enough.

The Variants — 6Q, 6Q-LN, 6Q-RN and 6Q-LN/RN

If you are replacing a part already in service, identify which of the four you are holding before ordering: the overall length L differs between them because the sleeve and nut add to the make-off side.

Cone Geometry — 74°, 60° and 37° Are Not Interchangeable

Both ends here are metric 74° cones:

Different included angles put the contact band at a different diameter and a different axial position, so a mixed pair makes edge or line contact, passes a cold static test and weeps at working temperature. Confirm the seat angle on both sides of the panel.

Dimensional Data

In the drawing, E and F are the threads of the two 74° cone ends, D1, D2 the tube outside diameters they serve, A the end length from the end face to the body hex, B the through-panel stem length between the body shoulders, L the overall length, S1, S2 the across-flats hexes of the two ends and S3, S4 the across-flats hexes of the locknut and the sleeve nut.

B is the dimension that decides whether the installation works: it has to be long enough for the panel, the washer and the locknut to sit on the stem with full thread engagement, and it must leave the tube ends clear of the panel on both sides. On panel work, measure the panel thickness and the locknut height and compare them with B and L rather than trusting the old part.

Full Dimension Table (Part Number Matrix)

Values as published in the HENGHUA catalogue drawing. Dimensions in millimetres.

Thread Size and Dash Chart

Material and Heat Treatment

Carbon steel bodies, machined from bar or forged, hardened according to pressure class and plated in trivalent chromium or zinc-nickel; the locknut is plated in the same batch as its body so that the pair does not gall. Stainless 304 / 316L is available to order, as is an insulating washer where a steel body passes through an aluminium panel.

Working Pressure and Operating Envelope

Pressure is contained by the body and the two 74° cone joints; the panel joint carries only mechanical load. A 4:1 burst ratio is typical of the body. The panel must be strong enough to take the clamping load and stiff enough that the tube run does not move under vibration.

Temperature Range

−40 °C to +120 °C for standard components; up to +200 °C with FKM in associated seals. The 74° cone joints have no elastomer in the sealing path; the panel material and washer should be selected for the same temperature band.

How to Read the Part Number Matrix

6Q-22 reads: family 6Q (metric male 74° cone bulkhead adapter), size 22 = a 14 mm tube port with M22×1.5 on both ends. The suffixes identify the supplied hardware: LN for lock nut, RN for sleeve and nut, and LN/RN for both — for example 6Q-22-LN/RN. Quote the variant, not just the size, when cross-referencing an OEM part number.

Selection and Ordering

Selection Checklist / Decision Table

Cross Reference Service

Send the OEM number, the tube OD, the panel thickness and a photograph of the assembly. We identify the variant (LN, RN, LN/RN), verify the stem length against the panel and return a mapped part number with the washer and locknut listed.

Packaging and Logistics

Supplied with the locknut and/or sleeve and nut as ordered; threads protected, bagged, cartoned and palletised. Certificates and inspection reports referenced to the heat number. Air, sea and express shipping available.

Installation and Fitment Guide

Step-by-Step Assembly

1. Verify the panel hole diameter against the body thread and the panel thickness against the stem length B. Deburr both sides of the hole.
2. Check the panel is square and rigid; a flexible panel will move the tube run and load both cone joints.
3. Confirm both ends are 74° cone seats — 60° or 37° seats will not seal against them.
4. Insert the adapter through the hole from the working side.
5. Fit the washer (and the insulating washer where required), then run the locknut on by hand.
6. Set the flow direction first: once the locknut is tight, the body position is fixed.
7. Hold the body hex and tighten the locknut to its specified torque.
8. Make off the tube connections on both sides with their sleeves and nuts, holding the body so the panel clamping load is not disturbed.
9. Re-check the locknut and both cone joints after the first thermal cycle.

Torque and Sealing Notes

The locknut torque is a clamping value, not a sealing value: enough to hold the body against vibration, not enough to crush the panel or stretch the stem thread. A washer spreads the clamp load and protects the panel face. Both 74° cone joints are metal-to-metal, torqued separately, with no tape and no compound. Three different torque values may apply to one installation — locknut, sleeve nut and cone — and they must not be confused.

Installation Warnings

• Never tighten the locknut by turning the body or a tube connection; hold the body hex.
• Do not use the bulkhead joint as a pressure seal or expect it to seal a damaged panel face.
• Do not mix 74°, 60°, 37° and 24° cone components.
• Do not shorten the stem or add spacers that reduce thread engagement below the specified number of turns.
• Do not over-tighten a locknut on an aluminium or composite panel without a load-spreading washer.

Applications and Industries

Bulkhead adapters are used where tube runs cross chassis members and machine frames, on machine-tool cabinets and guarding, on hydraulic power units with panel-mounted manifolds, on shipboard systems passing bulkheads, on cranes, mining and agricultural machinery, and on test benches where the tube run must be fixed relative to the instrumentation. The metric male 74° cone bulkhead adapter is the part that turns a loose 74° cone tube run into a supported one.

OEM Customization and Quality Traceability

Custom stem lengths, panel threads, locknut and washer combinations, special hex, alternative materials and plating are produced to drawing. Incoming material verification, first-article inspection, ring-gauge checks on the panel thread, squareness checks on the clamping shoulders, cone angle measurement, proof pressure testing on sample lots and final inspection are recorded against the order, with EN 10204 3.1 certificates on request.

FAQ

Does the bulkhead joint seal the pressure? No. The fluid path is inside the body; the locknut only clamps the body to the panel.

Which variant do I need? LN for a lock nut, RN for a sleeve and nut, LN/RN for both. Identify the variant before ordering — the lengths differ.

What panel hole do I need? One sized to the body thread, with the panel thickness within the stem length B.

Are both ends the same? Yes, both connections are metric male 74° cone ends of the same size in the standard range.

Can the adapter be re-oriented after tightening? Only by releasing the locknut. Set the direction before final torque.

Do I need a washer? Recommended on soft panels, and on aluminium to spread the load and avoid galvanic contact.

Request a Quote

Send the part number and variant, the tube OD, the panel thickness and material, the quantity and the working pressure. We will confirm the stem length, the locknut and the washer, and quote with the inspection documentation included.

Related products in this range: metric male 74° cone adapter 1Q · metric 74° cone to ISO 6149-3 adapter 1QH · 74° cone adapter with bonded seal 1QL · 74° cone to BSPT male adapter 1QT-SP · metric male 74° cone plug adapter 4Q.

Browse the full Hydraulic Adapters range for the complete family, or contact us to request a quote, mill test reports, and samples.