Metric 74 Degree Cone Flared Nut Adapter NB200-Q (GB/T 5647 Flared Tube Nut)

Why This Metric 74 Degree Cone Flared Nut Adapter NB200-Q Passes the Compliance Gate

The metric 74 degree cone flared nut adapter NB200-Q is the union nut of the GB/T 5647 flared tube system. It is not a stand-alone connector: the nut works as one half of a pair, and together with the matching NB500-Q flared sleeve it clamps a 74 degree flared tube end against the 74 degree cone of an adapter body, which is what actually produces the seal.

Buyers who treat this nut as a simple fastener run into trouble. The nut carries the thread that engages the adapter body, the sleeve is what contacts the flared tube, and the seal is formed by the flare being pressed onto the cone. The nut never touches the fluid path, and a nut on its own cannot seal anything.

Three facts matter when ordering:

• The nut is selected by the tube outside diameter and by the thread of the mating adapter body. The published table lists both, so a 5 mm tube takes the M10X1 nut and a 28 mm tube takes the M39X2 nut.
• The matching sleeve must be ordered from the same tube size row of the GB/T 5646 sleeve table; NB200-22Q belongs with NB500-14Q, and no other combination is dimensionally correct.
• Two rows share a tube reference, NB200-30Q and NB200-30EQ, because M30X1.5 and M30X2 adapter bodies are both used with a 20 mm tube.

Core Advantages

1. Published pairing. Every nut row lists its thread and tube size, so the sleeve can be matched without guesswork.
2. Full size range. Thirteen nut sizes from M10X1 on a 5 mm tube to M39X2 on 28 mm.
3. Hard-wearing thread. Rolled or cut metric thread with a protective plated finish to resist galling during repeated assembly.
4. Supplied with the sleeve on request. Order nut and sleeve together and the flared tube joint arrives complete in one shipment.
5. Batch traceability. Heat number, production batch and inspection records are tied to each carton.
6. OEM marking. Customer part numbers and lot codes can be laser marked on request.

Especificaciones técnicas

What Is a Metric 74 Degree Cone Flared Nut Adapter?

The metric 74 degree cone flared nut adapter NB200-Q is the hex union nut of the GB/T 5647 flared tube system, a 74 degree cone flaring system in which the tube end is flared and then clamped by a sleeve and nut onto an adapter cone. The GB/T 5647 nut is dimensionally paired with the GB/T 5646 sleeve, and the sealing surface of the joint is the flared tube end on the cone, never the nut.

Two points are often misunderstood:

Dimensional Data

Full Dimension Table (Part Number Matrix)

All dimensions are in millimetres and are reproduced exactly as published for this series.

Thread Size and Dash Chart

Material and Heat Treatment

The series drawing states no material grade, so the following describes typical production and is confirmed on the purchase order.

Working Pressure and Operating Envelope

The published drawing carries no pressure column, so no pressure rating is claimed for this series. Working pressure of a finished flared tube joint is governed by the port standard together with the tube and sleeve grade selected, and the finished assembly is only as strong as its weakest member.

• A 74 degree flared joint is limited by the tube wall and by flare quality as much as by the nut.
• Data sheets referenced to the flared tube system standards (GB/T 5646 and GB/T 5647) can be supplied on request.
• Each batch is inspected and packed with batch records as part of the standard HENGHUA fitting workflow.
• For safety-critical circuits, rate the assembly from the lowest rated element: tube, flare, sleeve, nut or adapter body.

Rango de temperatura

A typical service window for a steel flared joint with a metal-to-metal cone seal is -40 degrees C to +120 degrees C. The real limit is set by the tube and by the connected hose or adapter body, not by the nut. Outside that window, specify the complete joint material set and confirm with our engineering desk.

How to Read the Part Number Matrix

The metric 74 degree cone flared nut adapter NB200-Q is coded with a family block, a size number and a thread suffix.

NB200 identifies the GB/T 5647 flared tube nut family, the number is the thread size in millimetres, Q marks the 74 degree cone flared system, and the E suffix in NB200-30EQ marks the 2 mm pitch variant.

Selection and Ordering

Selection Checklist / Decision Table

Confirm the following points before ordering the metric 74 degree cone flared nut adapter NB200-Q.

Cross Reference Service

Send a photograph of the worn nut with the thread outside diameter, the pitch gauge result and the tube outside diameter, and we will identify the correct row and its matching sleeve free of charge, normally within 24 hours. We do not copy or re-label another company’s brand; we match the interface and the drawing.

Packaging and Logistics

Individual poly bags with size labels or bulk bags per size, carton marking with batch and heat number, mixed-size consolidation in one shipment, and air freight or courier for urgent requirements. Nuts and sleeves can be supplied as matched kits on request, and material certificates travel with the goods when requested.

Installation and Fitment Guide

Step-by-Step Assembly

1. Cut the tube square. A flared joint starts with a square cut; an angled cut produces an uneven flare and a leak path.
2. Deburr and, if required, anneal. Remove internal and external burrs, and anneal hard tube ends where the standard or drawing requires it before flaring.
3. Flare the tube end to 74 degrees. Use a flaring tool that produces the correct cone angle and flare diameter for the tube size; a cracked or split flare must be cut off and re-made.
4. Slide the nut, then the sleeve, onto the tube. Fit the nut first, then the sleeve, in the orientation shown in the drawing, before the flare is presented to the adapter cone.
5. Seat the flare on the adapter cone. Push the tube forward until the flare contacts the 74 degree cone squarely.
6. Tighten the nut to the published torque for the thread size, holding the adapter body with a second wrench, then leak test at working pressure.

Torque and Sealing Notes

• Use the torque figure published for the thread size and material; under-torque leaves the flare unseated and over-torque crushes the tube end.
• The seal is made by the flared tube end on the 74 degree cone. No sealant is used on the flare, and sealant on the thread does not repair an unseated flare.
• The nut must run down freely by hand before final torque; a nut that binds indicates a cross thread or the wrong pitch.
• Renew the sleeve, and inspect the flare, each time the joint is opened.

Installation Warnings

• ✔ Confirm the flare angle is 74 degrees and the flare is free of cracks.
• ✔ Check that the nut and the sleeve come from the same tube size row.
• ✔ Hold the adapter body with a backing wrench while tightening the nut.
• ✔ Re-test at working pressure after any re-torque.
• ❌ Never assemble the joint without the sleeve; a nut alone cannot seal a flared tube.
• ❌ Never fit the sleeve reversed or use a sleeve from another tube size.
• ❌ Never re-use a sleeve that has been crushed or a flare that has been distorted.
• ❌ Never use a 60 degree or 24 degree cone adapter body with this nut and sleeve pair.

Applications and Industries

The metric 74 degree cone flared nut adapter NB200-Q is used wherever flared tube joints must be renewed or specified as a matched pair with the sleeve.

Industry tags: hydraulics, tube fabrication, repair workshops, test benches, mobile machinery, marine, mining, plant maintenance.

Common Fitting Faults to Avoid

OEM Customization and Quality Traceability

HENGHUA produces hydraulic adapters, flared tube components and complete hose assemblies alongside its Globhose hose programme, so the metric 74 degree cone flared nut adapter NB200-Q can be supplied alone or as a matched nut and sleeve kit.

• Laser marking and private labelling with customer logo, part number and lot code.
• Custom surface treatment including trivalent zinc and Zn-Ni.
• Drawing or sample based production, with quotation typically within 24 hours.
• Trazabilidad de los lotes from heat number to carton label.
• Testing and documentation: material certificates and BV or SGS inspection on request.

FAQ

Q: Can the NB200-Q nut be used without the sleeve? A: No. The nut only provides clamping force. The NB500-Q sleeve is what contacts the flared tube and presses it onto the 74 degree cone, so a nut alone cannot seal a flared tube joint.

Q: How do I know which sleeve goes with which nut? A: Match the tube outside diameter and thread from the pairing table above, for example NB200-22Q with NB500-14Q on a 14 mm tube. Never mix rows.

Q: What is the difference between NB200-30Q and NB200-30EQ? A: Both are for a 20 mm tube. NB200-30Q has an M30X1.5 thread while NB200-30EQ has an M30X2 thread, so the correct one depends on the thread of the adapter body.

Q: Is this nut compatible with a JIS 60 degree cone system? A: No. This is a 74 degree cone flared system to GB/T 5647, and the JIS system uses a 60 degree cone per JIS B 8363, so the two cones cannot be clamped together.

Q: What pressure can the joint hold? A: The drawing carries no pressure column, so no rating is claimed. The limit of a flared joint depends on the tube wall, the flare quality and the sleeve, and the assembly is only as strong as its weakest member.

Q: What material is the nut made from? A: Typical production is carbon steel with trivalent zinc plating; stainless steel 304 or 316L is available on request. Confirm the grade on the purchase order.

Q: How much torque should be applied? A: Use the published torque value for the thread size and tube material, holding the adapter body with a second wrench. Request the torque table for your size with the order.

Q: Where can I buy the metric 74 degree cone flared nut adapter NB200-Q with matching sleeves? A: Order the nut and sleeve together by PART NO., for example NB200-22Q with NB500-14Q, and state the material or coating and quantity. Quotations are answered within 24 hours and standard sizes ship in 7 day batches.

Solicitar un presupuesto

Send the tube outside diameter, the thread of the mating adapter body, the matching sleeve PART NO. if known, the material or coating and the quantity, and we will confirm the correct row of the metric 74 degree cone flared nut adapter NB200-Q table, normally within 24 hours. If you are replacing an unmarked nut, send a photograph with the thread and tube measurements and we will identify both the nut and its sleeve free of charge.

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