Why Coning & Threading Still Matters in High-Pressure Tube Fabrication

Cone and thread connections have stood the test of time because they work. But how they are produced has evolved—and that evolution matters.

Whether you are cutting metal with a waterjet, designing a hydrogen system, or building high-pressure assemblies, the ability to produce reliable, repeatable connections quickly is no longer a luxury, it is a competitive advantage.

What Is a Cone & Thread Connection?

A cone and thread connection is a method of preparing the end of thick-wall tubing so it can seal reliably under extreme pressure.

The process involves:

• Coning: Machining a precise chamfer (cone) on the tube end.
• Threading: Adding threads—often left-handed—to secure the connection.
• Assembly: Using a specialized gland nut to connect the tube to a fitting or manifold.

Once assembled, these connections can withstand tens of thousands of PSI, making them one of the most trusted high-pressure methods available. In fact, this style of connection is widely accepted and, in many cases, required—in U.S. government applications.

Where Are Cone & Thread Connections Used?

Anywhere high-pressure fluid systems exist; you will typically find cone and thread fittings.

Common industries include:

Waterjet Cutting (Metal, Stone, Food Processing)

High-pressure waterjet systems rely on consistent, leak-free connections. Whether cutting stainless steel, granite countertops, plastics, or even poultry, these systems operate at extremely high pressures making connection integrity critical.

Energy, Hydrogen & High-Pressure Gas Systems

Hydrogen and other high-pressure gas systems demand precision sealing to prevent leaks. Cone and thread connections provide repeatable, reliable performance in these environments.

Aerospace & Defense

Government-approved connection methods are essential. Cone and thread fittings are often specified due to their proven ability to perform under extreme pressure and vibration.

Industrial High-Pressure Fluid Systems

From test systems to hydraulic applications, any system pushing pressure limits benefits from a connection that minimizes variability.

The Problem: Traditional Coning & Threading Is Slow and Inconsistent

Despite how critical these connections are, many shops still produce them using outdated methods:

1. Engine Lathe Method

• Tube is manually set up.
• Cone is machined.
• Threads are single-point cut or applied with a die.
• Result: Accurate, but slow and operator-dependent

2. Hand Tool Method (Drills + Vises)

• Tube is clamped in a vise.
• Handheld tools perform coning and threading.
• Result: Inconsistent quality, several minutes per part, high operator variability

These manual processes can create:

• Cycle time inefficiencies.
• Operator skill dependency
• Inconsistent sealing performance

The Advantage of a Dedicated Coning & Threading Machine

A purpose-built coning and threading machine, such as the CNT15 Coning & Threading Machine for High-Pressure Tubing, can change the process entirely. You can eliminate multiple manual steps and reduce cycle time.

• Load the tube.
• Automatic clamp
• Cone + thread completed.
• Unclamp

What does this mean in practice:

What Engineers and Manufacturers Should Consider

When designing or evaluating a high-pressure tubing process, a few key factors come into play:

1. Connection Reliability

Cone and thread connections are proven to perform under extreme pressure, making them a go-to standard.

2. Process Control

Manual processes introduce variability. Automated coning and threading eliminate that inconsistency.

3. Cycle Time

Faster processing directly impacts labor cost, throughput, and delivery timelines.

4. Material Considerations

Stainless steel and specialty alloys are expensive. Scrap or rework due to poor connections is costly.

5. Repeatability Across Operators

Standardizing the process removes reliance on individual skill levels.