Guide to Flaring and Swaging Copper Pipes

Connecting copper tubes can present unexpected challenges, from mismatched sizes to persistent leaks. These issues often stem from insufficient knowledge about two critical techniques: flaring and swaging. These processes modify the tube ends to create secure connections without welding. This guide explores both methods in detail, covering principles, tool selection, and step-by-step procedures.

Tube flaring involves reshaping a copper tube's end into a conical (bell-shaped) opening through applied pressure. This creates a mechanical joint compatible with tapered fittings like valves or connectors, offering weld-free convenience for maintenance or disassembly.

• Flare Geometry: The conical opening typically forms a 45° or 37° angle, determined by industry standards. These angles aren't interchangeable—mismatched angles compromise seal integrity.
• Tool Selection: Lever-style flaring tools dominate the market, featuring a tube clamp and tapered punch. Rotating the handle gradually shapes the tube end, with models available for all standard tube diameters.
• Angle Applications: 45° flares prevail in refrigeration systems, while 37° variants serve aerospace and hydraulic applications exclusively. Always verify angle compatibility between tools and fittings.

Swaging expands tube ends cylindrically to accommodate slip-fit connections, typically sealed through brazing. This permanent joining method reduces fitting requirements while enhancing structural integrity.

• Swage Dimensions: The expanded section's inner diameter slightly exceeds the mating tube's outer diameter, with length optimized for strength and sealing.
• Tool Varieties: Options range from impact swagers (budget-friendly for small jobs) to manual ratcheting models (mid-volume work) and electric units (high-volume production).
• Advantages: Eliminates intermediate fittings, reduces potential leak points, and improves system aesthetics while lowering material costs.

Proper preparation ensures reliable connections:

• Cutting: Use rotary tube cutters for square ends. Avoid compression cutters that distort tube geometry.
• Deburring: Remove all internal/external burrs using dedicated deburring tools or fine-grit files. Burrs compromise seals and damage tooling.

1. Select the correct die size matching the tube's outer diameter
2. Secure the tube with 1/8" protruding (use a coin for reference)
3. Align the punch precisely with the tube axis
4. Apply gradual pressure until full flare formation
5. Inspect for uniform thickness and absence of cracks

Pro Tip: Apply light oil to the punch cone to reduce friction and improve finish quality.

Three primary approaches exist:

• Impact Swaging: Hammer-driven punches for occasional use
• Manual Swaging: Ratchet mechanisms for controlled expansion
• Power Swaging: Electric or pneumatic tools for production environments

1. Immobilize the tube vertically in a vise
2. Select the appropriately sized punch
3. Insert the punch and strike firmly with rotational movements
4. Check diameter frequently with calipers

This innovative technology uses rotational friction to heat and reshape tubes:

• Mechanism: High-speed rotation generates localized heat for precise deformation
• Procedure: Mount in a drill, insert into tube end, and activate for 3-5 seconds
• Benefits: No cold-working stress, consistent results, and rapid operation

1. Match the expander ball to the target inner diameter
2. Insert fully into the tube end
3. Apply gradual pressure while rotating the tool
4. Verify final dimensions with plug gauges

Mastering these techniques empowers professionals to create reliable, leak-free connections across plumbing, HVAC, and industrial applications. Proper tool maintenance and methodical execution yield optimal results regardless of project scale.