AS

310101c Tube Bending and Tube Joining

Tube Bending and Tube Joining ILM 310101c

Objectives

  • Identify different types and sizes of tube and tube fittings

  • Understand common tools and techniques for tube joining

  • Learn common tools and techniques for tube bending

  • Calculate bending lengths for various tube configurations and angles

  • Identify hazards related to tube fitting selection and installation

Overview of Tubing

  • Tubing: A long hollow cylinder for moving fluids or protecting cables

  • Uses of tubing:

    1. Mechanical tube

    2. Pressure tube

    3. General purpose tube

Types of Tubes

Mechanical Tube

  • Available in various shapes and sizes

  • Not designed for internal pressure

  • Used mainly for construction and protection

Pressure Tube

  • Designed to carry fluids and gases

  • In instrumentation, used for instrument air to actuate instruments

  • Impulse lines connect measuring instruments

  • Common materials include:

    1. Copper

    2. Steel

    3. Thermoplastic

Copper Tube Specifics

  • Primarily used in plumbing and HVAC systems

  • Standards set by ASTM for 99% pure copper

  • Six standard types identified by color coding:

    • Type K: Green - Use: Domestic Water Service, Distribution, Fire Protection

    • Type L: Blue - Use: Similar to Type K but different applications

    • Type M: Red - Similar to Type K but lighter applications

    • DWV: Yellow - For Drain, Waste, and Vent

    • ACR: Blue - For Air Conditioning and Refrigeration

    • OXY/MED: Green/Blue - For Medical Gases, Compressed Air

Sizing and Types of Tube

  • Size determined by OD (Outside Diameter)

  • Temper types:

    • Drawn Temper: Hard or rigid

    • Annealed Temper: Soft and flexible

Tube Fittings

  • Types of fittings:

    1. Flare fittings

    2. Flareless fittings

    3. Soler fittings

Flare Fittings

  • Consists of nut, sleeve, and body with a flared end

  • Requires a flaring tool for preparation

Flareless Fittings

  • Consist of a ferrule with sharp leading edges

  • Seal made between ferrule and body;

    • They may develop leaks over time

Mechanical Grip Flareless Fittings

  • Two ferrule design:

    • Back ferrule grips tubing as the front ferrule polishes it

    • Produces a secondary seal

Push-in Fittings

  • Use O-ring for gripping the tubing

  • Requires tubing softer than the O-ring material

Proper Fitting Tightening

  • Hand-tighten the nut then 1 ¼ turn

  • Check proper torque and tubing position

  • Use a gap gauge (NO GO Gauge)

Solder and Soldering

  • Solder: A metal alloy melting between 90-450 °C

  • Used to join metallic surfaces through soldering

  • Alloys melting above 450 °C termed brazing

  • Commonly now lead-free; can contain flux

Copper Tube Soldering

  • Tin/lead solders available with varying tin concentrations (5-70%)

  • Higher tin concentration increases tensile and shear strengths

  • Common alloys:

    • 50/50 Tin/Lead melts at 215 °C

    • 60/40 Tin/Lead melts at 188 °C

Soldering Equipment

  • Torch: Small propane for general, air acetylene for higher temperatures

  • Solder: Typically tin/lead alloy

Flux

  • Cleaning agent to remove oxidation during soldering

  • Prevents oxide layer formation during heating

Steps for a Good Solder Joint

  1. Cut tube to length & deburr

  2. Clean tube ends; apply flux

  3. Clean fittings; apply flux

  4. Assemble and support

  5. Heat uniformly and solder

  6. Allow to cool & clean excess flux

Capillary Action

  • Definition: Liquid’s ability to flow against gravity in narrow spaces due to intermolecular forces

  • Important in soldering to ensure filler penetrates joints

Self Test and Assignment

  • Review the material covered for practical understanding and application.