Boiler Swaged Tubes

Product Description

Boiler Swaged Tubes Explained

Swaged tubes in a boiler are tubes that have been mechanically reduced in diameter at one or both ends to allow a snug fit into headers, drums, or other tubes of smaller diameter. Swaging is done to ensure tight mechanical joints, promote better weld connections, or allow for expansion fitting.

What Are Swaged Boiler Tubes?

• Swaging is a metal forming process that reduces the outer diameter (OD) of a tube by cold or hot mechanical deformation.

• In boilers, swaged tube ends are used when the tube needs to connect to a drum hole or header that is smaller in diameter than the tube body.

• Its a common practice in water-tube boilers, especially in superheater, economizer, and water wall tubes.

Purpose of Swaging:

1. Join different tube sizes (e.g., 2" tube swaged down to fit a 1.5" header)

2. Ease of installation in tight or restricted boiler spaces

3. Provide smooth internal transitions to reduce turbulence

4. Prepare tube ends for welding, expansion, or rolling into drums or headers

Swaging Process:

 Tube Materials:

Swaging can be performed on most boiler tube materials:

• Carbon steel (e.g., SA-210 Gr A1)

• Alloy steel (e.g., T11, T22)

• Stainless steel (e.g., TP304, TP316)

• The material must maintain mechanical integrity after deformation.

 Inspection & Quality Control:

• Dimensional checks (OD, taper, wall thickness)

• Visual inspection for cracks or scoring

• Dye penetrant or magnetic particle testing for surface defects

• Hardness tests (especially after cold swaging of hardened steels)

Best Practices:

• Use proper lubrication to reduce surface damage during swaging

• Allow post-forming heat treatment if required (for alloy steels)

• Ensure uniform wall thickness after swaging

• Select the correct die angle and taper for smooth transition

Typical Dimensions:

• Original Tube OD: 1.5" to 3"

• Swaged End OD: Reduced by 1/8" to 1/2", depending on fit

• Swage Length: Usually 2" to 6", or custom per spec