Pricipals of Tube Rolling

Formulae to work out a Finished ID.

Principals of tube rolling Rolling and beading tubes

Principals of tube rolling are the art of reducing a tube wall by compressing the OD of the tube against a fixed container such as rolling tubes into a tube sheet. To assure a proper tube joint causing a gas-tight seal, the tube wall must be reduced by a predetermined percentage. The following chart can help determine the correct tube wall reduction and assist in Principals of tube rolling. 

This Chart shows a typical 2.0"OD x 10 BWG (0.134")

Principals of Tube Rolling - Determine the following:
  1. (A) First Determine the Hole size.
  2. (B) Then Determine the tube outside diameter.
  3. (C) Subtract the tube outside diameter from the tube hole dimension.
  4. (D) With a good quality tube gauge, determine the ID of the tube before rolling.
  5. (E) By adding the dimension found in “D” to the clearance between the tube OD and the tube hole, you will then know the tube’s inside diameter at metal to metal contact.
  6. (F) Roll the tube to what you feel is a good tube joint. This example was rolled and then the ID of the tube was checked with the tube gauge.
  7. (G) By subtracting “E” from the rolled diameter you determine the actual amount of expansion (tube wall reduction) on the inside diameter of the tube. This can be converted to a % of wall reduction by dividing the actual wall thickness (“B minus D”)  in the amount of the roll.
Follow the link above for Expander specifications found in individual pdf's
Tube Sheet Hole
Tube Outer Diameter OD
Clearance (A-B)
Tube Inner Diameter ID
Clearance
Inner Diameter at Metal to Metal
13% of 0.134 x 2
Inner Diameter at Metal to Metal
Expanded Tube Inner Diameter

2.010″

2.000″

0.010″

1.732″

+0.010″

1.742″

0.035″

1.742″

1.777″

Tube Wall Reduction Percentages based on Material

Application

Non Ferrous tubes in surface condensers.

Steel tubes in heat exchangers.

Soft Copper, Cupro Nickel and aluminum tubes in heat exchangers.

Boiler tubes.

Tube Wall Reduction

3% to 4%

5% to 10%

8% to 12%

12% to 14%