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| Tubing 101-The Information You'll
Need to Make Your Tubing Selection |
| Knowing what information goes into a tubing
decision gives you the power to work with Superior Tube to determine
exactly which tubing will meet your needs. It's true if you
know what you need, and especially if you're not sure. |
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Here you'll find the resources to help you
define your selection, or refine the information you do have,
so we can work with you on the answers. Use our Tubing
Information Form. |
| A Few Definitions |
When you're talking with us, we want to
be sure we're both using the same terminology. Here are a few
of the basics.
Annealing-Heating and then cooling a material to
soften it and make it less brittle.
As-drawn
Tube-Any tube in any temper other than annealed, normalized,
or heat treated.
Average OD-The average of a
minimum of four micrometer readings, including the high and
low points, equally spaced around the full circumference of
the tube.
Compressive Forming-Shaping a tube
by pressing between rolling forming dies.
Cold
Working-Permanently altering the shape or size of a metal
object by plastic deformation, carried out below the recrystallization
point.
Drawing-Pulling the tube through a die
with or without support of the inside of the tube.
Eccentricity-Frequently referred to as wall runout,
the variation in wall thickness at any one cross section through
the tube is the difference between the center of the circle
formed by the OD and the center of the circle formed by the
ID. It is expressed by the term "TIR" (total Indicator
Reading), which is twice the difference between the center of
the OD and the center of the ID.
Heat Treated-A
tube which has been quenched and tempered or precipitation-hardened.
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ID-Inside diameter.
Light
Wall-Any wall dimension which is less than 3% of the nominal
average OD.
NDT-Non-destructive testing. Methods
include ultrasonic, dye penetrant, and eddy current testing.
Normal Wall-Any wall dimension which is 3% or more of the nominal
average OD.
OD-Outside diameter.
Ovality-Out-of-roundness, or difference between maximum
and minimum dimensions of OD, obtained by careful micrometer
measurements for high and low points at any one section around
the tube. The ovality tolerance is considered to be a total
spread inside which both the maximum OD dimension and minimum
OD dimension must fall.
Straightening-Removing
the bow that can be the result of the forming process.
Tempering-A heat treatment technique for metals and
alloys, most often the toughening of martensitic steel.
Wall Run-out-Half the difference between the maximum wall thickness and minimum wall thickness. Also equal to two times the eccentricity.
WELDRAWN-Superior Tube Company's trademark for
our process of forming tubing from strip. The welded seam has
no flux or metal added, so there is no variation from the analysis
of the strip.
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| Cold Working-The Better Way
to Make Tubing |
At Superior Tube, all of our forming processes
are cold. This has proven a successful approach, for a set of
reasons that crosses the individual forming techniques:
- Better control of nominal dimensions and tolerances
- Better surface finish without additional process
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- More refined grain size, leading to easier fabrication
and forming, higher resistance to chemical attack and corrosion,
higher ductility, and higher fatigue limits
- Higher mechanical strength through multiple forming steps
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| The Ways to Form Tubing |
There are three processes that we use in
making tubing. The choice of technique may have implications
for mechanical properties, cost, and suitability for different
metals.
Compression-The stock tubing is fed through a series
of rolling dies that reduce the tube to the desired dimensions.
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Drawing-Starting with a stock tube
of the desired analysis, the tube is pulled or "drawn"
through a die, often with a mandrel controlling the ID.
Rolling-In this process, the way we make our WELDRAWN
product, a flat strip of desired analysis is rolled into a tubular
shape and the seam welded, without the use of flux or filler
metal. It may then be further shaped using the other processes. |
| To Draw or Compress? |
| The decision between these processes takes
into account several factors. The chart indicates some
of these basic factors, showing which technique has the advantage.
Our engineers will work with you to refine this decision, or
make recommendations that will help you select the process that
best meets your requirements. |
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Compression |
Drawing |
| Dimensional Precision |
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| Finer Grain Size |
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| Grain Orientation |
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| Higher Physical Properties
in the "Cold Worked" Condition |
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| Suitable for Difficult
Alloys |
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| Surface Finish Smoothness
(ID/OD) |
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| Tooling Costs |
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| Volume Application |
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| Wall Consistency |
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| What We’ll Need to Know |
| Our Tubing
Information Form is designed to help you organize information
about your requirement. Fill in as much as you can, as preparation
for discussions with our tubing specialists. They will then
be able use your information to help you make the decision about
the product that will satisfy your need. |
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indicates
the process having the advantage.