Steel Tube Production Process
Indiana Tube Corporation is your complete source for high quality, small diameter, single wall, welded, low carbon steel tube. With tube sizes ranging from 5/32" to 11/2" Outside Diameters and Wall Thicknesses ranging from 0.020" to 0.095".
Steel Tube Production Process
Raw Material Input:
Steel is paid off of an uncoiler and fed into a strip
reserve. A strip reserve is utilized during the
butt-welding process, which is the means to which the
trailing end of a steel mult is joined to the leading end of
a new steel mult. All butt-welds are cut out of the tube
and scrapped.
Raw Material: Low Carbon Steel, Aluminum Killed Drawing Quality
Grade: 1006 - 1008
Cleaning and Drying Process:
All strip passes
through an in-line strip wash process which removes oil,
dirt, and smut from the strip. The strip wash process is
essential in meeting with customer and industry residue
requirements. The cleaning process includes a wash tank,
rinse tank and strip dryer.
Wash Tank: The wash tank cleanses the strip by means of a alkali soap and water solution as well as rotating brushes, which scrub the steel strip as it passes through the wash tank.
Rinse Tank: The rinse tank assures that all wash solution is removed from the steel strip.
Strip Dryer: The strip dryer aids in the drying of the strip after having been washed and rinsed.
Forming and Welding:
After the strip passes through the cleaning/drying process
it enters into the forming/welding process. This process
forms the strip into a tubular shape and then welds the tube
by means of high frequency induction welding. Due to the
welding process a weld bead is formed on the outside and
inside of the tube. The outer weld bead is removed to allow
for a smooth outer surface as where the inside weld bead
remains untouched and becomes an integral part of the tube.
During the welding operation the weld temperature is
continually monitored through the use of a infrared
pyrometer to insure the tubing is welded within a
temperature range capable of providing a complete and
thorough weld. The welding/forming process involves edge
conditioning, forming, welding, and scarfing operations.
Edge Conditioner: The edge conditioner trims the strip edges to insure they are square and smooth. This edge preparation is essential for proper welding.
Forming Mill: The steel strip is roll formed from the flat strip stock into the tube. This process incorporates a series of progressive rolls that gently form the strip into the tube.
Welding: High Frequency Induction Welding is utilized by Indiana Tube Corporation for the welding of tube. Indiana Tube Corporation currently has five tube mills, two of which are welding tube at approximately 0.500” (12.7mm) outside diameter, two at approximately 0.750” (19.05mm) outside diameter and the fifth is welding the tube to the manufactured tube size. The formed tube is passed through a high frequency induction coil to heat the edges of the formed tube. It then goes through a set of squeeze rolls which forge the hot edges of the tube together.
Scarfing: Scarfing is the process in which the outside weld bead is removed (cut) from the tube. The necessity of this process is to insure a smooth outer surface of the tube.
Reducing/Rounding Operation:
Four of the five tube mills use a cold roll reduction
process to size the outside diameter and wall thickness of
the tube. This process incorporates the use of a set of
in-line idler and drive rolls. Each set of rolls has a
radius ground in them which is smaller than the radius of
the preceding rolls. By gradually reducing the rolls’ radii
through this process, the outside diameter of the tube is
reduced. The wall thickness of the tube is controlled by
the amount of elongation done as the tube travels through
this process.
The fifth tube mill is producing the tube to the correct size (welding to size) and the finished tube is sent through a series of rolls only to insure the finished tube is of the correct OD and within tolerance. The wall thickness of the tube produced on this tube mill is achieved by the use of the proper strip thickness.
Reducing Mill: Cold roll reduction is used to size the tube to the proper outside diameter and wall thickness. In this process, a series of horizontal rolls (idler rolls) and vertical rolls (drive rolls) are used to gradually work the tube down (reduce) to the proper size. While the tube is being reduced down in outside diameter it is also being elongated. The wall thickness is being controlled by means of the elongation to the tube during the reducing operation.
Rounding Operation: Our fifth tube mill is welding the tube to the proper size, however, the tube is still sent through a minimal series of horizontal and vertical rolls after welding to insure the tube is of the proper OD and within the necessary tolerances to meet with the specification in which the tube is being produced. After which the tube goes through eddy current testing, as listed below, and then a rust inhibitor applied. The tube is cut to the proper length and the tube ends wire brush de-burred. At this point the tube is then packaged for shipment.
Eddy Current Testing: Eddy current test equipment is used after the reducing operation. This equipment introduces the tube to a magnetic field. During normal tube production this magnetic field does not fluctuate, however, should a defect present itself, a fluctuation in the magnetic field will occur causing an alarm to sound and the tube to be marked within the area of the defect. This area of tube will then be removed and scrapped.
Annealing:
Indiana Tube Corporation uses in-line high frequency annealing on four of our
five tube mills, this provides for a consistent rockwell
throughout the tube coils as well as from coil to coil.
Due to the reduction process, the tube is work hardened. The annealing process relieves the work hardening and brings the tubing into a rockwell range that allows the tube to be straightened, bent, flared, beaded, etc. An inert or nitrogen gas is injected into the annealing process to insure the tube does not oxidize during the annealing process.
Annealers: In-line, high-frequency annealers bring the tube up in temperature for proper annealing.
Run-out: The run-out allows the tube to gradually cool after being brought to temperature for annealing. This gradual cooling is essential to the annealing process.
Quench Tank: The final step within the annealing process is to quench the tube. The quench is to insure the tubing is at approximately ambient temperature so that it can be handled. The quench of the tube is done through the use of water pumped over the tube as it goes through the quench tank.
Plating, Coiling Process:
Indiana Tube Corporation has the ability to provide tube with a copper flash
coating having a thickness of
≤
0.1 microns. This plating is applied through the use of an
electro plating process and then the tube is coiled into
coils ready for shipment or further in-house processing.
Plating System: The plating system is a series of bulkheads with the appropriate solutions being pumped up over the tube to clean and etch the tube, rinse any excess cleaning/etching solution off, copper plate the tube, rinse excess plating solution off, and apply a rust inhibiting solution to the tube.
Coiling: Indiana Tube Corporation provides tube coils off of four of our five tube mills. Our standard tube coils have a 28” coil ID, 42” coil OD and have a average weight of approximately 800 pounds. Coiled tubing pays off in a clockwise direction when viewed looking down on the tube coil as it lies in a horizontal position.
Packaging: Samples are taken from each tube coil and the tube is weighed and packaged. All test results (outside diameter, wall thickness, rockwell) are recorded on a coil ticket as well as coil weight, coil footage, production date, shift, and machine number and the ticket is then affixed to the tube coil. The package receives a box label which has the individual coil weight and footage recorded on it as well as total weight, total footage, shift, date, machine, box, and item identity. All test results are also held in long-term storage at Indiana Tube Corporation through the use of a computer file.
Indiana Tube Corporation
2100 Lexington Avenue
Evansville, IN 47720
Phone: 812-424-9028 Fax: 812-424-0340
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Corporation is a subsidiary of
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Harman
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