Welded Tubes… Comprehensive overview
Nowadays, approximately there is no home without gas tubes, we see uses of tubes around us even in our furniture.
One of the basic long steel products are welded tubes that entered widely in industries, construction and machinery.
Welded tubes are manufactured from prime steel or secondary steel sheets or stripes to different specifications and standards to produce different qualities, sizes and shapes and each product finds its perfect application in industries or construction works.
What are welded tubes?
Welded tubes are long hollow steel products that are used mainly to convey materials from one location to another.
These tubes are available in many forms and shapes giving them a wide range of applications in industries and construction.
Welded tubes production process:
In general, the tube production process starts by casting the raw steel to a workable starting form like steel billet or flat strip. After that two distinct methods are applied which result in welded tubes or seamless tubes.
Seamless tubes are produced by stretching the billets by heat, while welded tubes are produced by joining the edges of flat stripes together and welding them.
Today, four different welding processes are used to making tubes:
❖ High frequency welding:
Two edges of steel are welded using an electromagnetic field that results in a very strong joint close to the strength of original steel. Most steel mills use this method for welding because it produces a high quality weld.
There are two types of high frequency welding:
● High Frequency Induction Welding: the weld current is transmitted to the steel through a work coil that does not contact the tube. The electrical current is induced in the tube through magnetic fields that surround it. This method eliminates welding marks and reduces the preparation needed when changing tube size.
- High Frequency Contact Welding: the weld current is transmitted to the steel through contacts that ride on the strip. The weld power is applied directly to the tube.
This process is more electrically efficient than the former one which makes it well-suited to large diameter and high wall thickness tube production.
❖ Electric Resistance Welding (ERW) or low frequency welding:
A flat steel sheet is cold-formed to a reeled shape. Then a rotating copper electrode produces a current that passes between the two edges of the tube to heat the steel to a point at which the edges are forced together to form a bond without using welding filler material.
This process is suitable for small diameters since the copper electrodes touch the tube edges and heat them so that they can be welded.
❖ Gas tungsten arc welding (GTAW):
Also known as tungsten inert gas (TIG) welding, this process uses a non-consumable tungsten electrode to produce the weld. Usually a bare metal rod is added from an external source as filler material. Weld pool area shielding is obtained from a gas or gas mixture, usually helium, argon, or a combination of the two.
This process can produce top quality welds and it is best suited to weld thin sections of stainless steel and light metals.
❖ Laser welding:
This process uses a laser to join edges of a steel tube. The resulting product has greater flexibility than a GTAW product. Laser welding process is frequently used in high volume applications using automation, like the automotive industry.
Welded tubes VS seamless tubes:
As their names indicate, the difference lies in the manufacturing method. Seamless tubes don’t have a welding line. They are produced from oblong circular molds that are hollowed by a piercing mill.
This process increases the molds length by twenty times to form a seamless tube shape. After that cold rolling or cold drawing is applied to complete tube shaping.
Welded steel tubes are produced by roll forming strips or sheets of stainless steel into a tube shape and then welding the edges longitudinally.
Similar to seamless tubes, welded tubes can also be drawn to produce a finer weld seam with better surface finishes and tighter tolerances.
Welded tubes have some benefits over seamless ones:
The most important advantage is cost-efficiency since the welded tubes manufacturing process is simpler and cheaper than seamless tubes.
In addition, welded tubes are more readily available in long lengths than seamless tubes.
When selecting between welded or seamless tubes, they should be compliant with your project specifications and suitable to the conditions in which the tubes will be used.
Applications of welded tubes:
The distinguishing features of welded tubes like rust resistance, excellent high-temperature resistance and cost-efficiency give them a large variety of uses in following areas:
- Architectural applications.
- Engineering applications.
- Transportation of various flammable and inflammable liquids and gases for over miles and miles.
- Automotive industry.
- Manufacturing the various joints like the tees, elbows, reducers etc.
- Food and beverage industry.
- Marine industry.
- Pharmaceutical industry and Hypodermic needles.
- Pumps lines.
Welded Tubes shapes:
Welded tubes are measured by their outside diameter and wall thickness.
Different diameters, sizes and wall thicknesses are available of each shape to suit diverse applications.
Prime steel tubes and secondary steel tubes are available in three shapes:
❖ Rounded welded tubes:
Have a shape of a long hollow cylinder. Round tubes are used widely in gas and fuel stations, in construction and transportation.
Round tube has a higher resistance to both flex and torsion twisting than other shapes for a given weight.
❖ Rectangular welded tubes:
Have a shape of a long hollow rod with a rectangular cross-section.
Rectangular tubes are used for an abundance of structural and fabrication projects where increased strength and superior corrosion resistance is required, such as architectural structuring, petrochemical and water treatment.
❖ Square welded tubes:
Have a shape of a long hollow rod with a square cross-section.
Square tubes are commonly used in railing along staircases, and also for structures of buildings and a wide variety of other applications.
Welded tubes from Exanvil Gmbh:
Our company imports the three shapes of welded tubes fitting your need of high quality tubes and your project at competitive prices.
Tubes are cut and modified to meet your requirements and best suit your application.