Thermite Welding (Cable To Pipeline)

Presently, we can see a widely spread construction of gas, oil pipeline benches. When speaking about electrochemical protection for these constructions. Here a reliable contact of cable with the pipeline wall which provides the contact between a protected object and equipment is considered to be the main factor for reliable cathodic protection. Thermite cable welding is an easy and highly reliable solution to serve this purpose. termitnay_svarka-min Thermite welding is a welding method when thermite is used to heat metal. Thermites are powder mixtures with aluminum or magnesium and oxides of other metals (copper, copper and aluminum alloys). Thermite welding is widely used in different spheres of industry and construction:
    • in case the rods with large diameters should be joined;
    • in construction and repair works of the the pipelines with different pressure to provide cathodic protection.
In many cases the metallic elements can be reliably joined with this type of welding.

Process description

Traditionally, thermite welding involved the usage of thermite powder. The mixture is ignited with a pyrocartridge or with electric ignition means, it starts burning at 1,300°С. Fire scale (one of welding elements) melts. This results in a welded seam. The ignition is a very rapid process, it spreads over the whole mixture, and in 20 - 30 seconds a thermite (thermite crayon) is completely consumed. It is burnt in a fire-resistant mold. So, the process is based on regenerative properties of aluminum or magnesium which gets in contact with metals covered with oxide film and develops exothermic reaction. Heat emission results in a melted bath or weld seam.

Features of thermite welding

    This welding has a number of advantages:
  • reliable joints;
  • available both for industrial and household purposes;
  • small dimensions;
  • energy independent.
However, there is one drawback - a need in preparatory works. The technology is not new, this method has been known for more than half a century in the industry. Quite resently this method has been widely and frequently applied to in manufacturing.

How to weld cables?


1 step

Prepare the area for works. Dig a hole of the required size for safe and comfortable work of a welder.

2 step

Prepare a pipeline. Remove an insulation coating from the pipe, then clean it thoroughly from all impurities. A welding place is filed bright and cleaned with a cloth moistened in petrol (acetone).

3 step

Prepare and weld the leads with copper thermite mixtures and graphite melting molds (TF). Insulation is removed from a cable side at the distance of 120 mm. a holder is put at a welding place. The end of the cable enters the pouring chamber of the used melting mold or graphite holder.

4 step

Check the quality of the materials and prepare equipment. Shake the package for welding the leads before usage. Open it right before installation. When opened, the content of the package fills the central channel of a reusable melting mold with a measuring cup which is also delivered. The mixture should be poured in 2 steps, between them the layer should be compacted. There a thermocrayon or a soldering welding rod is placed as well.

5 step

Decide how to ignite thermomixture (with a thermomatch or an ignition transmission cord).

6 step

Weld the leads.

7 step

Finish the process. The welded place should be cooled for at least 5 minutes. A melting mold is taken off, slag is removed from welding area of the cable. Finally, check the weld seam size and the quality of the joints.