Thermal Welding
Auxiliary equipment of cathodic protection / thermal welding systems:
Thermal welding is commonly used to connect the cable to the structure under cathodic protection. Therefore, the following equipment is needed to perform this process:
A) Thermal welding mold: The material of thermal welding mold is graphite and according to the size of the cable and the structural shape of the structure, they are offered in different types. Such as: flat bottom, semi-round, etc. (in the case of pipes, the diameter of the pipe determines the type of welding mold). According to the graphite material of the welding mold and the conditions of use, the frequency of thermal welding is different, and usually up to 100 thermal welds can be used optimally.
b) Welding powder: Welding powder consists of sulfur, copper powder and several other materials. According to the type of mold and their size, they are offered in different weight sizes such as: 25, 32, 45, etc. Some acne powders also have a wick.
c) Flakes: Flakes are used to connect the cable to the structure under protection and cover the welding area.
d) Cleaning tool: After each welding, the thermal welding mold must be cleaned (the effects left by the sulfur explosion), which is done by the cleaning tool of a wire brush, a special spatula, safety gloves and a mask.
e) Combustion lighter: It is used to ignite welding powder.
Set of thermal welding equipment
The steps of thermal welding are as follows:
To perform safe and solid thermal welding, empty the surroundings of the structure from debris and soil from excavation.
According to the size of the cable and table number one, separate a square (usually 10 x 10 cm) of the cover for thermal welding from the pipe.
Clean the surface of the pipe with a wire brush, then degrease the desired area with a suitable solvent.
In order to strengthen the welding point, make several grooves on the pipe with a suitable tool.
Remove the cable cover according to the size of the cable and the welding mold (usually 7 cm) from the cable and put it in the welding place, then place the welding mold on the cable, after placing the flakes inside the welding mold, welding powder with Pour the appropriate weight on the scale and close the lid of the mold after putting the wick inside the welding powder.
Light the welding powder with a special lighter.
After the explosion of sulfur and the freezing of the welding melt, in order to ensure the mechanical strength of the joint, hit the weld with a hammer.
After completing the above steps and cooling the weld, proceed with the thermal weld test according to the standard (the said test is performed by hitting a half-kilogram hammer on the weld area).
Then fix the cable to the pipe with a clamp or insulating tape.
Thermal welding steps
Technical requirements of the thermal welding process:
Due to the explosion of sulfur and the possibility of molten material spreading, safety equipment such as glasses, gloves, etc. should be used during welding.
The distance between two thermal welds should not be less than 15 cm.
It is not allowed to perform welding on the previously damaged welding site.
Since, if moisture is absorbed, the powder will not function properly, it is recommended to store them in dry environments.
Avoid doing welding in places where the pipe has high humidity, and to do welding, the desired place must be completely dry.
In environments with flammable gas, before welding, the gas in the environment must be discharged and a fire extinguisher must be available on site.
In order to connect the cable to the stainless steel structure, you must weld a piece of carbon steel metal to the stainless steel pipe at the welding location and perform the welding process as in the previous steps.
For welding on pipes with a thickness of less than 78.4 mm, the following method is used (in this regard, prepare a two-part clamp according to the size of the pipe. Connect the cable to the clamp by welding. Put two screws on Install the clamp as shown below.Hold the clamp on the pipe (this was done by adjusting the two screws installed on it).
