A single headed tube is an electric heating element, and due to its long-term use, its maintenance treatment is also necessary to ensure its extended service life. The repair and treatment of blackening of single ended pipes is often the most common maintenance method, which we refer to as blackening treatment. 
Simple steps for blackening treatment of single headed pipes:
The prerequisite for blackening treatment is to maintain the cleanliness and tidiness of the outer surface of the heating tube. If there are impurities on its surface, it will not be conducive to the treatment of blackening.
The first thing B needs to do is to understand the organic matter on the surface, which is called degreasing treatment. Everyone should rest assured that degreasing is easy to achieve. As long as there is degreasing solution available for degreasing processing. And degreasing solution is also easily available on the market. The requirement for degreasing treatment is to maintain a very high alkalinity of the liquid, with a stable pH value of around 13. The time requirement is approximately 30 minutes. After completing this process, the external surface needs to be cleaned to remove impurities that may cause chemical reactions. Cleaning must be done with clean water to ensure a high level of cleanliness on the surface of the heating tube.
After alkaline washing, it needs to be pickled. Because its surface not only contains alkaline organic compounds, but also acidic organic compounds. So acidic cleaning is also very necessary. A pH value of 3 is required for acidity, and the processing time is only about 10 minutes.
The official blackout process will eventually be implemented. A Ph guarantee between 2-4 is sufficient. A time of 10 minutes is sufficient. After processing, proceed with cleaning.
The final step is to dry the single head tube. Drying is done to remove the water adhering to the surface of the single ended pipe. Finally, it's time to apply oil.