Boiler tubes replacement

 

Boiler tubes replacement  is the work of partial or total replacement of its flame tubes. That is, the pipes through which the flue gases exiting towards the chimney pass.

The boiler flame tubes, although in most cases they are seamless tubes, either due to chemical corrosion (corrosion from free oxygen) or due to poor cooling are destroyed. Point leaks (holes) or extensive damage (pitting corrosion) can appear.

At a rate of up to 10%, these tubes can be pluged at their two ends, now forming part of the water chamber of the boiler. In a greater percentage, both due to the reduced power of the boiler and due to its uneven thermal loading, they must be replaced with new ones.

The replacement can be either partial (replacement of only the leaking tubes ) or total (replacement of all the tubes). This is decided based on the findings of the inspection of all the tubes and the assessment of the damages they show.

The replacement of a tube consists of the following basic tasks:

- Removal of the welding material between the tube and the front boiler tube sheet

- Removal of the welding material between the tube and the rear boiler tube sheet

- Extraction of the tube from the boiler

- Milling of the boiler tube sheets holes

- Insertion of new tube with prepared ends (paint removing, cleaning)

- Mechanical expansion of the tube ends on the boiler tube sheets

- Welding of the tube ends  on the boiler tubes sheets

Even nowadays, in the vast majority of cases, both for the removal of the material of the welds and for the extraction of the tubes , oxygen flame cutting is used. However, in the first case this destroys the boiler tube sheets  by removing parts of them and at the same time overheats them, while in the second case a naked flame (oxygen flame cutting ) is used with the operator inside the water chamber of the boiler (high risk).

Our company, always guided by the safe execution of quality maintenance work, has invested in special mechanical equipment with the use of which all the above problems are eliminated.

The removal of the welding material is done with a portable air cutter. A portable cutting tool that operates with compressed air. By using suitable cutting tools, only the material of the old weld is removed, while at the same time a milling is created in the boiler tube sheet  in order for the new welding to take place.

The boiler tube sheet is not overheated by the use of a high temperature flame cutting and no extra material is removed from it other than the material of the old weld.

The extraction of the tubes is done using a special hydraulic extractor that works with a high-pressure pneumatic oil pump (pulling force 45 tn). The operator does not need to work inside the water chamber of the boiler using an Oxygen flame cutting.

In this way, tubes replacement  takes place faster, safer and without causing damage to the tubes sheets of the boiler.