If you are planning to pull out the old rusty tubes and install newer ones from the boiler, it’s time for you to search for the tube expanders. We present you all about the boiler tube expanders. Just check it out..!!!
Methods Of Tube Expansion:
In the process of tube expansion, the tubes are joined together by expanding the tube inside the tube sheet. Hydraulic expansion is one of the most widely used methods of tube expansion in boilers. In this method, high pressure is applied inside the tube, which results in a perfect joint. Check out the two major processes in it.
• The direct expansion system is a simpler process. Calculated hydraulic pressure is applied internally at the expanded area.
• The other process is the explosive expansion of the tubes. As the name suggests, an explosive charge is placed inside the tube. On detonation, immense pressure is generated which results in the joining of the two tubes. The outside area of the tubes is sealed to avoid the damage.
Mechanical rolling is another predominantly used rolling process. A set of hardened rolls is used to exert the predetermined radial force at the point of contact between the tube and rolls. The two major processes of mechanical rolling are listed below:
• In the process of linear swaging, the tube to be joined is made to suspend from a wire line. It is then expanded by forcing a mandrel into it.
• Another process of mechanical rolling is the rotary swaging. In this process a cone, which has external rollers is employed to carry out the expansion process. The rotation of the cone while pulling creates the necessary pressure to expand the tube.
Major Causes Of Tube Leaks:
• A perfect fit can be achieved only after the predetermined expansion of the tubes. When the tube is not expanded to the fullest, it fails to make a contact with the tube sheets. This results in leakage.
• In contrast to the above case, if the tube is expanded excessively, it can cause serious damage to the vessel. It is firmly believed that it is better to under roll than to over roll. This statement shows how drastic could be the effects of over rolling.
• The tube holes have to be well prepared before performing the operation on them. Improper preparation makes it too difficult to expand the tubes. The smoother the finish of tube sheets, the better is the expanding process.
• Another major problem faced while dealing with thicker tube sheets is due to their thermal expansions. The temperatures produced during this process expand the tube and tube sheets. Make sure to clean the surfaces of the tubes and tube sheets.
• Drill and ream the tube holes to achieve desired dimensions. After preparation, make sure to coat them with rust preventive compounds. Clear the tube ends from foreign materials, if any. You need to be extremely careful when you have to force a tube. If you have any plans of using a hammer, we suggest you to try springing rather than hammering.
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