Tube Expanding is the process by which the tube wall is reduced by compressing the outer diameter of the tube against a fixed container. It can be done easily by keeping tubes into tube sheets. There is specified data to determine the correct tube wall reduction. Tubes are seated tightly whose expansion is somehow impossible manually as it is expanded so as to manufacture heat exchangers for high-pressure steam generators, Food and Pharmaceutical processing systems, Boilers for conventional power generation and Condensers. So, it is very important to decide the best method and tube expansion system for tube expanding. There are several factors for the determination of dimensions, thickness and application of force must be taken as prior so as to expand the tube in a better way.
There is a requirement of tube expansion tools for proper expansion and durability of the tubes. There are various types of tube expansion systems. Some commonly used tube expansion systems are:
- Hydraulic Tube expansion system
- Electric Tube expansion system
- Sugar Mill Tube expansion system
- Torque Controlled Tube expansion system
- Radiator Tube expansion system and others.
There are various accessories like Rolling drives, Torque controllers, Voltage stabilizer, Suspension system etc. are used. By the expansion of the tube inside the tube sheet, swaging of the tube gives the clear data about the space between the two components is always forced closed.
Tube Expansion Methods
- Hydraulic Expansion: It is the latest expansion method, also known as hydro-swaging. It is the more effective method than roller expansion for high-pressure steam generators. In this method, expansion pressures are applied uniformly, tube after tube, which ensures the consistent joints throughout the tube sheet.
- Explosive Expansion: It is done when tubes sheets are sealed by welding. It is used for variation in the thickness of tubes. It is the more expensive way of tube expansion than hydraulic expansion.
- Mechanical Rolling: It is the process in which one roller expands tubes into grooved holes which lead the tube metal extrudes into the grooves. However, this process may cause tube-end fatigue, depending upon the frequency and amplitude of the stresses applied by the rollers.
Major Causes of Tube Leaks
Common causes of tube rolling leakage are under-rolling, over-rolling, improper preparation of tube sheets and differential thermal expansion. Improper expansion can lead to serious difficulties for the manufacturers and repair servicemen. It is important to set the torque of rolling devices. All the dimension should be kept in mind during tube expansion.
The wall dimension can be reduced and increased anytime with proper care. There are specified factors of specific materials like brass, copper, stainless steel, titanium, etc. It is the fact that harder the material, the less wall reduction is required to obtain a tube joint. It is very important to check the quality of the equipment required for tube expansion. There are many manufacturers who produce machines for tube expansion with technological advancements and machinery introduction. Thus, you can select any of them according to your needs.
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