Tubesheets are perforated plates used to support and insulate pipes in heat exchangers, boilers, and filters. They can be made of various metals or composites and are coated with insulation and corrosion protection. Tubesheets are used in pairs in heat transfer applications and individually in filters. The design process is complex and precise, with computer-aided design and CNC machines used for drilling. Tubesheets are bolted to flanges inside the shell, forming two closed chambers. Sacrificial or galvanic anodes can be attached to the surface for further protection.
A tubesheet is a perforated plate, sheet, or bulkhead with a pattern of holes designed to accept pipes or tubes. These sheets are used to support and insulate pipes in heat exchangers and boilers or to support filter elements. Depending on the application, a tube sheet can be made of various metals or resin or plastic composites. A sheet metal pipe can be covered with a coating material that acts as a corrosion barrier and insulator and can also be equipped with a galvanic anode. Tubesheets can be used in pairs in heat transfer applications or individually when supporting elements in a filter.
Perhaps the best known use of tubesheets is as support elements in heat exchangers and boilers. These devices consist of a tightly packed arrangement of thin-walled tubes located within a closed tubular shell. The tubes are supported at both ends by sheets which are perforated in a predetermined pattern to allow the ends of the tubes to pass through the sheet. The ends of the tubes entering the tubesheet are expanded to lock them in place and form a seal.
The arrangement of the tubes forms a unit contained between the tubesheets. The tubesheets are then bolted to the flanges inside the shell. The shell extends beyond each tube sheet and is sealed, thereby forming two closed chambers on the non-tube ends of the tube sheets. This creates an arrangement where the exchanger consists of two separate end chambers joined by tubes running through an isolated space between the tube sheets. The heated fluid is then passed from one end chamber to the other through the tubes, where the cold fluid in the cavity between the tubesheets absorbs the heat energy.
The design of the tubesheets is a fairly precise and complex process; it is necessary to establish the exact number of tubes and calculate a pattern of holes to distribute them uniformly on the surface of the tubesheet. Large heat exchangers can have several thousand tubes running through them arranged in precisely calculated groups or bundles. Sheet metal design and manufacturing is now largely automated with computer-aided design (CAD) software that performs the calculations and tube sheet drilling done on computer numerically controlled (CNC) machines.
The tube sheets used in heat exchangers and boilers are often coated with an insulating layer which also serves to protect against corrosion. To further protect the tubesheet from rust, a sacrificial or galvanic anode can also be attached to the surface of the tubesheet. Tubesheets are also used on cartridge filter devices to support individual filter elements. They are similar in design to the high-heat boiler varieties, except that they are usually made of resin or plastic composites and are usually used as single units. There are usually fewer tubes involved in a filter application, although the tubesheet design still needs to be carefully calculated to ensure optimum performance.
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