Stainless steel pipe plate flange is a kind of accessory that drill a hole slightly larger than the outer diameter of the pipe on the stainless steel circular steel plate, penetrate the pipe into the weld and fix it. In the calculation of the fixed tube sheet, the axial stress of the shell, the axial stress of the heat exchange tube and the pull-out force Q between the heat exchange tube and the tube sheet are calculated according to various working conditions with temperature difference. If one of them can not meet the strength (or stability) conditions, the expansion joint needs to be set. In the strength checking calculation of fixed tube sheet, when the thickness of tube sheet is determined and there is no expansion joint, sometimes the strength of tube sheet is not enough. After the expansion joint is set, the thickness of tube sheet may meet the requirements. At this time, expansion joints can also be set to thin the tube sheet, but it depends on the comprehensive evaluation of material consumption, manufacturing difficulty, safety and economic effect.
U-type expansion joint is commonly used in fixed tubesheet heat exchanger, which has the advantages of compact and simple structure, good compensation and low price.
The accuracy of tubesheet processing, especially the pipe hole spacing, pipe diameter tolerance, perpendicularity and finish, greatly affect the assembly and use performance of the chemical equipment listed above. With the large-scale chemical equipment and power station, the diameter of the tube sheet is becoming larger and larger. The tube sheet with the diameter of 4m-5m is very common. The characteristics of large tubesheet are large number, density, small diameter, depth, high precision and finish.
Purpose:
Tubesheet is widely used in tubular heat exchanger, boiler, pressure vessel, steam turbine, large central air conditioning and other industries.
It is mainly used in chemical vessels, such as tubular heat exchanger, pressure vessel, boiler, condenser, central air conditioning, evaporator, desalination, and plays the role of supporting and fixing the tubular. The material of metal makes it not only has strong rigidity, but also has great heat conduction performance.
The evaluation standard of tube sheet
In the inspection process of tube sheet, the main inspection indexes are hole location, hole tolerance, hole finish, burr, gouging position, etc. for double tube sheet, more attention is paid to hole location in the inspection process, and the hole location matching degree of two tube sheets is very important. Generally, it can be ensured by CNC drilling machine. Compared with thick plates, the perpendicularity of holes above 300 mm is very important. These large-diameter thick plates need more precise tools and equipment. The application of special gantry machining center will become more and more common.
Advanced processing method of tubesheet
In fact, one of the main problems restricting the processing of tubesheet is the problem of equipment. In traditional tubesheet processing, radial drill is the main equipment. Because of its manual operation characteristics, the operation method is relatively fixed, so it is difficult to tap the potential. Although the efficiency can be improved by means of jigs, the fundamental problem can not be solved. Only from the equipment to find a way, can fundamentally solve the problem. In foreign countries, multi axis CNC drilling machine has been widely used in pipe hole processing, instead of radial drilling, CNC plane drilling machine can replace manual marking and drilling, which can greatly improve the processing accuracy and efficiency. In recent years, China has also begun to realize the localization of this kind of drilling machine, but the products of most manufacturers are small (2m ~ 3M) bed and few main shafts (one or two). Large tubesheets cannot be machined. It cannot completely replace imported products. Therefore, for large tubesheets (over 7m) that require high machining accuracy, they can only be processed abroad. However, the imported CNC machine tools are expensive, long installation period and difficult to maintain, which are not necessarily suitable for China 0010010 #39;s national conditions. It is urgent for domestic machine tool manufacturers to produce super large CNC drilling machines to meet the needs of tube sheet manufacturers.
