Where are pressure vessel forgings mainly applied?
In the calculation of fixed pressure vessel forgings, among the axial stress of the shell, the axial stress of the heat exchange tubes, and the tensile force q between the heat exchange tubes and the tube sheet calculated under various working conditions with temperature differences, if any one cannot meet the strength (or stability) conditions, an expansion joint needs to be set up. In the strength verification calculation of fixed pressure vessels, when the thickness of the pressure vessel is determined and no expansion joint is set, sometimes the strength of the pressure vessel is insufficient. After setting an expansion joint, the thickness of the tube sheet may meet the requirements. At this point, expansion joints can also be set up to thin the tube sheet, but the decision should be made based on a comprehensive assessment of material consumption, manufacturing difficulty, safety and economic benefits.
With the large-scale development of chemical equipment and power stations, the diameter of pressure vessel forgings is also getting larger and larger. It is very common for the diameter of Yali pile to be 4m-5m to expire. The characteristics of large pressure vessel forgings are a large number of dense pipe holes, small hole diameters, deep holes, and high requirements for precision and surface finish.
Pressure vessel forgings are widely used in industries such as tubular heat exchangers, boilers, pressure vessels, steam turbines, and large central air conditioning systems.
It is mainly used in chemical containers, such as tubular heat exchangers, pressure vessels, boilers, condensers, central air conditioners, evaporators, and seawater desalination, to support and fix the tubes. The metal material not only makes it highly rigid but also has excellent thermal conductivity.
Depending on the different usage environments, different materials are used. Generally, Q345R container plates are used. For instance, for first and second-level pressure vessels where there is no corrosive medium flowing, carbon steel composite plates can be used. In environments with strong acids, high pressure, high temperature, nuclear energy, etc., corrosion-resistant materials such as stainless steel, 16manganese, and titanium alloy are needed. The application of new synthetic materials has brought new vitality to tube sheet products.
Tube sheets used for Class III and IV pressure vessels require relatively high precision. The traditional hole processing method is to mark with a fitter and drill holes with a radial drill. With the large-scale development of chemical containers, the diameter of tube sheets is constantly increasing and their thickness is gradually thickening. The processing of tube sheets has also introduced numerical control technology, and it is common to use numerical control drilling machines to guide holes in combination with swing arm drills for hole processing. The use of machining centers for high-efficiency and high-precision hole processing has gradually been accepted by some large enterprises. The demand for large and thick tube sheets in the fields of nuclear power, seawater desalination, and central air conditioning heat exchangers is showing an increasing trend.
During the inspection process of pressure vessels, the main inspection indicators are hole position, hole diameter tolerance, inner surface finish of the hole, presence or absence of burrs, groove position, etc. For double tube sheets, more attention is paid to the hole position during the inspection process. The fit degree of the hole positions of the two tube sheets is very important. Generally, a CNC drilling machine can be used to ensure this. Compared with thick plates, for holes larger than 300mm, the verticality of the holes is very important. These large-diameter thick plates require more precise tools and equipment. The application of specially designed gantry machining centers will become increasingly common.
