
How to choose a CNC vertical lathe
2025-05-09
When purchasing a CNC vertical lathe, in addition to its basic required functions and basic components, one should also consider the selection of optional parts, functions and accessories. The selection of accessories for vertical CNC lathes has also developed many accessories to improve processing quality and operational reliability, such as automatic measuring devices, contact probes and corresponding measurement software, tool length and wear detection, and CNC vertical lathe thermal deformation compensation software, etc. The principle for choosing these accessories is to ensure reliable operation and not blindly pursue novelty.
The functions and accessories of CNC vertical lathes
When choosing the functions of the numerical control system, practicality should be the main consideration. It is not necessary to select too many. For the equipment included in the batch production line, the simpler the better. For machine tools with multi-variety and small-batch production methods, the selection of programming functions should be strengthened.
The selection principle is: configuration, giving full play to the short-term and long-term benefits of the main unit, and comprehensive consideration. For those whose prices do not increase much but bring a lot of convenience to use, they should be fully equipped as much as possible.
The configuration plan simplifies the function of programming the numerical control system. A separate automatic programming machine and communication interface with the numerical control system are configured. All program processing is completed on the programming machine in advance, and then it takes a few minutes to send it into the numerical control system. This can further increase the operating rate of the machine tool.
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Three methods for selecting pressure vessel heat exchangers
2025-05-09
There are methods and techniques for selecting pressure vessel heat exchangers. Let's take a look at three methods for choosing pressure vessel heat exchangers below.
The plate type or corrugated type should be determined according to the actual needs of the heat exchange occasion. For cases with large flow rates and small pressure drops, plates with low resistance should be selected; conversely, plates with high resistance should be chosen. Based on the fluid pressure and temperature, determine whether to choose the detachable type or the brazed type. When determining the plate type, it is not advisable to choose those with a single plate area that is too small, as this may lead to an excessive number of plates, a low flow rate between the plates, and a low heat transfer coefficient. Special attention should be paid to larger heat exchangers.
For the design and selection of plate heat exchangers, there are generally certain pressure drop requirements, so verification should be carried out. If the pressure drop of the check valve exceeds the allowable pressure drop, the design and selection calculation should be redone until the process requirements are met.
Heat exchanger flow refers to a group of parallel flow channels in which the medium flows in the same direction in a plate heat exchanger. In a flow-channel plate heat exchanger, the medium flow channels are composed of two adjacent plates. Under normal circumstances, several flow channels are connected in parallel or in series, forming different combinations of cold and hot medium channels. The flow combination form should be determined based on the calculation of heat exchange and fluid resistance when the process conditions are met. The convective heat transfer coefficients of the cold and hot water channels should be equal or similar to achieve a good heat exchange effect. Although the flow rates between the plates of plate heat exchangers are different, the average flow rate is still used in heat exchange and fluid resistance calculations.
The above content is about three ways to choose pressure vessel heat exchangers. We hope it will be helpful to you. Lushen Pressure Vessels will serve you wholeheartedly and look forward to your visit.
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Several Issues on the Design and Manufacture of Pressure Vessels
2025-05-09
“There is a lot of knowledge about the design and manufacture of pressure vessels, covering a wide range of aspects. Let's share the relevant issues together with Xinyuan Chemical Machinery.”
There is a lot of knowledge about the design and manufacture of pressure vessels, covering a wide range of aspects. Let's share the relevant issues together with Xinyuan Chemical Machinery.
What is working pressure in the design and manufacture of pressure vessels? What is calculated pressure? What is design pressure?
Working pressure refers to the maximum pressure that the top of the container should be able to achieve under normal working conditions. Calculated pressure refers to the pressure (including the static pressure of the liquid column) used to determine the thickness of the component at a certain design temperature. When the static pressure of the liquid column borne by the component is less than 5% of the design pressure, it can be ignored. Design pressure refers to the maximum pressure set at the top of the container, which, together with the corresponding design temperature, serves as the design load condition. Its value should not be lower than the working pressure. In the design and manufacture of pressure vessels, it is called calculated pressure. What are the differences between design pressure and calculated pressure in the design and manufacture of pressure vessels, and how are they determined?
The design pressure in the design and manufacture of pressure vessels mainly targets each cavity of the vessel. It serves as a crucial basis for vessel inspection requirements, determination of test pressure, selection of materials, classification, and manufacturing proposals. It is also the primary basis for calculating the pressure of each pressure-bearing component of the vessel. The design pressure of each chamber of the liquefied gas tanker is determined based on the bursting pressure or working pressure of its rupture disc, the opening pressure of the safety valve, etc. The design pressure must not be lower than the working pressure. When a safety relief device is installed, it must not be lower than the bursting pressure of the rupture disc or the opening pressure of the safety valve. The calculation of pressure is mainly aimed at the various pressure-bearing components of the container, and is only used to determine the thickness required for the stability and rigidity of the container and the strength that each pressure-bearing component meets.
The calculated pressure of each pressure-bearing component of the container is determined based on the design pressure of each cavity of the container and the static pressure of the liquid column acting on it separately and in combination. For the pressure-bearing components in multi-chamber containers that are subjected to multi-chamber pressure, the calculated pressure should be determined based on the possible situations that may occur during production operations. For example, when determining the calculated pressure of the heat exchanger tube sheet, the situations where the tube side pressure acts alone, the shell side pressure acts alone, and they act together should be taken into consideration. When determining the calculated pressure of the pressure-bearing elements surrounded by the jacket on the inner container in a jacketed container, the situations where the inner container pressure acts alone, the jacket pressure acts alone, and they act together should be taken into account. At the same time, their stability under the jacket test pressure should also be considered. For single-chamber containers, when there is liquid in the medium, the calculated pressure of the pressure-bearing element subjected to the static pressure of the liquid column is the design pressure of the container plus the static pressure of the liquid column. When the medium is all gas, the calculated pressure of each pressure-bearing component on the container is the design pressure of the container.
Pressure vessel design and manufacturing license level:
Class A is classified as A1: ultra-high pressure vessels, high pressure vessels (single-layer, multi-layer);
A2: The third category of low and medium pressure vessels;
A3: Spherical container
A4: Non-metallic pressure vessels.
Class C is divided into C1: Railway tank cars;
C2: Automobile tank trucks, long tube trailers;
C3: Tank container.
Class D is divided into D1: Class I pressure vessels;
D2: The second type of pressure vessel.
SAD grade refers to the stress analysis design of pressure vessels.
The third category of pressure vessels shall be classified as such if they meet any of the following conditions:
High-pressure vessel
Medium-pressure vessels (only for media with extremely and highly hazardous toxicity levels);
Medium-pressure storage containers (only for flammable or moderately hazardous media with a pV product greater than or equal to 10MPa) 'm3);'
Medium-pressure reaction vessels (only for flammable or moderately toxic media with a pV product greater than or equal to 0.5Pa?) 'm3);'
Low-pressure vessels (only for media with extremely and highly hazardous toxicity levels, and the product is greater than or equal to 0.2MPa?) 'm3);'
High-pressure and medium-pressure shell-and-tube waste heat boilers
Medium-pressure glass-lined pressure vessel
Pressure vessels made of materials with a higher strength grade (referring to the lower limit of the tensile strength specified value in the corresponding standard being greater than or equal to 540MPa);
Mobile pressure vessels, including railway tank cars (with medium being liquefied gas or cryogenic liquid), tank trucks [liquefied gas transport (semi-trailer) cars, cryogenic liquid transport (semi-trailer) cars, permanent gas transport (semi-trailer) cars] and tank containers (with medium being liquefied gas or cryogenic liquid), etc.
Spherical storage tanks (with a volume of 50 cubic meters or more) Cryogenic liquid storage containers (with a volume greater than 5 cubic meters).
Cryogenic liquid storage containers (with a volume greater than 5 cubic meters)
2. For the second category of pressure vessels, any of the following conditions shall be classified as a second category pressure vessel:
Medium-pressure vessel
Low-pressure vessels (only for media with extremely and highly hazardous toxicity levels);
Low-pressure reaction vessels and low-pressure storage vessels (only for flammable media or media with moderate toxicity);
Low-pressure shell and tube waste heat boiler
Low-pressure glass-lined pressure vessel.
3. Class I pressure vessels: Low-pressure vessels other than those specified above are classified as Class I pressure vessels.
Classification and grading of pressure pipelines?
Answer: Classification and grading of pressure pipelines
By pressure:
1. The pressure of low-pressure pipeline engineering is less than 1.6MPa;
2. The pressure of medium-pressure pipeline engineering is 1.6-6.4MPa.
3. The pressure of high-pressure pipeline engineering is 6.4-10MPa.
4. The pressure of ultra-high pressure pipeline engineering is 10-20 mpa.
Pressure pipelines are classified as:
1) Long-distance pipelines are classified as GA type, and their grades are as follows:
1) Long-distance pipelines that meet one of the following conditions are classified as GAl grade:
(1) Pipelines for transporting toxic, flammable and explosive gas media with a design pressure P > 1.6 MPa;
(2) Pipelines for transporting toxic, flammable or explosive liquid media, with a transportation distance (the transportation distance refers to the direct distance between the production site, storage depot and users on the pipeline used for transporting commercial media) of no less than 200 kilometers and a nominal diameter DN of no less than 300mm.
(3) Pipelines for transporting slurry media with a transportation distance of no less than 50 kilometers and a nominal diameter DN of no less than 150mm.
2) Long-distance pipeline foot GA2 grade that meets one of the following conditions.
(1) Pipelines for transporting toxic, flammable and explosive gas media with a design pressure P≤ 1.6 PMa;
(2) Pipelines outside the scope of GAl(2);
(3) Pipelines outside the scope of GAl(3).
Ii. The common passageways are classified as GB class, and the level classification is as follows:
GBl: Gas Pipeline
GB2: Thermal pipelines.
Iii. Industrial pipelines are classified as GC, and the level classification is as follows:
Industrial pipelines that meet any of the following conditions are classified as GC1 grade:
(1) Pipelines transporting media with extremely hazardous toxicity as stipulated in GB5044 'Classification of Hazardous Levels of Occupational Exposure to Toxic Substances';
(2) Pipelines transporting flammable gases of Class A or B or flammable liquids of Class A as stipulated in GB50160 'Code for Fire Protection Design of Petrochemical Enterprises' and GBJl6 'Code for Fire Protection Design of Buildings', with a design pressure P≥ 4.0 MPa;
(3) Pipelines for transporting flammable and toxic fluid media, with a design pressure P≥ 4.0 MPa and a design temperature ≥400℃;
(4) Pipelines for transporting fluid media with a design pressure P≥ 10.0 MPa.
2) Industrial pipelines that meet any of the following conditions are classified as GC2 grade:
Pipelines transporting flammable gases of Class A or B or flammable liquids of Class A as stipulated in GB50160 'Code for Fire Protection Design of Petrochemical Enterprises' and GBJl6 'Code for Fire Protection Design of Buildings', with a design pressure P < 4.0 MPa;
(2) Pipelines for transporting flammable and toxic fluid media, with a design pressure P < 4.0 MPa and a design temperature ≥400℃;
(3) Pipelines for transporting non-flammable and non-toxic fluid media, with a design pressure P < 10MPa and a design temperature ≥400℃; (4) Pipelines for transporting fluid media with a design pressure P < 10MPa and a design temperature < 400℃.
3) GC2 grade pipelines that meet any of the following conditions are classified as GC3 grade:
(1) Pipelines for transporting flammable and toxic fluid media with a design pressure P < 1.0 MPa and a design temperature < 400℃; (2) Pipelines for transporting non-flammable and non-toxic fluid media, with a design pressure P < 4.0 MPa and a design temperature < 400℃.
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The future development prospects of pressure vessels
2025-05-09
Pressure vessels are a kind of equipment with a very wide range of applications. In various fields such as petrochemicals, energy, scientific research, and military industry, there is no shortage of pressure vessel products. With the development of economic globalization, the circulation of pressure vessel products in the international market is becoming increasingly frequent. Today, we will introduce to you some development direction issues of pressure vessels. Pressure vessels are generally composed of six major parts: the cylinder body, the head, the flange, the sealing element, the opening and connecting pipe, and the support. In addition, it is equipped with safety devices, meters and internal components that perform different production process functions. Due to reasons such as sealing, pressure-bearing capacity and medium, pressure vessels are prone to explosion, combustion and fire, which can endanger the safety of personnel, equipment and property and pollute the environment. Therefore, all countries around the world list it as an important product for supervision and inspection. The supervision and inspection as well as technical testing are carried out by the specialized institutions designated by the state in accordance with the laws, regulations and standards stipulated by the state.
Joining the WTO is a great opportunity and challenge for China's pressure vessel industry. It is an important prerequisite for participating in international competition and a standardization work in line with international standards. At present, the application of advanced remanufacturing technology based on information technology and new materials technology in the design and production of pressure vessels in the process industry field will have a great development, especially in the operation of existing process equipment, and provide technical guarantee for the gradual transition of process equipment to new-generation products.
The fierce competition in the market economy and the inherent strict requirements of pressure vessel products have led to an increasingly high degree of specialization in the production of pressure vessel products. As a result, standard component manufacturing and supply units have emerged, such as professional head manufacturing plants, pipe fitting manufacturing plants, heat treatment units, non-destructive testing units, etc. These independent manufacturing plants and units have made the production of pressure vessel products more efficient. The detection is more effective. Therefore, the development direction of pressure vessels must be given attention and a more efficient and intensive path should be embarked upon.
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The definition and application of pressure vessels
2025-05-09
Pressure vessels generally refer to closed containers used in industrial production to complete processes such as reactions, heat transfer, mass transfer, separation, and storage, and to withstand pressures above 0.1 MPa of gauge pressure.
The 'Regulations on Safety Supervision of Special Equipment' clearly states that the definition of pressure vessels is:
Pressure vessel
A pressure vessel refers to a closed device that holds gas or liquid and bears a certain pressure. Its scope is defined as a maximum working pressure greater than or equal to 0.1 MPa (gauge pressure). Fixed and mobile containers for gases, liquefied gases and liquids with a maximum working temperature higher than or equal to the standard boiling point, where the product of pressure and volume is greater than or equal to 2.5 MPa·L; Gas cylinders containing gases, liquefied gases and liquids with a standard boiling point equal to or lower than 60℃ that have a nominal working pressure greater than or equal to 0.2 MPa (gauge pressure) and a product of pressure and volume greater than or equal to 1.0 MPa·L; Oxygen chambers, etc.
Application of pressure vessels:
Pressure vessels were mainly used in the chemical industry in the early days, and the pressure was mostly below 10 megapascals. After the emergence of high-pressure production processes such as ammonia synthesis and high-pressure polyethylene, the pressure that pressure vessels are required to withstand has been increased to over 100 megapascals.
With the development of the chemical and petrochemical industries, the working temperature range of pressure vessels is becoming increasingly wide. The emergence of new working media also requires that pressure vessels be resistant to medium corrosion. The scale of many process facilities is getting larger and larger, and the capacity of pressure vessels is also constantly increasing accordingly. Since the 1960s, the development of nuclear power plants has put forward higher safety and technical requirements for reactor pressure vessels, which has further promoted the development of pressure vessels. For example, the development of the coal conversion industry requires high-temperature pressure vessels with a single weight of several thousand tons. The application of fast neutron proliferation reactors requires the solution of pressure vessels that can withstand high temperatures and liquid sodium corrosion. The development of Marine engineering requires external pressure vessels that can work at depths of several hundred to several thousand meters underwater.
A pressure vessel, in English: pressure vessel, refers to a closed device that holds gas or liquid and bears a certain pressure. In order to implement scientific management and safety supervision and inspection more effectively, China's 'Safety Supervision Regulations for Pressure Vessels' classifies pressure vessels into three categories based on working pressure, the hazard of the medium, and their role in production.
And different regulations have been made for each category of pressure vessels in the design, manufacturing process, as well as the inspection items, contents and methods. The safety and quality licensing system for imported goods has been implemented for pressure vessels. Goods that have not obtained the import safety and quality licensing certificate are not allowed to be imported. According to the latest TSG21-2016 'Safety Technical Supervision Regulations for Fixed Pressure Vessels', the vessels should first be classified into the first group of media and the second group of media based on the medium, and then into categories I, II, and III based on pressure and volume. The so-called first, second, and third categories in the old pressure vessel regulations are no longer applicable.
Pressure vessels are all closed containers capable of withstanding pressure. Pressure vessels have an extremely wide range of applications and play an important role in many sectors such as industry, civil use, military industry, as well as in many fields of scientific research. Among them, pressure vessels are most widely used in the chemical industry and petrochemical industry. The pressure vessels applied in the petrochemical industry alone account for about 50% of the total number of pressure vessels. Pressure vessels are mainly used in the fields of chemical engineering and petrochemicals for processes such as heat transfer, mass transfer, and reaction, as well as for storing and transporting pressurized gases or liquefied gases. It also has extensive applications in other industrial and civil fields, such as air compressors. All kinds of special compressors and auxiliary equipment of refrigeration compressors (coolers, buffers, oil-water separators, gas storage tanks, evaporators, liquid refrigerant storage tanks, etc.) all belong to pressure vessels.
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