Pressure Vessel

​     Pressure vessels are very important equipment in many industries.

     Usually a pressure vessel is a sealed vessel that bears gas or liquid pressure inside or outside and has high requirements for safety.

     It has an important position and role in many sectors such as industry, civilian use, military industry, and many fields of scientific research. Among them, the most used in the chemical industry and the petrochemical industry, the pressure vessels used in the petrochemical industry alone account for about 50% of the total number of pressure vessels.

     In the chemical and petrochemical industry, pressure vessels are mainly used for heat transfer, mass transfer, reaction and other processes, as well as storage and transportation of pressurized gas or liquefied gas; they are also widely used in other industrial and civil fields, such as air compressor. 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.) are all pressure vessels.

     Pressure vessels are mainly cylindrical and a few other kinds are spherical or other shapes. Cylindrical pressure vessels are usually composed of cylinders, heads, pipes, flanges and other parts and components. The higher the working pressure of the pressure vessel, the thicker the cylinder wall should be.

    The pressure vessel manufacturing process can generally be divided into: raw material acceptance process, marking process, cutting process, derusting process, machining (including edge planing, etc.) process, rolling process, assembly process, welding process (product welding test Plate), non-destructive testing process, hole marking process, general inspection process, heat treatment process, pressure test process, anti-corrosion process.

     Different welding methods have different welding processes. The welding process is mainly determined according to the material, brand, chemical composition of the welded workpiece, the structure type of the weldment, and the welding performance requirements. We must first determine the welding method, such as manual arc welding, submerged arc welding, argon tungsten arc welding, MIG welding, etc. There are many types of welding methods, which can only be selected according to specific conditions.

     After the welding method is determined, the welding process parameters are formulated. The types of welding process parameters are different. For example, manual arc welding mainly includes: electrode type (or brand), diameter, current, voltage, welding power source type, polarity connection and welding the number of layers, channels, inspection methods, etc.

There are many ways to classify pressure vessels. From the perspective of use, manufacturing and supervisory inspection, there are mainly the following.

●Classification according to pressure level: Generally, pressure vessels can be divided into internal pressure vessels and external pressure vessels.

  The internal pressure vessel can be divided into four pressure levels according to the design pressure (p), and the specific divisions are as follows

  Low pressure vessel (0.1Mpa to 1.6Mpa), Medium pressure vessel (1.6Mpa to 10Mpa),

  High pressure vessel (10Mpa to 100Mpa), Super High Pressure Vessel (≥ 100Mpa).

●According to the role and working principle of the production process

  It can be divided into:

1. Reaction pressure vessel (R): mainly used to complete the physical and chemical reaction of the medium pressure vessel. Such as reactors, reaction kettles, decomposition pots, vulcanization tanks, decomposition towers, polymerization towers, autoclaves, ultra-high pressure kettles, synthesis towers, shift furnaces, cooking pots, steaming balls, autoclaves, gas generators, etc.

2. Heat exchange pressure vessel (E): It is mainly a pressure vessel used to complete the heat exchange of the medium. Such as shell-and-tube waste heat boilers, heat exchangers, coolers, condensers, evaporators, heaters, sterilization pots, dyers, dryers, steaming pans, preheating pots, solvent preheaters, steaming pots, steaming off Generators, electric steam generators, water jackets of gas generators, etc.

3. Separation pressure vessel (S): It is mainly used to complete the fluid pressure balance buffering of the medium and the pressure vessel for gas purification and separation. Such as separators, filters, oil collectors, buffers, scrubbers, absorption towers, copper scrubbing towers, drying towers, stripping towers, sub-cylinders, deaerators, etc.

4. Storage pressure vessel (C, where the spherical tank is B): mainly used to store and hold gas, liquid, liquefied gas and other media, such as various types of storage tanks.

●Comprehensive classification

1. Fixed pressure vessel: The use environment is fixed and cannot be moved. There are many types of working media, most of which are toxic, flammable, explosive and corrosive chemical hazardous materials. Such as spherical storage tanks, horizontal storage tanks, various heat exchangers, synthesis towers, reactors, dryers, separators, shell-and-tube waste heat boilers, manned vessels (such as medical oxygen cabins), etc.

2. Movable pressure vessel: It is mainly used on the move, and is carried on a transportation tool as a packaging for a certain medium. Many working media are flammable, explosive or toxic. Such as the tank bodies of automobiles and railway tank cars.

3. Gas cylinder pressure vessel: As a kind of pressure vessel, the society has a very large amount, including high-pressure gas cylinders (such as hydrogen, oxygen, nitrogen cylinders) and low-pressure gas cylinders (such as civil liquefied petroleum gas cylinders), working medium many are also flammable, explosive or toxic substances. It also has strong mobility, both for long-distance movement during transportation and short-distance movement during specific use. Such as liquefied petroleum gas cylinders, oxygen cylinders, hydrogen cylinders, nitrogen cylinders, carbon dioxide cylinders, liquid chlorine cylinders, liquid ammonia cylinders and dissolved acetylene cylinders.

●Pressure vessel safety accessories

1. Safety valve: The function of the safety valve is to automatically open when the pressure in the equipment exceeds the specified requirements, release the excess pressure, and return the equipment to the normal working pressure state. After the pressure is normal, the safety valve closes automatically.

After the safety valve is checked, it is strictly forbidden to increase the setting pressure of the safety valve or make the safety valve invalid by means such as adding weight, moving the heavy hammer, and blocking the valve clack.

2. Pressure gauge: The range of the pressure gauge should be compatible with the working pressure of the equipment, usually 1.5 to 3 times the working pressure, preferably 2 times. A red line should be drawn on the pressure gauge dial to indicate the maximum allowable working pressure. The connecting pipe of the pressure gauge should not leak water or steam, otherwise the indication value of the pressure gauge will be reduced.

3. Rupture disc

4. Thermometer

5. Level gauge

6. Pressure reducing valve

7. Emergency cut-off device: When the pipeline and its accessories are ruptured and mis-operated, or a fire accident occurs near the tanker, the valve can be urgently closed to quickly cut off the gas source to prevent the spread of the accident.

8. Safety interlocking device for quick-opening pressure vessels: The quick-opening safety interlocking alarm device is an effective measure to prevent operation accidents of quick-opening pressure vessels. Its role is:

a. The interlocking control function of boosting operation only when the quick opening door reaches the predetermined closing position;

b. When the internal pressure of the pressure vessel is completely released and the safety interlock device is disengaged, the interlock linkage function of the quick opening door can be opened;

c. It has an alarm function synchronized with the above actions

    Typical of industry application include petrochemical industry pressure vessels, chemical pressure vessels, oil refinery pressure vessels, chemical fiber plant pressure vessels, power plant pressure vessels, hydropower station pressure vessels, marine pressure vessels, metallurgical pressure vessels, steel industry pressure vessels, city gas pressure vessels, mechanical industry pressure vessels, urban construction pressure vessels, city heating pressure vessels, marine service pressure vessels, pharmaceuticals industry pressure vessels, food industry pressure vessels, pipeline service pressure vessels, environmental protection service pressure vessels, rural and urban heating pressure vessels, rural urban building applications pressure vessels etc.

      We seafly are dedicated to provide best solution of industrial pressure vessels for our customer. All kinds of industrial pressure vessels are designed and manufactured according to user’s requirements and international standard.

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