Shandong Zhongjie Special Equipment's main products include: fuel (gas) boilers, organic heat carrier boilers, biomass boilers, waste heat boilers, and other boiler products; vacuum insulation deep-chilled pressure vessels such as LNG tanks, oxygen/nitrogen/argon tanks, and CO2 tanks; pressure vessel products such as denitrification engineering equipment, heat storage and energy storage equipment, and complete chemical equipment; central air conditioning and ventilation equipment such as ground (water) source heat pumps, air source units, water-cooled screw units, and air-cooled modular units. Planned products include large-scale energy centers, LNG transport vehicles, LNG tank containers, and other green energy equipment.
A water pressure test for liquid nitrogen storage tanks is a common method used to inspect the tank's sealing and pressure resistance. Below are the general steps for the water pressure test of liquid nitrogen storage tanks:
Preparation: Ensure the tank is clean inside and that the tank is empty of gases and liquids. Check the tank's sealing and safety devices for proper functioning.
Fill water: Fill the tank with water to ensure the water level is above the low water mark. Pump or other appropriate methods may be used for filling.
Apply Pressure: Gradually increase water pressure using a pressure pump or other pressure source until reaching the predetermined test pressure. The test pressure is typically 1.1 times the design working pressure of the tank.
Pressure Maintenance: After reaching the test pressure, maintain it for a period (usually 30 minutes to 1 hour), and observe for any abnormal conditions such as leaks or deformation in the tank.
Pressure Release: Gradually release pressure to drain water from the tank until the tank is completely empty.
Inspection and Evaluation: Check for leaks, deformation, or any other damage on the tank's surface and interior. Evaluate test results to ensure the tank meets design requirements and safety standards.
需要注意的是，液氮储罐水压试验需要由人员进行操作，并遵循相关的安全操作规程。在进行测试前，应仔细阅读和遵守储罐制造商提供的操作指南和安全注意事项。

The application of strain hardening in austenitic stainless steel on low-temperature pressure vessels is a common method, which can enhance the material's strength and durability. Here are some details regarding the application of strain-hardened austenitic stainless steel on low-temperature pressure vessels:
Principle of Strain Hardening: Strain hardening is achieved by introducing plastic deformation into the material, which alters the crystal structure and thereby increases the material's strength. In Austenitic stainless steel, strain can be introduced through methods such as cold working (e.g., cold rolling, cold drawing) or heat treatment (e.g., solution treatment and cold deformation), leading to dislocation and grain boundary slip in the crystal structure, thereby enhancing the material's strength.
Advantages of Low-Temperature Applications: Austenitic stainless steel exhibits excellent corrosion resistance and low-temperature toughness in cold environments. Strain hardening can further enhance the strength and durability of austenitic stainless steel, enabling it to perform in low-temperature pressure vessels. Under low-temperature conditions, strain hardening can effectively resist plastic deformation and fracture of the material, improving its tensile strength and impact resistance.
Application Cases: The strain-hardening of austenitic stainless steel is widely used in low-temperature pressure vessels. For instance, in low-temperature containers such as liquid nitrogen, liquid oxygen, and liquid argon tanks, strain-hardened austenitic stainless steel is commonly employed as structural material. These containers must withstand high pressures and impact loads at low temperatures; strain-hardening enhances the material's strength and durability, ensuring safe operation of the vessels.
It is important to note that the strain hardening of austenitic stainless steel should be carried out at appropriate temperatures and deformation conditions to avoid excessive deformation and material embrittlement. When designing and manufacturing low-temperature pressure vessels, the specific engineering requirements and material characteristics should be considered to rationally select and apply the strain hardening of austenitic stainless steel.

Material control for low-temperature liquid storage tanks is a crucial aspect in ensuring their safety and reliability. The following are some common material control measures:
Material Selection: Choose materials suitable for low-temperature environments, such as low-temperature alloy steel, stainless steel, etc. These materials offer excellent low-temperature resistance and crack resistance, maintaining strength and toughness under low-temperature conditions.
Material Quality Control: Ensure that the selected materials meet relevant standards and specifications. Conduct chemical composition analysis, mechanical property tests, and impact tests on materials to confirm that their performance meets design requirements.
Welding Material Selection: Choose welding materials suitable for low-temperature environments, such as low-temperature welding rods or welding wires. The welding materials should match the tank material, offering excellent welding properties and crack resistance.
Welding Process Control: Monitor and control welding process parameters such as current, voltage, and welding speed to ensure the quality and reliability of焊接 joints. Utilize low heat input welding methods like pulse welding and laser welding to minimize temperature gradients and residual stresses in the heat-affected zone.
Corrosion Prevention Measures: Apply corrosion-resistant treatments to the internal and external metal surfaces of the storage tank to extend its service life. Options include corrosion-resistant coatings and paints to protect the metal structure of the tank from corrosion.
Material Performance Monitoring: Regularly conduct performance monitoring of the storage tank materials, such as mechanical property tests,

Liquid oxygen tanks possess the following characteristics:
High Purity: The liquid oxygen storage tank contains liquid oxygen of high purity, typically exceeding 99.5%. This makes the liquid oxygen tank essential in applications requiring high-purity oxygen, such as medical, aerospace, and research fields.
Low Temperature: As the boiling point of liquid oxygen is -183°C, liquid oxygen storage tanks must have excellent thermal insulation properties to maintain the low temperature of the liquid oxygen. Tanks are typically designed with double or multi-layer structures, filled with insulating material in between to minimize heat transfer and evaporation of the liquid oxygen.
High Pressure: Liquid oxygen tanks typically need to withstand high pressure to maintain their liquid state. The design and material selection of the tank must consider the pressure requirements of liquid oxygen to ensure the tank's safety and reliability.
Flammability: Liquid oxygen is highly flammable and supports combustion. Therefore, during the design and use of liquid oxygen storage tanks, fire prevention measures must be implemented to ensure there are no ignition sources around the tank, and appropriate fire extinguishing equipment is provided.
High Density: With a higher density than gaseous oxygen, liquid oxygen tanks can store more oxygen. This gives liquid oxygen tanks an advantage in applications requiring large oxygen supplies, such as in the field.
Corrosiveness: Liquid oxygen has certain腐蚀性 properties.
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