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 cryogenic pressure vessels such as LNG tanks, oxygen-nitrogenargon tanks, CO2 tanks; pressure vessel products like denitration engineering equipment, heat storage and energy storage equipment, complete chemical equipment; and central air conditioning and HVAC 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 testing method used to inspect the tank's sealing and pressure resistance performance. Below are the general steps for the water pressure test of liquid nitrogen storage tanks:
Preparation: Ensure the tank interior is clean and that all gases and liquids have been emptied from the tank. Check that the tank's seal and safety devices are functioning properly.
Fill water: Fill the tank with water, ensuring the water level is above the low water mark. Pump or other appropriate methods can 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 (typically 30 minutes to 1 hour) and observe for any abnormal conditions such as leakage or deformation in the tank.
Pressure Relief: Gradually release pressure, drain water from the tank until the interior is completely empty.
Inspection and Evaluation: Check for leaks, deformations, or other damage on the surface and interior of the tank. Evaluate the 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 (like cold rolling, cold drawing, etc.) or heat treatment (such as solution heat treatment and cold deformation), leading to dislocations and grain boundary sliding in the crystal structure, thereby enhancing the material's strength.
Low Temperature Application Advantages: 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 effectively resists plastic deformation and fracture, improving the material's 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 cryogenic storage tanks such as liquid nitrogen, liquid oxygen, and liquid argon tanks, strain-hardened austenitic stainless steel is commonly used as structural material. These vessels must withstand high pressure and impact loads at low temperatures; strain-hardening enhances the material's strength and durability, ensuring safe operation of the containers.
It is important to note that 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, it is necessary to reasonably select and apply the strain hardening of austenitic stainless steel based on specific engineering requirements and material characteristics.

Material control for low-temperature liquid storage tanks is a crucial aspect for ensuring safety and reliability. Here 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 exhibit excellent low-temperature resistance and crack resistance, maintaining strength and toughness under low-temperature conditions.
Material Quality Control: Ensure the selected materials meet relevant standards and specifications. Conduct chemical composition analysis, mechanical property tests, and impact tests on the materials to ensure 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 storage tank material, with good welding properties and crack resistance.
Welding Process Control: Monitor welding process parameters such as current, voltage, and speed to ensure the quality and reliability of weld joints. Low heat input welding methods like pulsed welding and laser welding can minimize temperature gradients and residual stresses in the heat-affected zone.
Corrosion Protection Measures: Apply anti-corrosion treatments to the internal and external metal surfaces of storage tanks to extend their service life. Options include anti-corrosion coatings and paints to safeguard the metal structure from corrosion.
Material Performance Monitoring: Regularly monitor the performance of storage tank materials, such as mechanical property tests,

The liquid oxygen tank possesses the following characteristics:
High Purity: The liquid oxygen tanks store high purity liquid oxygen, typically achieving a purity of over 99.5%. This makes liquid oxygen tanks essential in applications requiring high purity oxygen, such as medical, industrial, and research fields.
Low Temperature: Liquid oxygen has a boiling point of -183°C, hence the liquid oxygen storage tank must have excellent insulation properties to maintain the low temperature state of the liquid oxygen. Tanks are typically designed with double or multi-layer structures, filled with insulating material in between to reduce heat transfer and the evaporation of liquid oxygen.
High Pressure: Liquid oxygen storage 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 can support combustion. Therefore, during the design and operation of liquid oxygen storage tanks, fire prevention measures must be implemented to ensure there are no ignition sources nearby, and appropriate fire extinguishing equipment is provided.
High Density: Liquid oxygen has a higher density, allowing liquid oxygen tanks to store more oxygen compared to gas oxygen. This gives liquid oxygen tanks an advantage in applications requiring large oxygen supplies, such as in the field.
Corrosiveness: Liquid oxygen has certain properties of corrosiveness.
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